Chemistry

Question 1

What is the function of cystatin C

Answer 1

Measure GFR

*Endogenous substances used to determine GFR are urea nitrogen, creatinine and cystatin C

Question 2

Pt has low serum cholinesterase level–what is next step in workup?

Answer 2

Test if cholinesterase can be inhibited by dubicaine

**In hereditary hypocholinesterasemia, cholinesterase will not be inhibited by dubicaine

Question 3

Most common drug to cause drug-induced lupus?

Answer 3

procainamide

Question 4

Which lipid tests are invalid if patient is not fasting?

Answer 4

triglycerides and calculated LDL

Question 5

Where is DHEA-S produced?

Answer 5

adrenals

Question 6

What type of bilirubin is water insoluble and bound to albumin in blood?

Answer 6

Unconjugated (indirect)

Question 7

What type of bilirubin is water soluble?

Answer 7

conjugated (direct)

Question 8

4 diagnostic criteria for DM

Answer 8

HbA1c >6.5%
FPG >126
OGTT 2 hr >= 200 (75g ora glucose load)
Random plasma glucose >=200

Question 9

Which patients have macro CK type 1?

Answer 9

healthy elderly women

Question 10

Which patients have mitochondrial CK (macro-ck type 2)?

Answer 10

advanced malignancy

Question 11

What does prealbumin bind in the serum?

Answer 11

thyroxine (aka transthyretin)

retinol binding protein: vitamin A complex

Question 12

Causes of pseudo M-spike on SPEP?

Answer 12

Fibrinogen (incompletely clotted sample
hemoglobin (hemolyzed sample)
elevated CRP
elevated transferrin (beta area)
Medicaitons (antibiotics, radiocontrast agents)
Serum tumor markers (e.g. CA 19-9)

Question 13

Define type 1 cryoglobulin

Answer 13

monoclonal immune globulin associated with MM or waldenstrom

Question 14

Define type 2 cryoglobulin

Answer 14

mixture of monoclonal IgM and polyclonal IgG; IgM has rheumatoid factor activity (anti-IgG)
-most common type

Question 15

Define type 3 cyroglobulin

Answer 15

mix of two polyclonal Ig’s, typically IgG and IgM; IgM has rheumatoid factor activity

Question 16

What is the most common cause of mixed cryoglobulinemia (type 2+3)

Answer 16

HCV
Sx include leukocytoclastic vasculitis, arthralgia, LAD hepatosplenomegaly, anemia, sensorineural hearing deficits, MPGN type II

Question 17

what medical conditions can cause pseudohyponatremia?

Answer 17

hypertriglyceridemia
hypercholesterolemia
hyperproteinemia
(due to decreased water content of plasma)

Question 18

What cancers can secrete PTHrp?

Answer 18

SCC lung, head and neck, skin ,cervix and esophagus
breast ca
T cell lymphoma

Question 19

What forms of PTH are biologically active?

Answer 19

intact PTH
N-terminal PTH
-rapidly cleared from blood T1/2=5 mins

Question 20

What is cause of increased BUN/creatinine ratio?

Answer 20

normal 10:1, if greater than 20:1 prerenal azotemia (due to hypoperfusion)

Question 21

Most common cause of false pos b-hCG

Answer 21

heterophile antibodies

Question 22

Quad screen showing low AFP, low uE, raised hCG and raised DIA

Answer 22

Trisomy 21 (Downs)

Question 23

Quad screen showing low AFP, hCG and uE

Answer 23

Trisomy 18 (edwards)

Question 24

Quad screen showing elevated AFP, normal hCG and low uE

Answer 24

NTD

Question 25

What is metabolite of serotonin (5-HT) that is produced by carcinoids?

Answer 25

5 hydroxyindoleacetic acid (5-HIAA) | excreted in urine

Question 26

What do foregut carcinoids produce?

Answer 26

histamine, catecholamines, 5 hydroxytryptophan (5-HTP)

Question 27

What do midgut carcinoids produce?

Answer 27

serotonin only

Question 28

What do hindgut carcinoids produce?

Answer 28

usually nothing! non-secretory

Question 29

VMA is a metabolite of what

Answer 29

norepi-->normetanephrine-->vanillylmandelic acid (VMA) | epi-->metanephrine-->VMA

Question 30

What two metabolites are elevated in neuroblastoma?

Answer 30

VMA and HVA (homovanillic acid; final breakdown product of dopamine)

Question 31

At what time points does cortisol trough and peak?

Answer 31

Trough midnight | Peak 8am

Question 32

TWO MOST COMMON CAUSE CONGENITAL ADRENAL HYPERPLASIA

Answer 32

1. 21-HYDROXYLASE DEFICIENCY | 2. 11-HYDROXYLASE DEFICIENCY

Question 33

What is responsible for the majority (70%) of kidney stones?

Answer 33

Calcium oxalate

Question 34

What metabolite is elevated in CAH

Answer 34

17 hydroxyprogesterone

Question 35

Increased osmolar gap but normal anion gap. What ingested?

Answer 35

isopropanol

Question 36

osmolar gap calcuation

Answer 36

osmolal gap=osmolarity measured-osmolarity calculated =osmolarity measured-(2[Na]+glucose/18+BUN/2.8) *normal=10

Question 37

Anion gap calculation

Answer 37

anion gap=Na-(Cl+HCO3)

Question 38

Causes if metabolic acidosis with increased anion gap?

Answer 38

MUDPILES | methanol, uremia, DKA, paraldehyde, lactic acidosis, ethylene glycol, salicylate

Question 39

Causes if metabolic acidosis with normal anion gap?

Answer 39

diarrhea, ureterosigmoidoscopy, NH4Cl, carbonic anhydrase inhibitors, TPN, RTA

Question 40

2 potential causes of increased osmolar gap and increased anion gap?

Answer 40

Methanol or ethylene glycol

Question 41

What inhibits prolactin secretion?

Answer 41

Dopamine

Question 42

Patient with elevated serum osmolarity, elevated serum sodium, and low urine osmolarity. When they are given a dose of ADH, their urine becomes concentrated (osmolarity increases from ~100 to ~700 mOsm/kg). What do they have?

Answer 42

Central diabetes insipidus

Question 43

Patient with lung disease with decreased serum osmolarity, decreased serum sodium, and elevated urine osmolarity. What do they have?

Answer 43

SIADH

Question 44

Which drug has benzoylecgonine as a metabolite

Answer 44

cocaine

Question 45

Which HLA types are associated with T1DM

Answer 45

HLA-DR3 | HLA-DR4

Question 46

Which HLA types are associated with celiac

Answer 46

HLA-DQ2 95% | HLA-DQ8 5%