Endo E2- Pituitary

What is the central core of the forebrain?

Diencephalon

What are the three paired structures that make up the diencephalon?

Thalamus, hypothalamus, epithalamus

What does the diencephalon enclose?

Third ventricle

What does an empty sella indicate?

no pituitary gland

What tropic hormone is affected by CRH?

ACTH

What tropic hormone is affected by TRH?

TSH

What tropic hormones are affected by GnRH and GnIH?

LH & FSH

What tropic hormone is affected by somatocrinin & somatostatin?

GH

What hormone stimulates the release of growth hormone?

GH releasing hormone (from hypothalamus)

What are the target organs of GH?

Liver, adipose, bone, muscle

What are the effects of GH?

promotes growth & metabolism of lipids and carbs

What is the effect of hyposecretion of GH in children?

Pituitary dwarfism

What is the effect of hypersecretion of GH in children?

gigantism

What is the effect of hypersecretion in adults?

acromegaly

What hormone stimulates the release of TSH?

Thyrotropin-releasing hormone (TRH)

What is the effect of TSH on the thyroid?

Secretion of T4 & T3

T/F: T4 is converted to T3

True

Where is calcitonin produced?

parafollicular cells (C-cells) of the thyroid

What does calcitonin do?

reduce blood calcium, opposing the effects of PTH

(stimulates Ca uptake/incorporation into bone matrix)

What is increases calcitonin release?

hypercalcemia

What is the prolactin inhibiting hormone?

Dopamine

What is the effect of prolactin?

Milk secretion from breast

What stimulates the release of prolactin?

decrease in PIH

What hormone stimulates the release of ACTH?

Corticotropin releasing hormone (CRH)

What is the target organ of ACTH?

Adrenal glands

What is the effect of ACTH on the adrenal glands?

Secrete glucocorticoids/cortisol (from Zona fasciculata)

What part of the adrenal glands contain nervous tissues and is part of the sympathetic NS?

Adrenal medulla

What part of the adrenal glands is made up of 3 layers of glandular tissue that synthesize and secrete corticosteroids?

Adrenal cortex

What zone of the adrenal cortex secretes mineralocorticoids (aldosterone)?

Zona glomerulosa

What zone of the adrenal cortex secretes glucocorticoids (cortisol)?

Zona fasciculata

What zone of the adrenal cortex secretes adrenal androgens (DHEA)?

Zona reticularis

What does the adrenal medulla secrete?

catecholamines

What is the most potent mineralocorticoid?

Aldosterone

What is the action of aldosterone?

Na resorption and water retention by kidneys

What type of cells in the adrenal medulla secrete epi and NE?

Chromaffin cells

What are the actions of Epi and NE?

inc BG, blood vessels constrict, inc HR, blood diverts to brain, heart, and skeletal muscle

What hormone stimulates the release of FSH and LH?

GnRH

What is the effect of FSH on testes?

Inhibin secretion

What is the effect of FSH on ovaries?

Estrogen secretion

What is the effect of LH on testes?

Testosterone secretion

What is the effect of LH on ovaries?

Progesterone & Inhibin secretion

What does Melanocyte stimulating hormone do?

regulate synthesis of melanin in specialized cells and influences changes in skin pigmentation

What are some conditions that would cause an increase in melanocyte stimulating hormone?

Pregnancy, DM, Cushing's, Addisons

What is the precursor to ACTH and MSH?

POMC

What hormone has a positive feedback loop?

Oxytocin

What are the target organs of oxytocin?

Uterus, breast, prostate

What is the effect of oxytocin on the breasts?

Milk letdown

What is the effect of oxytocin on the prostate & uterus?

Smooth muscle contractions

What stimulates the release of ADH?

Na+ levels in blood

What is the effect of ADH?

Stimulates water retention & raises BP (arteriole contraction)

What happens to the collecting ducts in the absence of ADH?

become virtually impermeable to water, so it flows out as urine

What is the effect of too much ADH?

more concentrated urine & less concentrated blood plasma

What can be used as a medication to treat low BP?

Vasopressin (ADH)

What is the MC disease related to ADH?

diabetes insipidus

What is the most important variable regulating ADH secretion?

Plasma osmolarity

(Increase/decreased) BP would stimulate ADH secretion

Decreased

There is a parallel between ADH secretion and what?

thirst

FSH is higher in (premenopausal/postmenopausal) females

Postmenopausal

What are disorders of the ant. pituitary?

pituitary adenoma, hypopituitarism, GH deficiency, acromegaly, giantism, Cushing’s, Nelson’s

What are disorders of the post. pituitary?

DI, SIADH, Sheehan syndrome

What is a microadenoma?

pituitary adenoma < 10 mm

What is a macroadenoma?

pituitary adenoma > 10 mm

What type of pituitary adenoma secretes FSH/LH?

Gonadotroph

What type of pituitary adenoma secrete GH?

somatotroph

What type of visual symptom may be seen in a person with a pituitary adenoma?

Bitemporal hemianopsia

What sx might be present in a female patient with hyperprolactinemia?

Oligo/amenorrhea, galactorrhea, infertility, cardiomyopathy

What sx might be present in a male patient with hyperprolactinemia?

Hypogonadism, decreased libido, ED, infertility, gynecomastia

What are physiologic causes of hyperprolactinemia?

Exercise, pregnancy, breast feeding/nipple stimulation (piercings), stress/trauma

What drugs could cause hyperprolactinemia?

Amphetamines, Cimetidine, Ranitidine, Estrogens, Opioids, Nicotine, Verapamil, Cocaine

What type of imaging is the best choice for diagnosis of hyperprolactinemia due to a pituitary adenoma?

MRI

Does serum PRL testing for hyperprolactinemia diagnosis require fasting?

Yes- fast & check in AM

What is the tx of choice for hyperprolactinemia?

Dopaminergic drug- Cabergoline or Bromocriptine

When is surgical resection necessary for tx of pituitary adenomas?

Medications not working, HA, visual field deficit, CSF leak

What procedure is performed for surgical resection of pituitary adenomas?

Transsphenoidal pituitary surgery

What is panhypopituitarism?

loss of all anterior pituitary hormones

What is pituitary insufficiency?

Decreased function of one, any, or all pituitary hormones

What is a congenital cause of anterior hypopituitarism?

Kallmann syndrome

What is Kallmann syndrome?

Delayed or absent puberty & lack of smell

What is the MC lesion/tumor to cause anterior hypopituitarism?

Pituitary adenoma

What electrolyte imbalances should be ruled out with labs when diagnosing anterior hypopituitarism?

Hyponatremia and hyperkalemia

What is the 1st line tx for anterior hypopituitarism?

Replace the hormone

Anterior (hypo/hyper) pituitarism patients should wear a medical alert necklace/bracelet

Hypopituitarism

What hormone inhibits GHRH?

Somatostatin

How does GH promote linear growth?

regulating production of Insulin-like growth factor 1 (IGF-1)

Why do adults with GH deficiency have a reduced life expectancy?

Premature CV disease

What is growth failure after a period of normal growth characteristic of?

GH deficiency

Adults with GH deficiency usually have hx of what?

Pituitary tumors treated with surgery/radiation OR head trauma

What is the #1 cause of dwarfism?

Achondroplasia

What is the standard test for diagnosis of GH deficiency in adults?

Insulin tolerance test (ITT)

When should adults with GH deficiency d/c GH therapy?

no benefits seen after 1 year of tx (continue as long as benefits are observed)

How is prognosis of GH deficiency determined?

Response to GH therapy

What is gigantism?

abnormally high linear growth due to excessive IGF-1 while epiphyseal growth plates are open during childhood

What is acromegaly?

abnormally high linear growth due to excessive IGF-1 while epiphyseal growth plates are fused during adulthood

Which is more common: acromegaly or gigantism?

Acromegaly

What are the most frequent causes of death in people with acromegaly & gigantism?

CV & respiratory complications

What is a cardinal clinical feature of gigantism?

Longitudinal acceleration of linear growth secondary to IGF-1 excess

What is the key pathologic factor in gigantism and acromegaly?

IGF-1

(Hyperthyroidism/Hypothyroidism) may be seen in patients with gigantism

Hypothyroidism

What is the criterion standard for diagnosing GH excess?

Inability to suppress serum GH level during an OGTT

*cannot get GH < 5 w/in 3 hrs of OG

What medications can be used to bind to pituitary dopamine type 2 receptors and suppress GH secretion in patients with GH excess?

Dopamine agonists (Bromocryptine or Cabergoline)