Quiz 2 Hormone Tests

Question 1

ADH stimulation test

Answer 1

Overnight water deprivation test
•Dehydration stimulates ADH release
•Measure plasma and urine osmo at start and end of 24 hour fast.

Question 2

Screen for pheochromocytoma in adrenal medulla

Answer 2

Urinary Metanephrine Test:
• False positive metanephrine urine: stress, certain medications (MAO Inhibitors, antidepressants)
• Vanillylmandelic Acid (VMA) and total catecholamine 24 h urine are also used. These test are less sensitive but are more specific.
Clonidine suppression test:
Clonidine (an adrenergic blocker drug) given as a suppression test -> inhibits release of catecholamines in normal patients but not in patients with a adrenal tumor.
Measured before and 3hrs after test

Question 3

Functional Tests For Adrenal Cortex Status

Answer 3

Measure circulating levels of:
-CRH (a hypothalamic polypeptide) 
-ACTH (a pituitary peptide)
-Cortisol levels
ACTH Stimulus test:
Metyrapone Stimulation Test
Dexamethasone Suppression Test

Question 4

ACTH Stimulus test

Answer 4

ACTH iv, follow rise in cortisol at 1 h

Question 5

Metyrapone Stimulation Test

Answer 5

Metyrapone inhibits the rate limiting enzyme in cortisol synthesis
Inject drug, inhibit cortisol (confirm with plasma levels)
Measure rise in ACTH as normal response.

Question 6

Dexamethasone Suppression Test

Answer 6

Dexamethasone is a synthetic cortisol analog Measure cortisol and ACTH suppression Tumors show no suppression

Question 7

Mineralocorticoid Function Tests

Answer 7

• Measure aldosterone levels
• Measure renin-angiotensin-aldosterone system levels
• Stimulate with diuretic (furosemide) po or iv. Blood volume loss will stimulate sodium retention and aldosterone increase.

Question 8

Addison’s Tests

Answer 8

ACTH, Aldosterone, Cortisol Levels

Question 9

Cushing’s Tests

Answer 9

Cortisol, Dexamthasone Suppression

Question 10

Thyroid testing in serum

Answer 10

Uptake tests (radioimmunoassays)
• T3/T4 Uptake: pt sample + tagged T3/T4
• The binding of available sites in pt’s sample occurs; and the resulting amount of tagged hormone that remains is inversely proportional to available binding sites

Question 11

Thyroid Function Tests

Answer 11

• Thyroid Iodine Uptake
• TRH Stimulation Test
• TSH Stimulation Test:
• T3 Suppression Test

Question 12

Thyroid Iodine Uptake

Answer 12

(123)I dose, count radioactivity of thyroid 4 - 24 h post 200 uCi dose. Checks functional status of the thyroid to produce hormone.

Question 13

TRH Stimulation Test

Answer 13

TRH iv monitor increase in TSH, T4 and T3.

Question 14

TSH Stimulation Test

Answer 14

TSH iv monitor T4 and T3 levels

Question 15

T3 Suppression Test

Answer 15

Radioiodide uptake before and after T3 po dose.