Mosby CLIs Flashcards
Indications for Urine Glucose Test
Part of routine urinalysis, can also monitor effectiveness of therapy for diabetes mellitus
What are other tests that can confirm a suspected diagnosis w/ a positive urine glucose test
Fasting glucose, glucose tolerance, glycosylated hemoglobin
What normally filters glucose from the blood
Glomeruli of the kidney, reabsorbed in proximal renal tubules
What is the renal threshold to reabsorb the glucose
180 mg/dL
Associated w/ transport defects in the proximal renal tubules causing lgucosuria - genetic defect that can also affect the metabolism and excretion of amino acids and electrolytes
Fanconi syndrome
Indication for Nerve conduction study
To identify peripheral nerve injury in patients w/ localized or diffuse weakness, muscle atrophy, dysethesia, paresthesia, and neurogenic pain
Can document severity of injury
Where is the electrical impulse of a nerve conduction study placed to evaluate motor nerves? Sensory nerves?
Motor: proximal
Sensory: distal
What study is done in conjunction w/ a Nerve Conduction Study
EMG - electromyoneurography
What is normal conduction velocity for upper extremities? Lower extremities?
UE: 50-60
LE: 40-50
What could a slower conduction velocity be indicative of? Faster conduction? No conduction?
Slower: trauma, contusion, neuropathies
Faster: pathologic condition not indicated
None: complete nerve transection
How is muscular factor evaluated in a nerve conduction study?
Measuring distal latency (time required for stimulation of nerve to cause muscular contraction)
Equation for nerve conduction study
Conduction velocity = Distance/(Total-Distal Latency)
Vitamin B1
Thiamine
Vitamin B2
Riboflavin
Vitamin B3
Niacin
Vitamin B4
Pantothenic Acid
Vitamin B6
Pyridoxine
Vitamin B7
Biotin
Vitamin B9
Folate
Vitamin B12
Cyanocobalamin
Vitamin C
Ascorbic Acid
Vitamin A
Retinol
Vitamin D
25-Hydroxy vitamin D
Vitamin E
Alpha-tocopherol
Vitamin K1
Aqua-Mephyton
Indication for Vitamin B12 testing
Identify cause of megaloblastic anemia, used in evaluation of malnourished
Vitamin B12 is necessary for conversion of inactive form of ___ to active form
This is necessary for formation of ___ and for synthesis of ___ and ____
folate
RBCs
Nucleic acids, amino acids
How many months of Vitamin B12 depletion are needed before anemia occurs
6-18 months
What are the main sources of Vitamin B12
Meat, eggs, dairy
What is necessary for B12 absorbtion
Intrinsic factor
Top cause of vitamin B12 defiency? Next most common cause? Third most common?
Intrinsic factor deficiency
Lack of gastric acid
Malabsoption
What does serum B12 measure?
Recent B12 ingestion
What is a better measure of prolonged B12 defiency?
urinary methylmalonic acid (MMA)
The active form of B12 is essential in the itnracellular conversion of ___ to ___
L-methylmalonyl coenzyme A (MMA CoA)
Succincyl CoA
W/o B12, MMA CoA is metabolized to ____ which is excreted by ____
MMA
Kidneys
Critical Values of Magnesium
9 mEq/L
Where is magnesium found in the body?
Most intracellularly, about half in bone, most bound to ATP and is important in phosphorylation of ATP
___, ____, and ___ synthesis depend on Magnesium
Carbohydrate, protein, nucleic acid
Low magnesium may increase cardiac ___ and aggravate cardiac ____
irritability, arrhythmias
Hypermagnesmia retards
neuromuscular conduction
How is cardiac conduction slowing visible in magnesium excess
Widened PR and QT intervals, wide QRS
Diminished deep tendon reflexes, respiratory depression
Which 3 positively charged elements are used intracelllularly
Potassium, Magnesium, Calcium
magnesium increases the intestinal absorption of
calcium
Alcohol abuse increases ____ in the urine
magnesium loss
Moderate hypomagnesmia occurs w/ ___,___,___, and ___ or __ in pregnancy
diabetes, hypoparathyroidism, hyperthyroidism, hyperaldosteronism
toxemia
What are increased magnesium levels most commonly associated w/
ingestion of magnesium-containing antacids
or chronic renal disease
Lysis of RBCs results in
Falsely high quantities of magnesium into the blood
Increased Magnesium caused by
renal insufficiency, Addison disease, Ingestion of antacids or salts, hypothyroidism
Decreased Magnesium caused by
Malnutrition, malabsorption, hypoparathyroidism, alcholism, chronic renal tubular disease, diabetic acidosis
Indication of GH testing
Used to indentify GH deficiency in adolescents w/ short stature, delayed sexual maturity
gigantism or acromegaly
Stimulates GH release from pituitary
Hypothalamus secretes growth hormone-releasing hormone
What is the most commonly tested somatomedin
somatomedin C
Where is somatomedin C produced and what does it effect
liver
cartilage
High levels of somatomedins stimulate the production of
somatostatin from the hypothalamus
When is GH secreted
sleep, exercise, ingestion of protein, response to hypoglycemia
In total absence of GH, linear growth occurs at ___ of normal rate
1/2 to 1/3 of normal rate
Why are random assays for GH not adequate determinates of GH deficiency/excess
GH secretion is episodic
Should be drawn 60-90 minutes after deep sleep or 30 minutes after exercise
Why is IGF not helpful in suspected GH deficiency
Levels are affected by nurtirional status, liver and thyroid function, and age
What test is used in suspected GH deficiency
GH stimulation test
What test is used to identify gigantism or acromegaly
Growth hormone suppression test - oral glucose tolerance test
Indications for Somatomedin (IGF-1)
Used to identify patients w/ growth hormon deficiency, pituitary insufficiency, and acromegaly
How do somatomedins and GH differ
do not vary by time of day, food intake, or exercise because they are bound to proteins and are durable or long-lasting
What are some nonpituitary causes of reduced IGF-1 levels
malnutrition, severe chronic illnesses, sever liver disease, hypothyroidism, renal failure, IBS, Laron dwarfism
Is less age dependent and is more accurate w/ 97% specificity and sensitivity
IGF BP3
Why is thyroxine tested in patients w/ short stature?
Rule out hypothyroidism
Why is somatomedin C, GH, and GH stimulation tested in patients w/ short stature?
Rule out GH deficiency
Why are xray films of wrists tested in patients w/ short stature
To Document growth retardation
Why is calcium tested in patients w/ short stature?
Rule out pseudohypoparathyroidism
Why is phosphate tested in patients w/ short stature
rule out rickets
Why is bicarb tested in patients w/ short stature
rule our renal tubular acidosis
Why is BUN tested in patients w/ short stature
rule our renal failure
Why is BC tested in patients w/ short stature
Rule out anemia or nutrition/chronic disorders
Why is sedimentation rate tested in pt. w/ short stature
rule out IBS
Why is chromosomal karyotype tested in patients w/ short stature
Rule out chromosomal abnormalities
Indication for glycosylated hemoglobin test
used to diagnose and monitor diabetes treatment, measures amount of HbA1c in blood and provides a long term index of patient’s average blood glucose levels
98% of hemoglobin in RBC is in what form
Hemoglobin A, 7% of this is HbA1
What are the 3 components of HbA1
A1a, A1b, A1c
Which component of HbA1 binds w/ glucose and is the most accurate measurement of glycosylated hemoglobin
A1c
Benefit of Glycosylated hemoglobin testing? Negative of testing?
Can be drawn regardless of recent meal
Doesn’t reflect acute changes in glucose usage
What provides a more recent measurment of glucose levels aside from glycosylated hemoglobin testing
Glycated protein or fructosamine testing (shorter half-lives)
What are the two tests to confirm diabetes mellitus
but what does Diabetes federation say can be used instead?
fasting blood glucose and GTT
2 abnormal GHb assays
GHb levels can be correated w/
mean plasma glucose levels via
MPG = (35.6*GHb) - 77.3
Correlation between GHb and MPG if A1c is below 6% and MPG is below 135
Nondiabetic range
Correlation between GHb and MPG if A1c is 8% and MPG is 205
action suggested
Indication for glucose tolerance test
used to assist in diagnosis of diabetes mellitus
How will a patient w/ diabetes react to oral glucose test
serum glucose levels will be greatly elevated for 1-5 hours post administration, glucose may be present in urine
What are the levels of glucose needed to diagnose Gestational diabetes at the following times: (2 or more) fasting 1 hour 2 hour 3 hour
105
190
165
145
O’ Sullivan’s test
pregnant women tested between 24-28 weeks w/ 50g dose of glucose
Indications for Postprandial glucose test
measurement of glucose in patients blood 2 hoours after a meal is ingested - used to diagnose diabetes mellitus
What range of results from a PPG test are indicative of PPG
greater than 200
Critical levels of Glucose M/F
M: 450
F: 450
What two substances control glucose levels
insulin and glucagon
Where is glucagon produced
alpha cells of pancreatic islets of Langerhans
Indications for blood cortisol test
measure of serum cortisol - performed in pt. w/ suspected hyper/hypo functioning adrenal glands
Corticotropin-releasing hormone is made in ____ and stimulates ___ production in the ____
hypothalamus
ACTH
Anterior pituitary gland
ACTH stimulates the ____ to produce cortisol which has a negative feedback on ___ and ___
adrenal glands
CRH and ACTH
When are cortisol levels highest? lowest?
6-8am
midnight
DIURINAL Variation
What are high levels of cortisol indicative of? Low levels?
cushing syndrome
addison syndrome
Indication for complement assay
to diagnose hereditary deficiencies of complement peptides and monitor activity of infectious or autoimmune diseases
What is the main function of total complement
increase vascular permeability
The absence of early components C1-C4 has what effect?
inability of complement immune complexes to activate the cascade - unable to clear immune complexes
Absence of late componets C5-9 has what effect?
Inability to form MAC - increased susceptibility to infections w/ encapsulated microorganisms
What is the most common inherited complement deficiency
C2
What usually causes acquired complement deficiencies
Ongoing inflammatory/infectious diseases
Why do complement assays need to be frozen immediately
C3 is very unstable at room temp
Indication for AChR test
diagnose acquired myasthenia gravis and to monitor patient response to immunosuppressive therapy
Disease in which antibodies block/destroy receptors for ACh leading to muscle weakness and fatigue
myasthenia gravis
The AChR binding antibody can activate compliment which leads to
loss of AChR
AChR modulating antibody causes
receptor endocytosis resulting in loss of AChR expression
What is the most commonly used method for detection of AChR antibodies
Quantitative Radioimmunoassay/Semi-Quantitative Radioreceptor Assay
Anti-Striated Muscle antibody titers greater than 1:80 indicative of
myasthenia gravis
can be found in rheumatic fever, MI, post-cardiotomy states
