Quiz 2 Hormone Tests Flashcards Preview

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Flashcards in Quiz 2 Hormone Tests Deck (15)
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ADH stimulation test

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


Screen for pheochromocytoma in adrenal medulla

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


Functional Tests For Adrenal Cortex Status

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


ACTH Stimulus test

ACTH iv, follow rise in cortisol at 1 h


Metyrapone Stimulation Test

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


Dexamethasone Suppression Test

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


Mineralocorticoid Function Tests

-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.


Addison's Tests

ACTH, Aldosterone, Cortisol Levels


Cushing's Tests

Cortisol, Dexamthasone Suppression


Thyroid testing in serum

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


Thyroid Function Tests

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


Thyroid Iodine Uptake

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


TRH Stimulation Test

TRH iv monitor increase in TSH, T4 and T3.


TSH Stimulation Test

TSH iv monitor T4 and T3 levels


T3 Suppression Test

Radioiodide uptake before and after T3 po dose.