Endocrine disorders 1 Flashcards
What hormones are released by the posterior pituitary (2)
antidiuretic hormone and oxytocin
role of ADH (1)
enhances water reabsroption from the collecting ducts
role of oxytocin (2)
controls ejection of milkk from lactating breast and initiates uterine contractions
What stimulates growth hormone secretion (4)
- stress, hypogylcemia
- glucagon
- some aa, e.g. arginine
- drugs such as levodopa and clonidine
secretion of GH releasing hormone, and therefore of GH is pulsatile, occuring about 7-8x a day, and is usually associated with… (3)
- exercise
- onset of deep sleep
- in response to the falling plasma glucose about an hour after meals
Action of GH is primarly mediated by ____.
IGFs
Effect of GH on:
a. carbohydrate metabolism
b. fat metabolism
c. protein synth
Effect of GH on:
a. carbohydrate metabolism = GH antagonies the insulin-mediated cell uptake of glucose, and excess secretion may produce glucose intolerance
b. fat metabolism = lipolysis is stimulated, with a consequent increase in the concentration of circulating free fatty acids that will antagonizes insulin release and action
c. protein synth = GH stimulates aa uptake by cells.
Besides enlarged hands, feet, jaw, heart… people with increased GH have predisposition to ____ and ____ and these lab findings (3) are increased
predisposition to multiple pre-malignant colon polyposis and hypertension.
Hyperphosphatemia, hypercalcemia, hypertriglycerideamia
What test do we do if we suspect acromegaly?
glucose suppression test (OGTT)
Failure to suppress glucose can suggest acromegaly or gigantism, but also ___ (5)
- severe renal disease
- severe liver disease
- heroin addiction
- levodopa
- DM
What parameter do we use to monitor acromegaly or treatment for it?
IGF-1
What state (1) increases IGF-1, and what states (3) decrease it?
increase: pregnancy
decrease: DM, starvation, obesity
How do you treat GH disorder?
- surgery to remove adenoma
- bromocriptine (dopamine receptor agonist)
- or somatostatin analouge
What finding of GH do we expect in healthy individuals after glucose intake?
In healthy individuals, plasma GH concentration would be suppressed to less than 1 mg/L by the glucose intake.
Symotpms of GH deficiency: adults (3) and children (1)
adults: tiredness, CVD, dyslipidemia
children: short stature - birthweight can be normal, but rate growth subnormal
How will deficiency of ADH present (2)?
diabetes insipidus: polyuria
syndrome of inappropriate ADH: hyponatremia
List consequences of pituitary hormone deficiencies (4)
- growth retardation in children: low GH; low TSH and thyroid horm.
- secondary hypogonadism: low gonadotropin deficiency (amenorrhea, infertility, atrophy of secondary sexual characteristics, delayed puberty)
- secondary adrenocortical hypofunction (ACTH def)
What tests do we order for suspected hypopituitarism? (4)
Plasma concetrations of:
1. sex hormones: LH, FSH, estradiol (female) and testosterone (male)
2. thyroid: total or free T4 and TSH
3. prolactin (to test for hypothalamic or pituitary stalk involevemnt)
4. cortisol at 9am to assess the risk of adrenocortical insufficiency
Insulin test stimulation indications (3)
- assess GH in growth deficiency
- assess ACTH/cortisol reserve
- differentiation of Cushingßs syndrome vs pseudoCushingßs syndrome
Insulin test stimulation contraindications (5)
- elderly
- ischemic heart disease
- epilepsy
- pts who have cortisol < 100nmol/L at 9am
- severe panhypopituitarism
How do we differentiate Cushings syndrome vs pseudoCushing
In Cushing’s syndrome, neither plasma cortisol nor GH concentrations rise significantly after insulin stimulation test, although they usually do in cases of pseudo-Cushing’s syndrome
What test do we do if insulin hypoglycemic test is contraindicated?
glucagon stimulation test of the hypothalamus-pituitary axis
