Endocrine Labs & Diagnostic Tests Flashcards
What is considered the “Master Gland” of the endocrine system?
The pituitary gland
What hormones are produced by the posterior pituitary?
ADH
Oxytocin
What hormones are produced by the anterior pituitary?
TSH ACTH FSH & LH Growth hormone Prolactin Endorphins
What is the target organ that TSH acts on?
Thyroid
What is the target organ that ACTH works on?
Adrenal cortex
What hormone, released by the hypothalamus, acts on the anterior pituitary?
CRF (corticotropin-releasing factor)
What happens when the HPA axis responds to stress?
Stress triggers the hypothalamus to release CRF –> CRF acts on the anterior pituitary to release ACTH–> ACTH acts on the adrenals (adrenal cortex) to release cortisol into the circulation
What hormone, released by the anterior pituitary, acts on the adrenals?
ACTH (adrenocorticotropic hormone)
Describe the adrenal glands
Glands that sit on each kidney. An outer cortex surrounds the inner medulla.
What is the purpose of ADH (antidiuretic hormone)?
Regulator of “pure” water supply (through excretion or retention)
What is the body’s ADH response to high plasma osmolality?
Increase ADH–> increases pure water retention –> increases blood volume to equalize plasma osmolality
What hormones are secreted by the thyroid?
Thyroxine (T4), triiodothyronine (T3), and calcitonin
What does PTH (parathyroid hormone), made by the parathyroid, regulate in the blood?
Calcium and phosphorous levels
What is the water deprivation test (also called an ADH stimulation test) used for?
It is used to differentiate causes of diabetes insipidus. It is a type of pituitary study
3 causes of diabetes insipidus
- Neurogenic
- Nephrogenic
- Psychogenic polydipsia
How is a water deprivation test (ADH stimulation test) performed?
- ADH (vasopressin) administered exogenously
2. Monitor: urine output, urine specific gravity, & serum osmolality every hour/2 hours during the test
List the adrenal diagnostic tests
- Cortisol, aldosterone, ACTH serum levels
- Urine cortisol (24 hour urine)
- ACTH stimulation & suppression
- CT/MRI