Endo: Pit Dysf (PRL, GH, Adrenal) Flashcards
Compare central and peripheral hormone disorders.
Central: problem is in hypothalamus or pituitary gland
Peripheral: problem is in end organ (eg. adrenal, ovaries, etc)
What is a Rathke’s cleft cyst?
What are the symptoms?
- Rathke’s cleft cyst is a remnant of Rathke’s pouch
- Asymptomatic
Is craniopharyngioma malignant or benign?
Craniopharyngiomas are benign, slow-growing tumors (Grade I)
Describe the type of craniopharyngioma most common in children.
(Name, CT feature, 3 sx)
- Adamantinomatous
- Calcifications on CT
- Sx: growth failure, delayed puberty, tunnel vision
An adult walks in with headache, vision changes, and hypopituitary function.
What is one possible neoplasm?
- Papillary craniopharyngioma
Are pituitary adenomas usually sporadic or inherited?
Do they always produce hormones?
Pituitary adenomas are usually sporadic.
They may or may not produce hormones
A patient presents with headaches, bitemporal hemianopsia, opthalmoplegia, and pituitary hormone deficits.
Why are these symptoms occuring?
- Pt has a pituitary tumor
- Headache, visual field deficits, and cranial nerve palsies are due to mass effect (tumor pressing on other structures)
What is the order in which pituitary hormones will decrease with a pituitary adenoma?
Gonna - GH
Lose - LH/FSH
The - TSH
Anterior - ACTH
Pituitary - PRL
(or, “go look for the adenoma please”)
Describe the HPA axis for growth hormone (4)
- Hypothalamus releases GHRH
- GHRH stimulates GH release by anterior pituitary somatotrophs
- GH stimulates liver to release IGF-1
*Hypothalamus can also release Somatostatin, which inhibits anterior pituitary release of GH
What is the effect of glucose on GH release?
Effect of sleep?
Effect of exercise?
Effect of puberty?
- Glucose suppresses GH release
- Sleep, exercise, and puberty all increase GH release
Name 2 effects of IGF-1
- Increased muscle growth
- Increased bone growth
Compare the onset and signs of gigantism and acromegaly
- Gigantism: GH excess before puberty
- Tall
- Acromegaly: GH excess after puberty
- Increased hand, feet, head size
How do you diagnose GH excess?
Why do we use this method?
- Increased IGF-1 level
- Don’t measure GH directly b/c GH has a short half-life and is released in pulsatile waves, so difficult to get a representative measurement
What is the medical treatment of acromegaly and gigantism?
Octreotide (somatostatin analog)
What are the symptoms of GH deficiency in adults? (4)
Is this always pathalogic?
GH deficiency causes
- Increased fat
- Decreased muscle
- Decreased bone density, fractures
- Increased cholesterol
*All occur with normal aging, too
What is the treatment of GH deficiency in adults?
GH can be administered, but its use is controversial
How do you diagnose GH deficiency? (2)
- Low IGF-1
- Induce hypoglycemia with insulin and see if GH rises (it should)
What hormone released by the hypothalamus stimulates PRL release from ant pituitary?
Thyroid releasing hormone (TRH)
A woman presents with galactorrhea, menstrual irregularity, and infertility.
What tumor could cause this?
These are all symptoms of prolactinoma.
A male presents with visual field abnormalities, headache, opthalmoplegia, and impotence.
What tumor could cause this?
Prolactinoma
Men tend to have large tumors, so sx largely due to mass effects
Bromocriptine: MOA, use
- MOA: Dopamine agonist
-
Use: Tx for prolactinoma
- Cabergoline is first line, but bromocriptine is better if going to become pregnant
What agent is first line in treatment of prolactinoma?
Cabergoline, a dopamine agonist
What are the symptoms of PRL deficiency in men and women? (1 each)
- Women: failed lactation after childbirth
- Men: no known effects
What are the effects of cortisol?
A BIG FIB
- Appetite increased
- Blood pressure increased
- Insulin resistance
- Gluconeogenesis and lipolysis increased
- Fibroblast suppression
- Inflammation suppression
- Bone formation decreased
Symptoms of cortisol excess (Cushing’s)
- Body habitus (4)
- Skin (1)
- Bones (1)
- Metabolism (2)
- CV (1)
- Immune (1)
- Reproductive (2)
- Body habitus: peripheral wasting, central obesity, buffalo hump, proximal muscle weakness
- Skin: violet striae
- Bones: osteoporosis
- Metabolism: diabetes, hyperTGemia
- CV: HTN
- Immune: immunosuppression
- Reproductive: amenorrhea, hirsutism
- Cortisol levels are highest in ______ (time)
- Cortisol levels are lowest ______ (time)
- Cortisol levels are highest in early morning
- Cortisol levels are lowest during sleep
Compare Cushing’s disease and Cushing’s syndrome
Cushing’s disease is a ACTH-secreting pituitary adenoma
Cushing’s syndrome is elevated cortisol for any reason
What are 3 screening tests for Cushing’s syndrome?
- Midnight salivary cortisol is elevated
- Increased free cortisol in urine
- Dexamethasone doesn’t suppress cortisol
Hypogonadism can be caused by either excess ____ or insufficient ____
Hypogonadism can be caused by either excess PRL or insufficient FSH/LH
Compare primary, secondary, and tertiary HPA disorders
Primary: problem is in end organ
Secondary: problem is in pituitary
Tertiary: problem is in hypothalamus
What is the origin of craniopharyngiomas?
Derived from ectopic Rathke’s pouch remnant
What is another name for growth hormone?
What is another name for IGF-1?
GH = somatotropin
IGF-1 = somatomedin
*Somatotatin inhibits GH’s release
Describe the HPA axis for Prolactin
- Hypothalamus releases TRH
- TRH stimulates lactotrophs in anterior pituitary to release prolactin
- Prolactin causes lactation and mammary gland growth
*Dopamine inhibits Prolactin release from anterior pituitary
How do you diagnose prolactinomas?
Random PRL level
Effects of prolactin (2)
- Stimulates milk production and mammary gland growth
- Suppresses GnRH release, preventing ovulation/spermatogenesis
Describe the HPA axis for cortisol
- Hypothalamus secretes CRH
- CRH stimulates anterior pituitary to release ACTH
- Adrenal secretes cortisol
A patient has symptoms of Cushing’s syndromes and a low ACTH.
What does this tell you?
Low ACTH means that the excess cortisol secretion is not being driven by pituitary dysfunction.
What is central adrenal insufficiency?
What is the most common cause?
- Central adrenal insufficiency is low CRH or ACTH release (pituitary or hypothalamus dysfunction)
- Usually due to glucocorticoid use (drug-induced)
A patient presents with fatigue, anorexia, weight-loss, scant axillary & pubic hair, sugar/salt craving.
Diagnosis?
Adrenal insufficiency
How do you diagnose adrenal insufficiency?
- Measure random cortisol level
- Induce hypoglycemia with insulin, and see if cortisol rises (it should)
