Exam 4: Pituitary Disorders Flashcards
What does ACTH do?
Stimulates production and release of cortisol by the adrenal cortex
What does LH do in females?
Triggers ovulation and development of the corpus luteum
What does LH do in males?
Stimulates Leydig cell production of testosterone
What does FSH do in females?
Stimulates growth of ovarian follicles
What does FSH do in males?
Stimulates formation of secondary spermatocytes
What does GH do?
Stimulates growth, cell reproduction, and cell regeneration
What does prolactin do in males?
Works with LH and Testosterone to increase reproductive function
What two hormones does the posterior pituitary release?
ADH and oxytocin
What does ADH do?
Causes the kidneys to reabsorb solute free water, resulting in concentrated urine and reduced urine volume
What does oxytocin do?
- In a positive feedback loop, increases uterine contractions and promotes stretching of the cervix and uterus during labor
- in breastfeeding women, it also stimulates the contraction of cells around the milk ducts causing milk to be released
What does the intermediate pituitary do?
Synthesizes and secretes melanocytes stimulating hormone, which controls skin pigmentation
Which part of the pituitary does no synthesize hormones, but just holds and secretes them?
The posterior pituitary does not synthesize any hormones
What is the most common place to get a sellar mass?
The sella Turcica
What is the clinical presentation of a sellar mass?
Visual impairment, diplopia, and headaches
Why do visual disturbances commonly happen with sellar masses?
Occurs as a result of suprasellar extension of the adenoma, leading to compression of the optic chiasm
-Commonly causes bitemporal hemianopsia
Are pituitary adenomas, craniopharyngioma, and meningioma usually benign or malignant?
Benign
What cancers are most likely to metastasize to the brain?
Breast and lung cancer
What accounts for over 60% of all pituitary adenomas?
Prolactinoma
What constitutes as a microadenoma?
Macro adenoma?
Micro: <1cm
Macro: >1cm
How are sellar masses diagnosed?
- MRI
- check labs for hormonal hypersecretion (serum prolactin, serum IGF, 24 hours urine cortisol, and T3/T4/TSH
What results from GH excess?
Gigantism and acromegaly
What results from GH deficiency?
Short stature, adult deficiency
What are the clinical features of a prolactinoma in premenopausal women?
- Infertility
- Amenorrhea
- Galactorrhea
What are the clinical features of prolactinoma in postmenopausal women?
- Headache
- impaired vision
- Galactorrhea
What is the clinical presentation of prolactinoma in men?
Decreased libido, impotence, infertility, gynecomastia, and galactorrhea
How is a prolactinoma diagnosed in premenopausal women?
Serum prolactin >30ng/mL
How is a prolactinoma diagnosed in postmenopausal women and men?
Serum prolactin >20ng/mL
What are the possible causes of hyperprolactinemia?
Pregnancy, lactation, stress, exercise, drugs (phenothiazine, haloperidol, and benzos), or pathologic (prolactinoma and hypothyroid)
How is a prolactinoma treated?
Pharmacologic: Bromocriptine, cabergoline
Surgical: transsphenoidal resection, radiotherapy
What is the most common etiology of growth hormone excess?
Benign pituitary macroadenoma
Increase in GH causes an increase in ** from the liver.
Insulin like growth factor (IGF-1)
What are the clinical features of GH excess?
- occurs in adults, enlargement/elongation of hands, feet, and jaw
- increased risk of DM, HTN, and CAD
How is growth hormone excess diagnosed?
- serum IGF
- serum prolactin
- 2 hour oral glucose tolerance test
- MRI will reveal pituitary tumor in 95% of patients
What is the gold standard to diagnose GH excess and what will it show?
-2 hour oral glucose tolerance test, will show failure of GH to decrease to less than 2mcg
*** random serum GH is not accurate as levels fluctuate
How is GH excess treated?
- somatostatin analogs are inhibitory and may decrease tumor size
- transsphenoidal microsurgery is most successful in patients with GH levels below 50 and pituitary tumors <2cm
- IGF should be measured every 3-6 months, as this is directly linked to morbidity and mortality
Is gigantism or acromegaly more common in adults?
Acromegaly
What is the most common etiology of GH deficiency?
Pituitary adenoma
What is the rare etiology of GH deficiency?
Sheehan syndrome
What are the clinical features of GH deficiency?
Decrease in lean body mass, decrease in bone mineral density, decrease in QOL, increase in fat mass, increase in rate of fractures, increase in mortality
What is the #1 cause of GH deficiency in adults?
Tumors
What is the recommended therapy for GH deficiency in patients who have childhood onset of GH deficiency?
GH therapy
What are the side effects of supplemental GH therapy?
Peripheral edema, arthralgia, paresthesias, and worsening of glucose tolerance
What is the difference between primary and secondary hypogonadism?
Primary: due to failure of the testes
Secondary: due to defects in the HPT axis
What will labs show in primary hypogonadism?
Low testosterone, high FSH and LH
What will labs show in secondary hypogonadism?
Low testosterone, low to normal FSH and LH
What are the clinical features of secondary hypogonadism?
ED, hot flashes, gynecomastia, infertility, decreased energy, libido, muscle mass, and body hair
How is secondary hypogonadism diagnosed?
Free and total serum testosterone, LH, and FSH
- prolactin, TSH, CBC, CMP, possibly semen analysis
- MRI
What are the testosterone treatment options for secondary hypogonadism?
- IM injections Q 2 weeks
- Transdermal cream/gel/patch applied daily
- pellets placed SC Q3 months
Before initiating treatment for secondary hypogonadism, what should be done?
-DRE and PSA as history of prostate cancer is contraindicated in testosterone therapy
What should be done to monitor treatment for secondary hypogonadism?
-Free and total testosterone, CBC (risk of erythrocytosis, free estradiol, and annual DRE and PSA
What is it called when a patient has global anterior pituitary dysfunction, resulting in decreased anterior pituitary hormones?
Pan hypopituitarism
What are the etiologies of Pan-hypopituitarism?
Radiation therapy, pituitary tumors, Sheehan syndrome, and extrapituitary syndrome
What is Sheehan syndrome?
Postpartum pituitary gland necrosis, due to blood loss and hypovolemia shock during and after childbirth
What is the most common initial symptom of Sheehan syndrome?
Agalactorrhea/ difficulties with lactation
How is pan-hypopituitarism diagnosed?
Extensive history and physical exam, full hormone work up, brain MRI, and stimulation tests as indicated to exclude primary disease
What is the treatment for pan-hypopituitarism?
- Extensive hormone replacement for life (Levothyroxine, dexamethasone, testosterone, estrogen-progestin, and GH)
- 1500 mg Ca with 800 IU of Vit D per day to protect the bones
What are the two disorders of the posterior pituitary?
Central DI, and SIADH
What is it called when there is decreased release of ADH from the posterior pituitary?
Central DI
What are the common etiologies of central DI?
- Most are idiopathic
- second most common is tumor of the posterior pituitary
What is the clinical presentation of Central DI?
- Overly dilute urine and polyuria
- dehydration
- polydipsia
- ice water craving
- nocturnal/enuresis
- hypernatremia in late stages
How is central DI diagnosed?
- 24 hour urine collection
- serum electrolytes
- simultaneous serum and urine osmolality
- glucose
What will the urine osmolality be in central DI?
<250 mOsm/kg
What is the treatment for central DI?
-Desmopressin (available intranasal)
What is it called when there is inappropriately high release of ADH from the posterior pituitary?
SIADH
What is the clinical presentation of SIADH?
- Overly concentrated urine and decreased urine volume
- increase urine osmolality
- decreased serum osmolality
- hyponatremia
How is SIADH diagnosed?
- 24 hour urine collection
- serum electrolytes
- simultaneous serum and urine osmolality
What is the treatment for SIADH?
- focused on correcting the hyponatremia
- fluid restriction to <800mL/day
- consider oral salt intake
- consider vasopressin receptor antagonist
