Questions aléatoires SYLC Flashcards

Question 1

Q

The “hook effect” is a type of interference that primarily affects the following types of immunoassays?

A. nephelometric/turbidometric

B. competitive & immunometric

C. competitive & homogeneous

D. homogenous & heterogenous

Answer

A

Correct answer A.

The hook effect is decreased apparent analyte concentration at very high concentrations because of the antigen excess saturating antibody binding sites, is seen primarily in nephelometric, turbidometric, and immunometric assays. However in immunometric assays, the hook effect only occurs if there is no wash step before adding the second antibody.

Hook effect affects sandwich assays by saturating the capture antibody sites and label antibody sites preventing a sandwich formation from occurring if done in only one step. Knowing this rules out B and C as competitive assays should not be affected. A heterogenous assays having a washing step also prevents saturation of the labeling antibody which is added later after excess analyte is removed.

Question 2

Q

An important renal response to acidemia is . . .

A - increased potassium excretion.

B - increased production of ammonia.

C - decreased excretion of H2PO−4.

D - increased production of HPO42−.

Answer

A

The answer is B increased production of ammonia

The kidney cannot excrete significant quantities of free hydrogen ion. The most important renal response to academia is to increase the production of ammonia from glutamine. Ammonia combines with H+ in the renal tubule, and NH4− is excreted.

Question 3

Q

α-Thalassemia minor includes which of the following characteristic laboratory findings?

A. microcytosis, increased red cell number, normal red cell distribution width (RDW), and increased ferritin levels

B. microcytosis, normal red cell number, normal RDW, and decreased ferritin levels

C. microcytosis, decreased red cell number, normal RDW and increased ferritin levels

D. microcytosis, increased red cell number, elevated RDW and increased ferritin levels

E. microcytosis, decreased red cell number, elevated RDW and decreased ferritin levels

Answer

A

Answer : A

Question 4

Q

What is the osmolal gap, given the following data?
Freezing point depression = −0.6324 °C
Glucose = 95 mg/dL
Na = 138 mmol/L
Urea nitrogen = 28 mg/dL

A. 9 mOsm
B. 19 mOsm
C. 29 mOsm
D. 39 mOsm
E. 49 mOsm

Answer

A

E

One osmole of solute decreases the freezing point by 0.00186 degrees Celsius; therefore 0.6324/0.00186 = 340 mOsm/kg (measured). Calculated osmolality = (2Na) + (glucose/18) + (urea nitrogen/2.8); which comes out to 291 mOsm/Kg. Gap therefore equals 49 mOsm.

Question 5

Q

A patient seen in the clinic has a blood specimen drawn for cholesterol analysis; the results are cholesterol = 225 mg/dL, high-density lipoproteins (HDL) = 74 mg/dL, and triglycerides = 188 mg/dL. What is the indirect LDL value for this patient?

A - 37 mg/dL

B - 151 mg/dL

C - 187 mg/dL

D - 70 mg/dL

E - 113 mg/dL

Answer

A

Correct answer is 113 mg/dL.

Friedewald equation: LDL = total cholesterol − HDL − (triglycerides/5)

LDL = 225 mg/dL − 74 mg/dL − (188/5) mg/dL

= 113 mg/dL

Question 6

Q

Which of the following is the best method to use for determining whether a positive opiate urine drug screen is a result of poppy seed consumption?

A. testing for morphine by GC/MS in the same sample

B. testing for diacetylmorphine by GC/MS in the same sample

C. testing for monoacetyl morphine by GC/MS in the same sample

D. having patients discontinue ingesting poppy seed products and observe opiate EIAs reverting to negative levels in 48 h

E. testing for poppy seed byproducts in the urine

Answer

A

Answer: C

Poppy seeds contain morphine and codeine; therefore, patients consuming poppy seeds and heroin will test positive for opiates in general and specifically for morphine. However, only patients abusing heroin will test positive for 6-monoacetylmorphine, since it can only be produced from heroin.

Question 7

Q

Which of the following may raise the set point in the parathyroid gland for negative feedback, eliciting hypercalcemia?

A. Vitamin D deficiency
B. Hypomagnesemia
C. Chronic lithium therapy
D. Acute pancreatitis
E. Renal Disease

Answer

A

C. Chronic lithium therapy

Question 8

Q

A 38-year-old male with chronic back pain is prescribed 10-mg oxycodone tablets up to seven times per day. The results of a urine opioid confirmatory test showed codeine (973 ng/mL), hydrocodone (582 ng/mL), hydromorphone (94 ng/mL), and morphine (1300 ng/mL). The results from this test indicate that the patient is most likely taking which of the following?

A. oxycodone and codeine

B. morphine only

C. morphine and hydrocodone

D. codeine and morphine

E. codeine, hydrocodone, and morphine

Answer

A

E. codeine, hydrocodone, and morphine

Question 9

Q

Identify the correct statement regarding the use of population-based reference intervals based on the central 95% of the reference distribution.

A. Population-based reference intervals result in more false negatives than decision levels based on outcomes.
B. Population-based reference intervals result in more false positives than decision levels based on outcomes.
C. Population-based reference intervals are more sensitive than subject-based reference intervals.
D. Approximately 20% of comprehensive metabolic panels (14 tests) will have one or more abnormal results when performed on healthy individuals.
E. The probability of normal result(s) = (0.95)N , where N = number of tests performed.

Answer

A

E. The probability of normal result(s) = (0.95)N , where N = number of tests performed.

Question 10

Q

Using the bicarbonate-carbonic acid buffer system, if the apparent pKa value is 6.1 and the ratio of bicarbonate to carbonic acid is 10:1, what is the pH of the solution?

6.1
7.1
7.4
7.5
7.7

Answer

A

Correct answer : 7.1

Henderson-Hasselbalch equation:

pH = pKa + log ([A−]/[HA])

pKa = 6.1; [A−]/[HA] = 10

pH = 6.1 + log 10 = 7.1

Question 11

Q

Elevated NT-proBNP levels in pleural fluid are seen in which of the following?

A. tuberculous effusions

B. transudative effusions due to heart failure

C. transudative effusions due to liver cirrhosis

D. rheumatoid arthritis

E. empyema

Answer

A

B. transudative effusions due to heart failure

Question 12

Q

LDL-cholesterol can be measured directly by first removing non-LDL lipoproteins (i.e., VLDL, IDL, and HDL). The direct measurement makes use of antibodies specific to two apoproteins on non-LDL lipoproteins. What is one apoprotein that would likely be targeted by the antibody?

A. apo B-100
B. apo C-II
C. apo E
D. apo B-48
E. apo (a)

Answer

A

E. apo (a)

Question 13

Q

Which of the following vitamins would be LEAST affected by long periods of fat malabsorption?

vitamin A
vitamin C
vitamin D
vitamin E
vitamin K

Answer

A

Correct answer: Vitamin C

Vitamins A, D, E, K are all fat soluble.

Question 14

Q

How does multiple myeloma (MM) differ from Waldenström macroglobulinemia (WM)?

A. fewer lytic lesions and less bone pain with MM

B. lower incidence of serum hyperviscosity in MM

C. fewer recurrent bacterial infections with MM

D. higher incidence of monoclonal IgM in MM

E. more visual disturbances occur with MM

Answer

A

How does multiple myeloma (MM) differ from Waldenström macroglobulinemia (WM)?

A. fewer lytic lesions and less bone pain with MM

B. lower incidence of serum hyperviscosity in MM

C. fewer recurrent bacterial infections with MM

D. higher incidence of monoclonal IgM in MM

E. more visual disturbances occur with MM

Question 15

Q

Wilson’s disease is a genetic disorder characterized by hepatocellular damage and/or a change in mood and behavior caused by the accumulation of which metal?

a) copper
b) iron
c) chromium
d) cobalt
e) selenium

Answer

A

Wilson’s disease is a genetic disorder characterized by hepatocellular damage and/or a change in mood and behavior caused by the accumulation of which metal?

*a) copper**
b) iron
c) chromium
d) cobalt
e) selenium

The presentation of copper (Cu) toxicosis is represented by Wilson’s disease. Serum and urine copper concentrations can be useful in diagnosing Wilson’s disease. The majority of Cu circulating in blood is bound to ceruloplasmin. However, ceruloplasmin expression is decreased in Wilson’s disease. As a result, serum Cu concentrations are less than the reference interval (0.7–1.4 μg/mL), while urinary concentrations are increased to 15–60 μg/mL in patients with Wilson’s disease.

Question 16

Q

Maple syrup urine disease (MSUD) is characterized by sweet smelling urine, which is caused by which of the following?

branched-chain amino acids excreted in urine
glucosuria
phenylketonuria
no one knows
elevated, isolated urinary excretion of alloisoleucine

Answer

A

Maple syrup urine disease (MSUD) is characterized by sweet smelling urine, which is caused by which of the following?

branched-chain amino acids excreted in urine
glucosuria
phenylketonuria
no one knows
elevated, isolated urinary excretion of alloisoleucine

MUSD is a genetic disorder results in a defect in the enzyme responsible in de-branching/digesting certain amino acids. The accumulation of these amino acids and there excretion into urine gives the urine a sweet smell.

Question 17

Q

An increase in the affinity of hemoglobin for O2 can be caused by which of the following?

A. Decrease in H+ concentration
B. Increase in temperature
C. Increase in CO2 pressure
D. Increase in 2,3-diphosphoglycerate concentration
E. Decrease in Na+ concentration

Answer

A

An increase in the affinity of hemoglobin for O2 can be caused by which of the following?

A. Decrease in H+ concentration
B. Increase in temperature
C. Increase in CO2 pressure
D. Increase in 2,3-diphosphoglycerate concentration
E. Decrease in Na+ concentration

Question 18

Q

An 18 yo female presents to the emergency department with nausea, vomiting, fatigue, decreased appetite and a 20-lb weight loss. Blood is drawn for analysis, and her results reveal low sodium (115 mmol/L) and cortisol (188 nmol/L) and very high ACTH (912 ng/L). Additional cortisol testing was performed following a 1-h cosyntropin stimulation test with 250 μg, and cortisol remained low.

Which one of the following conditions is most likely present in this patient?

A. Cushing disease

B. Cushing syndrome

C. primary adrenal insufficiency (Addison’s disease)

D. secondary adrenal insufficiency

E. ACTH-secreting tumor

Answer

A

A. Cushing disease –> this is incorrect because patients typically gain weight, have high cortisol

B. Cushing syndrome –> similar to above; only the source of excess ACTH is ectopic, rather than pituitary and we would observe an increase in circulating cortisol

C. Addison’s disease –> fatigue, weakness, hyponatremia, vomiting, weight loss are typical presentation. ACTH stimulation does not induce increase in cortisol.

D. Secondary adrenal insufficiency–> incorrect, because low ACTH would be observed

E. ACTH-secreting tumor–> see A and B

Question 19

Q

A 23-y-old female presents to the emergency department with an intrauterine pregnancy at 27 weeks 3 days gestation. The patient complains of abdominal pain, contractions, and mild vaginal spotting for the past 24 h. The patient has a history of chlamydia (3 months ago) and three previous preterm deliveries. Cervicovaginal fetal fibronectin (fFN) testing was negative. How should this patient be treated?

A. Give the patient antenatal corticosteroids to induce fetal lung maturity.
B. Admit the patient and treat with a tocolytic agent, like terbutaline.
C. Discharge the patient with recommendation of pelvic rest and follow up in 1 to 2 weeks.
D. Induce delivery immediately.
E. fFN testing is inaccurate in the presence of a chlamydia infection.

Answer

A

The correct answer is C. The strength of fFN is its high negative predictive value, >99% for predicting birth within 7 days of sampling. Therefore, a symptomatic patient with a negative fFN result has <1% chance of delivering within the next week and can be sent home.

Question 20

Q

A lecithin-sphingomyelin (L/S) ratio is typically performed to diagnose which of the following?

a. bacterial meningitis
b. viral meningitis
c. cystic fibrosis
d. fetal lung maturity
e. multiple sclerosis

Answer

A

A lecithin-sphingomyelin (L/S) ratio is typically performed to diagnose which of the following?

a. bacterial meningitis
b. viral meningitis
c. cystic fibrosis

d. fetal lung maturity (très rare maintenant comme test)

e. multiple sclerosis

Question 21

Q

A blood specimen from a normal control is drawn into a citrated tube and is mixed in vitro with powdered Coumadin (warfarin). Which of the following effects would one expect to see?

A. Prolonged PT
B. Prolonged aPTT
C. Prolonged thrombin time (TT)
D. False-positive heparin assay
E. No effect

Answer

A

A blood specimen from a normal control is drawn into a citrated tube and is mixed in vitro with powdered Coumadin (warfarin). Which of the following effects would one expect to see?

A. Prolonged PT
B. Prolonged aPTT
C. Prolonged thrombin time (TT)
D. False-positive heparin assay
E. No effect

Coumadin or warfarin has no effect in vitro. Its action is on the vitamin K-dependent posttranslational modification of clotting factors by the liver. On the other hand, heparin will prolong the PTT and TT in vitro, and at very high doses, the PT will prolong as well.

Question 22

Q

Which of the following tube types should be specifically avoided when performing PCR-based tests?

A. EDTA

B. sodium citrate

C. lithium heparin

D. serum separator

Answer

A

Which of the following tube types should be specifically avoided when performing PCR-based tests?

A. EDTA

B. sodium citrate

C. lithium heparin

D. serum separator

Heparin inhibits Taq polymerase, it is a general DNA binding protein. Sodium heparin has also been known to inhibit DNA polymerase activity in PCR assays.

Question 23

Q

Which measurement is consistent with anovulation?

High FSH on cycle day 3
Low progesterone on cycle day 21
High LH on cycle day 14
Low estradiol on cycle day 3
Low LH on cycle day 21

Answer

A

Which measurement is consistent with anovulation?

High FSH on cycle day 3
Low progesterone on cycle day 21
High LH on cycle day 14
Low estradiol on cycle day 3
Low LH on cycle day 21

Following ovulation, which occurs on or near cycle day 14, the ruptured follicle gives rise to the corpus luteum, which produces estrogen and progesterone. Low concentrations of progesterone during the luteal phase indicate that ovulation has not occurred.

Question 24

Q

Which of the following quality control (QC) options best describes the traditional approach to satisfying the CLIA QC requirement?

A. assaying one level of QC twice per day

B. assaying two levels of QC once per day

C. assaying two levels of QC twice per day

D. assaying three levels of QC once per day

E. assaying three levels of QC twice per day

Answer

A

Which of the following quality control (QC) options best describes the traditional approach to satisfying the CLIA QC requirement?

A. assaying one level of QC twice per day

B. assaying two levels of QC once per day

C. assaying two levels of QC twice per day

D. assaying three levels of QC once per day

E. assaying three levels of QC twice per day

At a minimum, for quantitative testing, laboratories must analyze two levels of QC at different concentrations once each day of patient testing.

Question 25

Q

A reference interval (RI) study was performed as part of a method validation for a new total protein assay. The distribution is Gaussian, with a mean of 7.2 g/dL, and a standard deviation (SD) of 0.36 g/dL. The RI for this assay should be listed as which of the following?

a) 6.8 – 7.6 g/dL
b) 6.5 – 7.9 g/dL
c) 6.1 – 8.3 g/dL
d) 5.8 – 8.6 g/dL

Answer

A

A reference interval (RI) study was performed as part of a method validation for a new total protein assay. The distribution is Gaussian, with a mean of 7.2 g/dL, and a standard deviation (SD) of 0.36 g/dL. The RI for this assay should be listed as which of the following?

a) 6.8 – 7.6 g/dL
* *b) 6.5 – 7.9 g/dL**
c) 6.1 – 8.3 g/dL
d) 5.8 – 8.6 g/dL

Reference intervals (RI) are established by analyzing at least 120 samples from “healthy” patients within each of the appropriate reference populations. If the data is normally distributed (Gaussian), a parametric method can be used to determine the RI with the following calculations:
Lower end of RI = mean – (1.96 × SD)
Upper end of RI = mean + (1.96 × SD)

Question 26

Q

Pyruvate kinase deficiency is associated with which of the following features?

A. autosomal recessive inheritance pattern and congenital nonspherocytic hemolytic anemia
B. autosomal dominant inheritance pattern and congenital nonspherocytic hemolytic anemia
C. X-linked inheritance pattern and hereditary bone marrow failure
D. autosomal recessive inheritance pattern and progressive bone marrow failure
E. autosomal dominant inheritance pattern and hereditary bone marrow failure

Answer

A

Pyruvate kinase deficiency is associated with which of the following features?

A. autosomal recessive inheritance pattern and congenital nonspherocytic hemolytic anemia
B. autosomal dominant inheritance pattern and congenital nonspherocytic hemolytic anemia
C. X-linked inheritance pattern and hereditary bone marrow failure
D. autosomal recessive inheritance pattern and progressive bone marrow failure
E. autosomal dominant inheritance pattern and hereditary bone marrow failure

Pyruvate kinase deficiency is one of the most common glycolytic pathway deficiencies that results in anemia due to hemolysis. Hemolysis is secondary to insufficient ability of the glycolytic pathway to produce ATP for red cell metabolic needs and is evident at birth, manifesting as a normochromic, normocytic anemia. Formation of spherocytes is not characteristic of pyruvate kinase deficiency, leading to designation as a congenital nonspherocytic hemolytic anemia. As with most glycolytic pathway enzymatic deficiencies, pyruvate kinase deficiency arises as mutation in the enzyme that is inherited as an autosomal recessive trait.

Question 27

Q

A 3-y-old boy with a right abdominal mass has elevated homovanillic acid (HVA) and vanillylmandelic acid (VMA) detected in his urine. Which of the following is the most probable diagnosis?

A. neuroblastoma

B. Wilms tumor

C. congenital polycystic renal disease

D. pheochromocytoma

E. hepatoma

Answer

A

A 3-y-old boy with a right abdominal mass has elevated homovanillic acid (HVA) and vanillylmandelic acid (VMA) detected in his urine. Which of the following is the most probable diagnosis?

A. neuroblastoma

B. Wilms tumor

C. congenital polycystic renal disease

D. pheochromocytoma

E. hepatoma

HVA and VMA are end products resulted from breakdown of the catecholamines; dopamine (to HVA) and epinephrine (to VMA). Elevated HVA and VMA is suggestive of Pheochromocytoma but supports the diagnosis of Neuroblastoma (beacause of the age of the patient).

Neuroblastoma usually it presents with abdominal mass and VMA and HVA are elevated in urine because neuroblastoma cells make catecholamines and their products amount in blood and urine are higher than normal.

Pheochromocytoma : although HVA and VMA can be elevated, but an abdominal mass is not usually present and most of the times this tumor is discovered later after 20 years of age. Metanephrines measurement is more sensitive diagnosis in this disease.

Question 28

Q

Which of the following specimen types has the highest likelihood for detecting arsenic (As) five days after an acute exposure?

Hair
Nails
Serum
Urine
Whole blood

Answer

A

Which of the following specimen types has the highest likelihood for detecting arsenic (As) five days after an acute exposure?

Hair
Nails
Serum
Urine
Whole blood

The half-life of inorganic Arsenic in blood is approximately 4–6 hours, while methylated metabolites have a half-life of 20–30 hours. Therefore, blood concentrations of Arsenic will only be elevated for a short time after exposure. Although hair or nail analysis is frequently used, it is best suited for cases of suspected chronic exposure. Urine is the sample of choice for Arsenic analysis due to its concentration and excretion by the kidneys.

Question 29

Q

Which plasma profile is consistent with primary hyperparathyroidism?

high PTH, high calcium, low phosphate
high PTH, low calcium, high phosphate
low PTH, high calcium, low phosphate
low PTH, low calcium, low phosphate

Answer

A

Which plasma profile is consistent with primary hyperparathyroidism?

high PTH, high calcium, low phosphate
high PTH, low calcium, high phosphate
low PTH, high calcium, low phosphate
low PTH, low calcium, low phosphate

Parathyroid hormone (PTH) acts directly on bone stores and the kidneys to increase plasma calcium concentrations. PTH also promotes renal excretion of phosphate lowering plasma phosphate concentrations.

Question 30

Q

Which is the most appropriate test to assess a patient in which pheochromocytoma is suspected?

a. urine 5-HIAA
b. plasma catecholamines
c. plasma serotonin
d. urine norepinephrine
e. plasma metanephrines

Answer

A

Which is the most appropriate test to assess a patient in which pheochromocytoma is suspected?

a. urine 5-HIAA
b. plasma catecholamines
c. plasma serotonin
d. urine norepinephrine

e. plasma metanephrines

Plasma catecholamine release is episodic, while metabolic conversion of catecholamines to metanephrines is continuous, which makes measurement of plasma metanephrines more sensitive than plasma catecholamines. Elevations in 5-HIAA and serotonin are most commonly associated with carcinoids.

Question 31

Q

Individuals who have two mutations, one each in two different genes, that are causative of a single genetic disease are said to be which of the following?

A. Homozygous
B. Compound heterozygous
C. Hemizygous
D. Double heterozygous
E. Triple heterozygous

Answer

A

Individuals who have two mutations, one each in two different genes, that are causative of a single genetic disease are said to be which of the following?

A. Homozygous
B. Compound heterozygous
C. Hemizygous
D. Double heterozygous
E. Triple heterozygous

Double heterozygous refers to someone who is heterozygous for mutations in two genes associated with the same disease (e.g., BRCA1 and BRCA2 mutations). A compound heterozygote would be someone who has two different mutations in the same gene.

Question 32

Q

A 49-year-old male presents to the clinic with complaints of chest discomfort. Troponins and a comprehensive metabolic panel are normal except for an isolated increase in aspartate aminotransferase (AST) at 342 U/L. The result is confirmed by a second draw a week later. The patient has a history of moderate alcohol consumption with no signs of liver damage. Additional testing is normal for hepatitis A and C antibodies, albumin, bilirubin, alanine aminotransferase (ALT), alkaline phosphatase (ALP), γ-glutamyltransferase (GGT), prothrombin time (PT), activated partial thromboplastin time (APTT), lactate dehydrogenase (LDH), ferritin, hemoglobin, creatinine, ceruloplasmin, α1-antitrypsin, and creatine kinase.

Which one of the following is most likely the cause of this patient’s increased AST?

Toxic drug-induced hepatitis
Macro-AST
Alcoholic hepatitis
Wilson’s disease
Myocardial infarction

Answer

A

Which one of the following is most likely the cause of this patient’s increased AST?

Toxic drug-induced hepatitis
Macro-AST
Alcoholic hepatitis
Wilson’s disease
Myocardial infarction

Question 33

Q

Diluting urine is a simple way to make an otherwise positive drug test result negative. An attempt to escape detection by dilution may be evaluated by measuring which of the following?

total protein
glucose
bilirubin
specific gravity

Answer

A

Diluting urine is a simple way to make an otherwise positive drug test result negative. An attempt to escape detection by dilution may be evaluated by measuring which of the following?

total protein
glucose
bilirubin
specific gravity

Measurement of urinary temperature, pH, specific gravity, and creatinine may assist in determining if a urine sample has been intentionally diluted or otherwise adulterated.

Question 34

Q

The possible causes of an inappropriate increase in a glycated hemoglobin level include which of the following?

hemolytic anemia
ribavirin therapy
iron deficiency anemia
Hb S by POCT devices

Answer

A

The possible causes of an inappropriate increase in a glycated hemoglobin level include which of the following?

hemolytic anemia
ribavirin therapy
iron deficiency anemia
Hb S by POCT devices

Question 35

Q

A baby with biliary atresia is most likely to have markedly elevated serum level of:

conjugated bilirubin
unconjugated bilirubin
delta bilirubin
urine urobilinogen

Answer

A

A baby with biliary atresia is most likely to have markedly elevated serum level of:

conjugated bilirubin
unconjugated bilirubin
delta bilirubin
urine urobilinogen

Question 36

Q

Which of the following would be the most likely cause of an effusion in patients with congestive heart failure?

increased oncotic pressure
decreased oncotic pressure
increased hydrostatic pressure
decreased hydrostatic pressure

Answer

A

Which of the following would be the most likely cause of an effusion in patients with congestive heart failure?

increased oncotic pressure
decreased oncotic pressure
increased hydrostatic pressure
decreased hydrostatic pressure

Patients with congestive heart failure commonly have increased hydrostatic pressure which can lead to accumulation of fluids in serous cavities, such as the pleural cavity, and formation of an effusion.

Question 37

Q

Which of the following drugs is drawn at both peak and trough in therapeutic drug monitoring (TDM)?

Lamotrigine
Penicillin
Tobramycin
Amiodarone
Zonisamide

Answer

A

Which of the following drugs is drawn at both peak and trough in therapeutic drug monitoring (TDM)?

Lamotrigine
Penicillin
Tobramycin
Amiodarone
Zonisamide

The majority of drugs included in TDM programs are measured at trough (immediately before the next scheduled dose). However, one exception to this is aminoglycosides, like tobramycin. In order to ensure optimal efficacy, peak (Cmax) aminoglycoside concentrations should be maintained significantly above the minimum inhibitory concentration (MIC). However, trough concentrations must fall considerably before the next dose to avoid toxicity. Therefore, aminoglycoside TDM samples are drawn at peak (usually 1 hour post-dose) and at trough to monitor both therapeutic efficacy and the potential for toxicity, respectively.

Question 38

Q

What drug of abuse causes euphoria and a pronounced stimulatory effect on the CV system by inhibiting the enzyme monoamine oxidase (MAO)?

A. Opiates
B. Ethanol
C. BZs
D. Amphetamines

Answer

A

What drug of abuse causes euphoria and a pronounced stimulatory effect on the CV system by inhibiting the enzyme monoamine oxidase (MAO)?

A. Opiates
B. Ethanol
C. BZs
D. Amphetamines

Question 39

Q

Which of the following variables is not part of the MDRD equation for estimated GFR?

A. serum creatinine
B. age
C. gender
D. serum cystatin C

Answer

A

Which of the following variables is not part of the MDRD equation for estimated GFR?

A. serum creatinine
B. age
C. gender
D. serum cystatin C

Question 40

Q

Patients with porphyria cutanea tarda (PCT) have a deficiency of which of the following enzymes?

coproporphyrinogen oxidase
uroporphyrinogen decarboxylase
protoporphyrinogen oxidase
uroporphyrinogen I synthase

Answer

A

Patients with porphyria cutanea tarda (PCT) have a deficiency of which of the following enzymes?

coproporphyrinogen oxidase
uroporphyrinogen decarboxylase
protoporphyrinogen oxidase
uroporphyrinogen I synthase

PCT is an acquired or familial disorder in which uroporphyrinogen decarboxylase activity is deficient resulting in an accumulation of uroporphyrinogen, heptacarboxyl porphyrinogen, hexacarboxyl porphyrinogen, and pentacarboxyl porphyrinogen.

Question 41

Q

Neonates generally have 60–70% hematocrit. How does this impact blood collection for clinical testing?

It increases the volume of serum or plasma available from a specified volume of blood.
It decreases the volume of serum or plasma available from a specified volume of blood.
It reduces the necessary ratio of blood to anticoagulant.
It increases the necessary ratio of blood to anticoagulant.
It reduces serum or plasma stability at room temperature.

Answer

A

Neonates generally have 60–70% hematocrit. How does this impact blood collection for clinical testing?

It increases the volume of serum or plasma available from a specified volume of blood.
It decreases the volume of serum or plasma available from a specified volume of blood.
It reduces the necessary ratio of blood to anticoagulant.
It increases the necessary ratio of blood to anticoagulant.
It reduces serum or plasma stability at room temperature.

Hematocrit is the ratio of the volume of erythrocytes to whole blood. Neonates have relatively high hematocrit at 60–70%, therefore, when centrifuged, there is less volume of serum or plasma available in a given volume of blood.

Question 42

Q

When utilizing statistical quality control (QC) and Westgard multirules, which of the following best describes a 12s QC rule?

A single result outside the mean ± 2 standard deviations (SD) range
Two results on two different levels of QC outside the mean ± 1 standard deviation (SD) range
A single result exceeding the mean + 1 standard deviation (SD) followed by a consecutive result exceeding the mean − 1 standard deviation (SD)
Two consecutive results for the same level of QC outside the mean ± 1 standard deviation (SD) range
Two consecutive results for the same level of QC on the same side of the mean

Answer

A

When utilizing statistical quality control (QC) and Westgard multirules, which of the following best describes a 12s QC rule?

A single result outside the mean ± 2 standard deviations (SD) range
Two results on two different levels of QC outside the mean ± 1 standard deviation (SD) range
A single result exceeding the mean + 1 standard deviation (SD) followed by a consecutive result exceeding the mean − 1 standard deviation (SD)
Two consecutive results for the same level of QC outside the mean ± 1 standard deviation (SD) range
Two consecutive results for the same level of QC on the same side of the mean

The 1_2s QC rule refers to a single QC data point that exceeds the 2 standard deviation limits surrounding the mean QC value.

Question 43

Q

A 36 y/o woman presents to the ED complaining of anxiety, sweating, palpitations, and weight loss. Physical examination reveals enlargement of her thyroid. Lab results are TSH=0.3 mU/L, TT3=324 ng/dL, and FT4=3.3 ng/dL. Which of the following is most likely?

Hashimoto’s thyroiditis
Grave’s disease
non-thyroidal illness
thyroid hormone resistance

Answer

A

A 36 y/o woman presents to the ED complaining of anxiety, sweating, palpitations, and weight loss. Physical examination reveals enlargement of her thyroid. Lab results are TSH=0.3 mU/L, TT3=324 ng/dL, and FT4=3.3 ng/dL. Which of the following is most likely?

Hashimoto’s thyroiditis
Grave’s disease
non-thyroidal illness
thyroid hormone resistance

Question 44

Q

In electrospray ionization (ESI), which of the following is true?

A. Compounds are bombarded with a spray of electrons, which causes formation of a radical cation.
B. Compounds are vaporized by a spray of electrons, and these gas-state compounds rearrange to form charged ions.
C. Compounds are charged in solution by a high-voltage source, followed by desolvation to form ions in a gas state.
D. Compounds are ionized by a high-energy laser source and then electronically focused as a narrow “ion spray” into collection cones.
E. Compounds are ionized in solution by coaxially generated electrons and then electronically focused as a narrow ion spray into collection cones.

Answer

A

In electrospray ionization (ESI), which of the following is true?

A. Compounds are bombarded with a spray of electrons, which causes formation of a radical cation.
B. Compounds are vaporized by a spray of electrons, and these gas-state compounds rearrange to form charged ions.
C. Compounds are charged in solution by a high-voltage source, followed by desolvation to form ions in a gas state.
D. Compounds are ionized by a high-energy laser source and then electronically focused as a narrow “ion spray” into collection cones.
E. Compounds are ionized in solution by coaxially generated electrons and then electronically focused as a narrow ion spray into collection cones.

Question 45

Q

Of the given choices, which is the most common cause of chronic pancreatitis?

recurrent bouts of idiopathic acute pancreatitis
chronic alcohol abuse
autoimmune-mediated destruction of islets
chronic insulin resistance
overproduction of gastric paracrine factors

Answer

A

Of the given choices, which is the most common cause of chronic pancreatitis?

recurrent bouts of idiopathic acute pancreatitis
chronic alcohol abuse
autoimmune-mediated destruction of islets
chronic insulin resistance
overproduction of gastric paracrine factors

Question 46

Q

Which of the following transporters is responsible for exporting iron out of the enterocyte to circulation?

A. DMT-1: the divalent metal transporter
B. Ferroportin
C. Ferritin
D. Transferrin
E. Heme

Answer

A

Which of the following transporters is responsible for exporting iron out of the enterocyte to circulation?

A. DMT-1: the divalent metal transporter
B. Ferroportin
C. Ferritin
D. Transferrin
E. Heme

Ferroportin is a basolateral membrane iron transporter, also called “iron regulated transporter 1” (Ireg1) or “metal transporter protein 1” (MTP1). The gene family is termed SLC40. Ferroportin exports absorbed iron from the enterocyte to the circulation. On the other hand, DMT1 (divalent metal-ion transporter-1) is on the brush-border of the enterocyte, and it is responsible for iron entry from the GI lumen. It is also known as NRAMP2.

Question 47

Q

Of the following colorimetric methods for creatinine determination, which reagent is used in the Jaffe reaction:

A. Alkaline 3,5-dinitrobenzoic acid
B. Potassium 1,4-napthoquinone-2-sulfonate
C. Alkaline picrate
D. Alkaline acetylsalicylate
E. Diazotize sulfanilic acid

Answer

A

Of the following colorimetric methods for creatinine determination, which reagent is used in the Jaffe reaction:

A. Alkaline 3,5-dinitrobenzoic acid
B. Potassium 1,4-napthoquinone-2-sulfonate
C. Alkaline picrate
D. Alkaline acetylsalicylate
E. Diazotize sulfanilic acid

Question 48

Q

A 78-year-old female with renal disease is prescribed several new drugs. Which of the following might benefit from therapeutic drug monitoring of its free form?

vancomycin
theophylline
methotrexate
primidone
phenytoin

Answer

A

A 78-year-old female with renal disease is prescribed several new drugs. Which of the following might benefit from therapeutic drug monitoring of its free form?

vancomycin
theophylline
methotrexate
primidone
phenytoin

In order to exert its pharmacological activity, a therapeutic drug must be in its free form. However, several drugs are highly protein-bound. Patients with variable protein concentrations (pregnant, liver or kidney disease, elderly) may require therapeutic drug monitoring specifically for the free fraction of the drug. Even a small change in the proportion of protein-bound drug (for example 95% to 80%) would result in a dramatic elevation in the amount of active drug, without a change in the total drug concentration, thus increasing the risk of toxicity. Phenytoin is >90% protein-bound.

Question 49

Q

A teenage patient presented to the emergency department unconscious. The measured osmolality was 380 mOsm/kg, and the osmolality gap was calculated to be 30 mOsm/kg. The patient also had an ethanol level of 46 mg/dL (molecular weight 46 g/mol). The physician wanted to account for the ethanol level in order to decide if the osmolality gap could be attributed solely to the ethanol or if other toxins were present. What is the remaining osmolal gap after accounting for the contribution of ethanol, and what is the diagnosis?

A. 20mOsm/kg; gap above normal range, other toxins could be contributing to gap
B. 20 mOsm/kg; gap within normal range after accounting for ethanol
C. 16 mOsm/kg; gap above normal range, other toxins could be contributing to gap
D. 16 mOsm/kg; gap within normal range after accounting for ethanol
E. Unable to determine with the information provided

Answer

A

A. 20mOsm/kg; gap above normal range, other toxins could be contributing to gap
B. 20 mOsm/kg; gap within normal range after accounting for ethanol
C. 16 mOsm/kg; gap above normal range, other toxins could be contributing to gap
D. 16 mOsm/kg; gap within normal range after accounting for ethanol
E. Unable to determine with the information provided

The contribution of ethanol can be calculated by dividing the concentration in mg/dL by 4.6, which accounts for 10 mOsm/kg. An osmolal gap of <10 mOsm/kg is considered normal - the residual gap is still elevated and suggests other toxins on board.

Question 50

Q

Which of the following drugs would be associated with the cholinergic toxidrome?

A. naloxone
B. zolpidem
C. donepezil
D. promethazine
E. amitryptyline

Answer

A

Which of the following drugs would be associated with the cholinergic toxidrome?

A. naloxone
B. zolpidem
C. donepezil
D. promethazine
E. amitryptyline

Question 51

Q

Which set of second trimester screening results is consistent with an increased risk of Down syndrome?

AFP, 1.30 MoM; hCG, 0.65 MoM; uE3, 0.75 MoM; DIA, 1.15 MoM
AFP, 0.74 MoM; hCG, 0.65 MoM; uE3, 0.75 MoM, DIA, 0.83 MoM
AFP, 0.74 MoM; hCG, 2.06 MoM; uE3, 0.75 MoM; DIA, 1.77 MoM
AFP, 2.04 MoM; hCG, 2.06 MoM; uE3, 1.84 MoM; DIA, 1.77 MoM

Answer

A

AFP, 1.30 MoM; hCG, 0.65 MoM; uE3, 0.75 MoM; DIA, 1.15 MoM
AFP, 0.74 MoM; hCG, 0.65 MoM; uE3, 0.75 MoM, DIA, 0.83 MoM
AFP, 0.74 MoM; hCG, 2.06 MoM; uE3, 0.75 MoM; DIA, 1.77 MoM
AFP, 2.04 MoM; hCG, 2.06 MoM; uE3, 1.84 MoM; DIA, 1.77 MoM

Increased risk of giving birth to a child with Down syndrome is observed in women with elevated maternal serum concentrations of hCG and dimeric inhibin A as well as decreased AFP and unconjugated estriol relative to the institution’s median value (multiple of the median, MoM) in women of the corresponding gestational age.
It is important to remember however that no universal cutoff can be applied to all patient populations and the exact MoM used to define risk of Down syndrome varies across institutions.

Question 52

Q

How can falsely low results due to the prozone effect in quantitative immunoglobulin measurements be detected?

use of heterophile blocking tubes to remove interfering antibodies
precipitation of heterophile antibodies by pegylation
removal of excess antigen by centrifugation of patient serum
performance of sample dilution to remove antigen excess

Answer

A

How can falsely low results due to the prozone effect in quantitative immunoglobulin measurements be detected?

use of heterophile blocking tubes to remove interfering antibodies
precipitation of heterophile antibodies by pegylation
removal of excess antigen by centrifugation of patient serum
performance of sample dilution to remove antigen excess

Detection of the prozone effect requires sample dilution. Dilution of the sample removes excess antigen, allowing for proper formation of stable antigen-antibody complexes and resulting in an accurate measurement.

Question 53

Q

An individual having a clinical presentation of SLUD (salivation, lacrimation, urination, and defecation) and a depression in cholinesterase activity has been poisoned with which of the following?

A. arsenic

B. DDT

C. parathion

D. boric acid

E. mercury

Answer

A

An individual having a clinical presentation of SLUD (salivation, lacrimation, urination, and defecation) and a depression in cholinesterase activity has been poisoned with which of the following?

A. arsenic

B. DDT

C. parathion

D. boric acid

E. mercury

Question 54

Q

Patients with a buildup of serum phosphate (e.g., due to renal failure), high PTH, and chronically low serum calcium are classified as having which of the following?
A. Secondary hyperparathyroidism
B. Vitamin D intoxication
C. Tertiary hyperparathyroidism
D. Primary hyperparathyroidism
E. Ectopic PTH-producing tumor

Answer

A

Patients with a buildup of serum phosphate (e.g., due to renal failure), high PTH, and chronically low serum calcium are classified as having which of the following?
A. Secondary hyperparathyroidism
B. Vitamin D intoxication
C. Tertiary hyperparathyroidism
D. Primary hyperparathyroidism
E. Ectopic PTH-producing tumor

Due to renal failure, serum phosphate rises and is inversely proportional to calcium levels. The hypocalcemia stimulates PTH secretion and causes the parathyroid gland to synthesize more PTH as a compensation, with resultant parathyroid hyperplasia. Tertiary hyperparathyroidism is associated with conditions in which the renal failure has been treated (i.e., renal transplant, dialysis, or healing of the primary injury/disease). The parathyroid glands are occasionally not able to return to normal, with resultant hypercalcemia and high PTH.

Question 55

Q

A 58-y-old woman presents to the emergency department with chest pain. Plasma was obtained at admission, 2 h post-admission, and 6 h post-admission, and results are listed below. The most likely explanation for these results is?

Admission:

cTnI (<0.03 ng/mL), <0.03 ng/mL;
CK-MB (0–7 ng/mL), 2.4 ng/mL

2 h post-admission:

cTnI (<0.03 ng/mL), 1.65 ng/mL;
CK-MB (0–7 ng/mL), 2.5 ng/mL

6 h post-admission:

cTnI (<0.03 ng/mL), <0.03 ng/mL;
CK-MB (0–7 ng/mL), 2.3 ng/mL

The patient has suffered an acute myocardial infarction.
The patient has a heterophile antibody that causes false positive cTnI results.
The patient has not suffered an acute myocardial infarction and a sample mix-up has occurred.
The patient has a heterophile antibody that causes false positive CK-MB results.
The patient’s cTnI is not recognized by the institution’s assay.

Answer

A

The patient has suffered an acute myocardial infarction.
The patient has a heterophile antibody that causes false positive cTnI results.
The patient has not suffered an acute myocardial infarction and a sample mix-up has occurred.
The patient has a heterophile antibody that causes false positive CK-MB results.
The patient’s cTnI is not recognized by the institution’s assay.

**A sample mix-up occurred in the 2-h post-admission samples. An AMI is unlikely given these test results because increases in plasma cTnI and CK-MB occur concurrently and cTnI concentrations remain elevated for days following an AMI.

A heterophile antibody would cause consistently abnormal results rather than sporadic elevations in some samples but not others. Consistently normal CK-MB results in conjunction with normal cTnI results at admission and 6 h post admission strongly suggest that the 2-h post-admission cTnI sample was a mislabeled specimen obtained from a different patient.**

Question 56

Q

A patient presents with the following plasma laboratory values:

BUN, 6 mg/dL;
creatinine, 0.7 mg/dL;
sodium, 127 mmol/L;
potassium, 4.2 mmol/L;
osmolality, 273 mOsm/kg.
Her urine laboratory values are as follows:
- osmolality, 465 mOsm/kg;
- sodium, 48 mmol/L.

Physical examination reveals normal mucous membranes and no signs of edema. What is the most likely diagnosis?

diabetes insipidus
pre-renal fluid losses
SIADH (syndrome of inappropriate antidiuretic hormone)
congestive heart failure
dehydration

Answer

A

diabetes insipidus
pre-renal fluid losses
SIADH (syndrome of inappropriate antidiuretic hormone)
congestive heart failure
dehydration

Hyponatremia observed in conjunction with low plasma osmolality, inappropriately elevated urine osmolality, and urine sodium >40 mmol/L is most consistent with SIADH.

Question 57

Q

Which of the following laboratory findings correlate with pseudohypoparathyroidism?

a) high calcium, low phosphorus, and high PTH
b) high calcium, low phosphorus, and low PTH
c) low calcium, high phosphorus, and high PTH
d) low calcium, high phosphorus, and low PTH

Answer

A

Which of the following laboratory findings correlate with pseudohypoparathyroidism?

a) high calcium, low phosphorus, and high PTH
b) high calcium, low phosphorus, and low PTH
* *c) low calcium, high phosphorus, and high PTH**
d) low calcium, high phosphorus, and low PTH

In pseudohypoparathyroidism, calcium is low and phosphorus is elevated despite increased PTH. This is due to receptor-based PTH resistance.

Question 58

Q

The chloride from an infant’s sweat measured as 48 mEq/L. How would you interpret that result?

A. normal
B. high and suggestive of cystic fibrosis
C. low and suggestive of cystic fibrosis
D. indeterminate
E. low and not suggestive of cystic fibrosis

Answer

A

The chloride from an infant’s sweat measured as 48 mEq/L. How would you interpret that result?

A. normal
B. high and suggestive of cystic fibrosis
C. low and suggestive of cystic fibrosis
D. indeterminate
E. low and not suggestive of cystic fibrosis

Less than or equal to 29 mmol/L = CF is unlikely regardless of age

Between 30 - 59 mmol/L = CF is possible and additional testing is needed

Greater than or equal to 60 mmol/L = CF is likely to be diagnosed

Question 59

Q

A buffer pair (HA/A−) has a pK of 5.4. At blood pH of 7.4, the concentration of HA is which of the following?

A. 1/100 that of A-
B. 1/10 that of A-
C. Equal to that of A-
D. 10 times that of A-
E. 100 times that of A-

Answer

A

A buffer pair (HA/A−) has a pK of 5.4. At blood pH of 7.4, the concentration of HA is which of the following?

A. 1/100 that of A-
B. 1/10 that of A-
C. Equal to that of A-
D. 10 times that of A-
E. 100 times that of A-

The difference in pK and pH is −2.0, favoring the anionic state by 10−2, or 1:100.

Question 60

Q

How is the strength of the attraction between an individual antigen and antibody molecule characterized?

A. van der Walls Forces
B. Reactivity
C. Avidity
D. Affinity

Answer

A

How is the strength of the attraction between an individual antigen and antibody molecule characterized?

A. van der Walls Forces
B. Reactivity
C. Avidity
D. Affinity

Affinity (Avidity is the strength of interactions between many different antibodies in a serum against a particular antigen)

Question 61

Q

Once in the blood, CO2 may produce all but which substance?

HCO3
H2CO3
H+
Dissolved CO2
Lactate

Answer

A

The question of the day is: Once in the blood, CO2 may produce all but which substance?

HCO3
H2CO3
H+
Dissolved CO2
Lactate

CO2 can dissolve in H2O and combine with H2O to produce all the substances above except lactate. Lactate is an intermediate from carbohydrate metabolism.

Question 62

Q

Sweat testing is often ordered as a follow-up to a positive newborn screen for cystic fibrosis. To stimulate sweat production, which of the following methods is used?

a. thermal stimulation
b. pilocarpine iontophoresis
c. cortrosyn stimulation
d. ninhydrin stimulation
e. No stimulation is needed.

Answer

A

Sweat testing is often ordered as a follow-up to a positive newborn screen for cystic fibrosis. To stimulate sweat production, which of the following methods is used?

a. thermal stimulation
* *b. pilocarpine iontophoresis**
c. cortrosyn stimulation
d. ninhydrin stimulation
e. No stimulation is needed.

A small electrical current delivers pilocarpine nitrate into the skin (iontophoresis). Pilocarpine is cholinergic and stimulates sweat production.

Question 63

Q

What is the pH of a whole blood sample if the bicarbonate = 13 mmol/L and the pCO2 = 31 mmHg?

7.24
7.40
7.56
6.97

Answer

A

What is the pH of a whole blood sample if the bicarbonate = 13 mmol/L and the pCO2 = 31 mmHg?

7.24
7.40
7.56
6.97

pH = 6.1 + log bicarb / (pCO2 x 0.03)

Question 64

Q

Citrated plasma is mixed with silica and then incubated at 37 °C. After 3–4 minutes, calcium chloride is added and timing begins. The stopwatch is stopped as clotting commences. This describes which of the following?
A. the PT
B. the aPTT
C. the TT
D. the fibrinogen assay
E. an assay for fibrinolysis

Answer

A

Citrated plasma is mixed with silica and then incubated at 37 °C. After 3–4 minutes, calcium chloride is added and timing begins. The stopwatch is stopped as clotting commences. This describes which of the following?
A. the PT
B. the aPTT
C. the TT
D. the fibrinogen assay
E. an assay for fibrinolysis

The activated PTT is initiated by adding a negatively charged surface such as micronized silica to the plasma as well as a phospholipid extract termed “partial thromboplastin.” Recalcification of plasma occurs following several minutes of activation. The negatively charged surface activates factor XII to factor XIIa. The coagulation pathway of the aPTT represents the so-called intrinsic pathway. The latter does not appear to be completely represented in vivo. In the case of the PT, coagulation is initiated by adding an extract (thromboplastin) that is rich in tissue factor and phospholipid. Addition of thromboplastin reagent, which contains calcium, to prewarmed plasma initiates clotting through the extrinsic pathway.

Answer 65

A

A. anemia

B. anemia and pre-diabetes

C. anemia and diabetes

D. pre-diabetes

E. diabetes

Random blood glucose is 10.8 mmol/l approximately & the hba1c is 4.5%. Given his CBC report the patient has iron deficiency anemia, and this will falsely lower his HbA1c as it affects the life span of the red blood cells. So, glucose values remain the gold standard for diagnosing diabetes in such patients as well as for diabetic monitoring ( estimated average glucose or fructosamine as an alternative test ).

to diagnose diabetes values of :
fasting blood glucose > or equal to 7 mmol/l or random blood glucose of > or equal to 11.1 mmol/L , or a glucose tolerance test of fasting > or equal to 7 mmol/l or a second hour glucose value of > or equal to 11.1 mmol/l or both on oft.

An HbA1c of > or equal to 6.5% is suitable for diagnosis of diabetes if the method used is standardized and approaches with caution given patient history and drugs interference with hba1c methods.

Answer 66

A

Which of the following is an example of phase I drug metabolism?

diazepam ⇒ oxazepam glucuronide
tamoxifen ⇒ 4-hydroxytamoxifen sulfate
procainamide ⇒ N-acetylprocainamide
ethanol ⇒ acetaldehyde
norepinephrine ⇒ epinephrine

Drug metabolism is typically classified as phase I or phase II. Phase I metabolism involves nonconjugation chemical reactions (for example, oxidation/reduction or hydrolysis). A majority of these reactions are catalyzed by cytochromes P450 and esterases. Phase II metabolism involves the conjugation of xenobiotics with various species (for example, glutathione, sulfate, glycine, or glucuronic acid). In general, these biotransformations tend to produce hydrophilic metabolites that can be excreted in the urine.

Answer 67

A

Which of the following tests would be expected to have an increased value for a patient with iron deficiency anemia?

TIBC
ferritin
hemoglobin
iron saturation

Iron-deficiency anemia (IDA) is diagnosed by blood tests including a complete blood count (CBC) and evaluation of iron status. Tests performed to evaluate a patient’s iron status may include: serum ferritin, iron, total iron-binding capacity (TIBC) and/or transferrin, and iron saturation. Individuals with IDA typically have decreased values for hemoglobin (Hg), hematocrit (Hct), mean cellular volume (MCV), ferritin, iron, and iron saturation; but have an increased value for transferrin/TIBC.

Answer 68

A

A 25-y-old woman presents with bilateral hemianopsia and amenorrhea. Magnetic resonance imaging (MRI) shows a pituitary mass. The patient’s HMO allows you to draw only one test of pituitary functions at this time. What is the best single test to draw? If this test is normal, the HMO will allow further testing.

*a. Prolactin**
b. GH
c. ACTH
d. alpha-subunit
e. LH

Women with a pituitary mass may have a pituitary tumor, which can result in hyperprolactinemia. High prolactin is associated with amenorrhea, galactorrhea, and visual field disturbances (hemianopsia).

Answer 69

A

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by which of the following?
A. Hyponatremia
B. Hypovolemia
C. Urine sodium < 20mmol/L
D. Urine osmolality lower than serum osmolality

Dilutional hyponatremia

Answer 70

A

A patient at steady-state on 0.10 mg/kg/day tacrolimus has his dose increased to 0.15 mg/kg/day. If the half-life is 21 hours, how long after his first 0.15 mg/kg/day dose until a new steady-state concentration is reached?

A.21 hours

B. 42 hours

C. 3 days

D. 5 days

E. 10 days

5-7 half lives to reach steady state so between 4.5 and 6 days. 5 days likely the best answer.

Answer 71

A

Pigmented casts with a red-brown coloration are suspicious for which of the following?

pre-renal acute renal failure
glomerulonephritis
acute tubular necrosis
tubulointerstitial nephritis
bladder pathology

The primary cause of acute tubular necrosis is myoglobin excretion in rhabdomyolysis - it is the myoglobin that gives the red-brown pigment to the casts.

Pre-renal causes of acute renal failure are associated with increased hyaline casts.

Glomerulonephritis would increase red blood cell casts.

Tubulointersitial nephritis is suggested by the presence of eosinophils in urine.

Bladder pathology does not associate with cast formation - typically whole erythrocytes and epithelial cells are increased instead.

Answer 72

A

An elevated NT-proBNP level in a pleural effusion may be associated with which of the following?

liver cirrhosis
heart failure
purulent pleuritis
rheumatoid arthritis

Answer 73

A

A normal response to a water deprivation test in the investigation of suspected diabetes insipidus is which of the following?

a. increased urine and plasma osmolality
b. increased urine osmolality and reduced serum osmolality
* *c. increased urine osmolality and no change in plasma osmolality**
d. reduced urine osmolality and reduced serum osmolality

In a healthy subject, the urine becomes concentrated in response to water deprivation and plasma osmolality does not exceed 295  mmol/kg. In diabetes insipidus, the urine does not become concentrated and plasma osmolality rises..

Answer 74

A

In the context of mass spectrometry, a soft ionization technique such as chemical ionization….

A. produces predominantly molecular ions with little fragmentation.
B. produces few molecular ions and predominantly fragments.
C. produces unstable adduct ions that break down into fragments.
D. allows small compounds to become multiply charged for better resolution.
E. allows larger compounds to become multiply charged for better resolution.

Answer 75

A

Measurement of carbohydrate-deficient transferrin in plasma is used to identify which of the following?

A. alcohol consumption

B. chronic hypoglycemia

C. iron deficient anemia

D. iron overload

E. liver dysfunction

Answer 76

A

Subjects A and B are both healthy 70-kg men. Subject A drinks 2 L of distilled water, and subject B drinks 2 L of isotonic saline. As a result of these ingestions, Subject B will have which of the following?

Higher urine osmolality
Greater change in intracellular fluid volume
Higher positive free-water clearance
Greater change in plasma osmolality
Higher urine volume

By drinking 2 L of fluid, both subjects expand their circulating volume. By drinking distilled water, Subject A would also decrease plasma osmolality. However, Subject B’s consumption of saline should not change plasma osmolality. The result in both subjects would be excretion of an increased volume of urine, but the osmolality would differ. Subject A’s urine would have low osmolality, and Subject B’s urine would be of normal osmolality.

Answer 77

A

What is the best interpretation of a patient with microalbuminuria?

end-stage renal disease
nephrotic disease
diabetic nephropathy
glomerulonephritis

In diabetics, urine albumin concentrations become abnormal before there is overt renal disease. About one-third of type 1 diabetics will develop nephropathy, requiring dialysis or transplantation. Treatment of patients with microalbuminuria may be useful in reducing the progression or severity of the disease. Other answer options in this question would result in overt proteinuria rather than the small amount of albumin in the urine found in microalbuminuria. Microalbuminuria may also be seen in early chronic renal disease (stages 1 and 2).

Answer 78

A

An exudate contains which of the following?

*a. protein fluid/serum ratio > 0.5**
b. protein fluid/serum ratio < 0.5
c. high glucose concentration relative to serum
d. only albumin; proteins of high relative molecular mass are excluded
e. only proteins of high relative molecular mass; albumin is excluded

Answer 79

A

Decreased plasma methionine and increased plasma homocysteine may be observed in:
A. Cystathionine beta synthase deficiency (Classic Homocystinuria)
B. Methylmalonyl-CoA mutase deficiency
C. Methionine adenosyl transferase deficiency
D. Defects in folate recycling or B12 metabolism

Answer 80

A

Which statement regarding multiple myeloma (MM) patients with urinary free immunoglobulin light chains is correct?

A. They are at increased risk for hyperviscosity syndrome.
B. They are at decreased risk of renal failure.
C. Presence of these Bence-Jones proteins can cause renal insufficiency.
D. They typically have a lower incidence of bone lesions.
E. Presence of free light chains leads to cryoglobulinemia.

Answer 81

A

A laboratory performs 10,000 reportable tests for thyroid-stimulating hormone (TSH) per year using an automated immunoassay analyzer. Each run requires 30 minutes to test controls and 100 patient samples. Calibration is performed every month and requires an additional 30 minutes. The hourly MT labor costs are $15.00/hour plus 30% for benefits. The instrument rents for $10,000/year, and requires a $5,000/year service contract. What is the sum of labor and indirect costs?

$11,092
$15,840
$16,092
$16,840
$16,992

To report 10,000 samples, 100 runs are required, plus 12 calibrations. This requires a total of 56 hours. The hourly labor rate plus benefits is $19.50. The yearly labor cost is $1,092. This is added to the instrument costs and service contract: $10,000 + $5,000 + $1,092 = $16, 092.

Answer 82

A

A patient’s SPEP reveals a 2.1 g/dL band that is demonstrated to be a monoclonal IgM-κ by immunofixation.
Which of the following diagnoses is most likely?

MGUS
IgM myeloma
non-Hodgkin’s lymphoma
Waldenström macroglobulinemia

Monoclonal IgM paraproteins may be seen in Waldenström macroglobulinemia, non-Hodgkin lymphoma, and MGUS. However, a paraprotein concentration greater than 2.0 g/dL would be commonly found only in Waldenström macroglobulinemia. IgM myeloma is rare, and most purported cases of it are better classified as Waldenström macroglobulinemia.

Answer 83

A

Of the following serum immunoglobulins, which may cause β-γ bridging?

IgG
IgA
IgM
IgD
IgE

Answer 84

A

Disorders producing insulin antagonists, and therefore a secondary diabetes, include all of the following EXCEPT:

A. Cushing’s syndrome
B. Pheochromocytoma
C. Hypothyroidism
D. Acromegaly
E. Glucagonoma

Glucagon, Cortisol, Epinephrine, Growth hormone antagonizes actions of Insulin.

Answer 85

A

Which of the following is true regarding transferrin?

It is an α1-globulin.
It binds 20% of serum iron.
It increases with acute inflammation.
It binds ferric (Fe3+) ions.

Transferrin, a plasma beta globulin (molecular weight 79.5 kDa), binds up to two ferric (Fe3+) ions. Ferrous iron will not bind to transferrin. Transferrin actually decreases with inflammation and is sometimes termed a “negative acute-phase reactant.” There is no free iron in serum.

Answer 86

A

Which of the following ketone bodies is generally expected to be in the greatest proportion in blood?

a) acetone
b) acetoacetic acid
* *c) β-hydroxybutyric acid**

β-Hydroxybutyric acid averages 78% of blood ketones. Acetoacetic acid increases as diabetic ketoacidosis is resolved, while acetone increases as diabetic ketoacidosis worsens.

Answer 87

A

Which of the following is the main pathologic event in heparin induced thrombocytopenia (HIT)?

Antibodies directed against a heparin/platelet factor 4 (PF4) complex
Damaged endothelial cells
High levels of antithrombin III
High levels of D-dimer
Continuous exposure to heparin for 24 hours

Answer 88

A

Hb S is the result of a substitution of which amino acid and position of the Hb β-globin chain?

a. valine, 6
b. glycine, 21
c. tyrosine, 102
d. leucine, 12
e. cysteine, 36

Answer 89

A

Which of the following describes the cathode in an electrochemical cell?
A. Loss of electrons occurs; reduction
B. Gain of electrons occurs; reduction
C. Loss of electrons occurs; oxidation
D. Gain of electrons occurs; oxidation

Answer 90

A

This is most compatible with which of the following?

A) iron deficiency anemia
B) anemia of chronic disease
C) hemochromatosis
D) thalassemia trait
E) liver disease

Thalassemias are a consequence of reduced synthesis of one of the globin polypeptide chains in hemoglobin, which causes an imbalance in chain production. The unaffected globin chain is produced in excess relative to the affected chain, which leads to the clinical presentation. Excess globin chains precipitate, denature, and undergo oxidation, resulting in damage to RBCs, ineffective erythropoiesis, and anemia.
In thalassemia, iron studies may be normal or show iron overload. Affected individuals have moderate to marked microcytosis, and in milder thalassemia, the red cell count is often increased.

Answer 91

A

A young adult male presents to the ER with a history of new-onset seizures. The glucose at the time of the seizure was 109 mg/dL, Ca+2 was 6.0 mg/dL (RI 8.4-10.2 mg/dL), normal albumin and alk phos. PO4-3= 7.0 mg/dL (RI 3-4.5 mg/dL). What test should be ordered next to determine the cause?
A. 25-hydroxyvitamin D
B. 1,25-dihydroxyvitamin D
C. intact PTH
D. calcitonin
E. insulin

Answer 92

A

To perform mass analysis:

A. Compounds must be positively charged
B. Compounds must be negatively charged
C. Compounds must be fragmented to form an identifiable mass spectrum
D. Compounds must be a gaseous state
E. Compounds must be separated in a positive pressure environment

To perform mass analysis:
A. Compounds must be positively charged - can be negative ionisation mode as well
B. Compounds must be negatively charged - can be positive ionisation mode as well
C. Compounds must be fragmented to form an identifiable mass spectrum - no absolute need for fragmentation, eg, TOF, single quadrupole MS do not require collision/fragmentation
D. Compounds must be a gaseous state - during the stage of ionisation, compounds will have to become gaseous ions before entering the mass spectrometer
E. Compounds must be separated in a positive pressure environment - mass spectrometer chamber itself requires vacuum.

Answer 93

A

Which of the following is true regarding Helicobacter pylori antigen testing?

a. It should be performed on gastric biopsies.
b. It is less sensitive than antibody testing.
c. It can be useful for both diagnosis and monitoring therapeutic response.
d. It is not useful for diagnosis of infection in the elderly.

H. pylori-positive patients shed antigen in their stool. The antigen assay is a noninvasive means for detecting positive patients and for monitoring therapeutic response 1 month after completing treatment. Many serological tests have suboptimal sensitivity and specificity. The stool antigen test and the urea breath test are currently the most accurate noninvasive diagnostic tools for the diagnosis of H. pylori infection and are preferable to the use of serological tests.

Answer 94

A

Which of the following is the most abundant intracellular cation?

*a) potassium**
b) sodium
c) calcium
d) magnesium

Answer 95

A

How does multiple myeloma (MM) differ from Waldenstrom macroglobulinemia (WM)?

A) fewer lytic lesions and less bone main with MM
B) lower incidence of serum hyperviscosity in MM
C) fewer recurrent bacterial infections with MM
D) higher incidence of monoclonal IgM in MM
E) more visual disturbances with MM

MM differs from WM in multiple ways - WM is a monoclonal IgM gammopathy, while IgM gammopathy is relatively rare (~1%) in MM.
Compared to MM, WM typically exhibits

Fewer lytic lesions and less bone pain,
higher incidence of serum viscosity,
higher incidence of visual changes and retinal hemorrhage due to serum hyperviscosity
fewer bacterial infections.

Answer 96

A

What is/are the predominant lipoprotein(s) to be elevated in Fredrickson phenotype IV?

1. Chylomicrons
2. VLDL
1. Chylomicrons and VLDL
1. LDL
1. LDL and VLDL

Bonus question: how can you differentiate Type IV from Type I without additional lab testing?

Refrigeratory test which leads, after 24 h, to a creamy supernatant in Type I owing to the presence of chylomicrons.

Answer 97

A

The overall effect of parathyroid hormone is to do which of the following?

a. decrease calcium while also lowering plasma phosphate concentration
b. increase calcium while lowering plasma phosphate concentration
c. increase calcium while raising plasma phosphate concentration
d. decrease calcium with no effect on plasma phosphate concentration
e. increase calcium concentration with no effect on plasma phosphate concentration

Parathyroid hormone raises plasma calcium concentrations. However, parathyroid hormone reduces expression of the sodium-dependent phosphate co-transporter, resulting in lowering of phosphate concentrations. The overall effect is therefore raising the circulating calcium concentration while lowering the phosphate concentrations.

Answer 98

A

A blood urea nitrogen concentration (BUN) reported as 120 mg/L is equal to how many milligrams of urea per liter?

a) 56
b) 257
c) 510
d) 600

Urea is a molecule, with a molecular weight of 60, composed of two ammonia groups connected by a carbonyl group. Blood urea nitrogen methods measure the amount of ammonia nitrogen present, which is part of the molecule rather than the total urea molecule. The nitrogen in the urea has a molecular weight of 28. Thus, 120 mg/L × (60 mg/L ÷ 28 mg/L) = 257 mg/L. Or another way of thinking of it: The nitrogen weight of 28 is 46.7 % of the urea weight of 60. Thus 120 mg/L ÷ 0.467 = 257 mg/L.

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