Endocrine Flashcards
First test in work-up of suspected acromegaly?
Second test if positive?
First test: IGF-1 level
Follow-up if positive: Oral glucose suppression test for GH (will fail to suppress in acromegaly)
Most common primary pituitary tumor?
Prolactinoma
When do prolactinomas require treatment?
What is the treatment?
Symptomatic or >1 cm in size
Treatment: DA agonists (e.g. cabergoline, bromocriptine) if <3 cm, larger goes to surgery
HPG axis hormone levels in Klinefelter syndrome?
Testosterone: low
FSH/LH: elevated (lack of negative feedback from testosterone)
Kallman syndrome
Hypogonadotropic hypogonadism (pubertal failure) + anosmia
Migration defect in GnRH-secreting and olfactory neurons
Key difference between primary and secondary adrenal insufficiency?
Primary: loss of glucocorticoid and mineralocorticoids, +hyperpigmentation (ACTH stimulating MSH receptors)
Secondary: loss of glucocorticoids only (mineralocorticoids regulated by RAAS, not ACTH)
Menstrual irregularity in PCOS? Cause?
Long, irregular periods.
Excess androgen converted to estrogen, prolonging the proliferative phase.
Potential cause of rapid-onset hirsuitism +/- virilization in women?
Test?
Androgen-secreting neoplasm
Test: serum testosterone and DHEAS (dehydroeplandrosterone, produced by adrenal neoplasm and converted to testosterone peripherally)
Who should get surgery for primary hyperparathyroidism?
- Symptomatic hypercalcemia
- Complications (osteoporosis, stones, renal dysfunction)
- High risk for complications (Ca2+ >1 mg/dl over normal, high urine calcium excretion, age under 50)
Tumors in MEN1? MEN2A? MEN2B?
MEN1: 3 P’s
- Primary hyperparathyroidism
- Pituitary tumors
- Pancreatic endocrine tumors (esp. gastrinomas)
MEN2A: 2 P’s, 1 M
- Pheochromocytoma
- Primary hyperparathyroidism
- Medullary thyroid cancer
MEN2B: 1 P, 3 M’s
- Pheochromocytoma
- Medullary thyroid cancer
- Mucosal neuroma
- Marfanoid habitus
Pheochromocytoma and thryoid storm can both lead to dangerous hypertension during surgery. What is a key difference?
Thyroid storm will have fever, pheo will not
Initial medical treatment for pheochromocytoma
Alpha blocker followed by beta blocker
Need to make sure alpha is block first so don’t see unopposed alpha vasoconstriction with beta block
Most common cause of primary adrenal insufficiency?
Autoimmune adrenalitis
Initial treatment of hyperosmolar hyperglycemic state
- Aggressive hydration with NS (regardless of sodium, due to fluid deficit due to polyuria, can give 1/2 NS later)
- IV insulin + potassium
Correction for sodium in hyperglycemia
Add 2 mEq/L Na+ for every 100 mg/dl glucose is above 100
Sign of glucagonoma on exam
Necrolytic migratory erythema: erythematous papules/plaques on face, limbs, and perineum, that enlarge/coalesce over 2 weeks, then develop central clearing and blistering with crust and scale
Cause of “bronze diabetes”
Hereditary hemochromatosis (iron deposition in skin and pancreas, also deposits in liver and other organs)
Major cause of death in hereditary hemochromatosis
Cirrhosis and Hepatocellular carcinoma (20x general population)
Oral antihyperglycemics with highest risk of hypoglycemia?
Sulfonylureas (e.g. glipizide, gliclazide, or glimepiride)
Oral antihyperglycemics that can help with weight loss?
GLP-1 agonists (e.g. exenatide)
Oral antihyperglycemics that can lead to heart failure?
Thiazolidenidiones (e.g. pioglitazone)
Initial tests in a thyroid nodule
TSH and ultrasound
Treatment for thyroid storm
- Propanolol
- Thionamides (e.g. propylthiouracil, PTU)
- Iodine (blocks thyroid hormone delease, delay 1 hour after PTU)
- Glucocorticoids (decrease T4 -> T3 conversion)
Calcium disturbances in thyroid disease
Hyperthyroidism activates osteoclasts (bone loss), bone resorption frees calcium, excess calcium excreted in urine (hypercalciuria, stones).
Serum calcium usually normal due to renal excretion and decreased vitamin D activation.
Blood pressure in thyroid disease
Hyperthyroid: systolic HTN due to increase cardiac output
Hypothyroid: diastolic hypertension due to increased resistance and renal dysfunction
Rare but serious reaction to thionamides (PTU, MMI)
Agranulocytosis
(If patient on these drugs comes in with fever and sore throat, immediately stop drug and get a WBC count to check for agranulocytosis)
Most common form of thyroid cancer?
Papillary thyroid cancer
Pathologic findings in papillary thyroid cancer on FNA
Psammoma bodies: grainy, lamellated calcifications
P for Papillary and Psammoma
More aggressive but still common thyroid cancer?
Follicular thyroid cancer (2nd most common, more invasive, can metastasize)
Pathologic findings in follicular thyroid cancer on FNA
Indistinguishable from follicular adenoma (many follicular cells in clusters and microfollicles).
Need excisional biopsy of entire nodule to diagnose (invasion in cancer, not in adenoma)
Thyroid cancer that secretes calcitonin?
Medullary thyroid cancer (of parafollicular C cells)
Additional tests needed in patient with medullary thyroid cancer?
Plasma fractionated metanephrine assay for pheo.
MEN2 testing (RET proto-oncogene)
Effect of high titers of anti-TPO antibodies independent of whether patient is euthyroid or hypothyroid?
Increased risk of miscarriage
Diagnostic tests for adrenal insufficiency
A.m. cortisol, ACTH level, ACTH/cosyntropin stimulation test
Normal TSH and T4 but low T3 in a critically ill patient
“Euthyroid sick syndrome” or “low T3 syndrome” - due to decreased conversion of T4 to T3 in a sick patient
What fibers are damaged in diabetic neuropathy to cause different symptoms?
Small fiber axonopathy causes positive symptoms: pain and paresthesias
Large fiber axonopathy causes negative symptoms: numbness, loss of proprioception, hyporeflexia
Levels of DHEAS, LH, and T in:
Androgen-producing adrenal neoplasms?
Androgen-producing ovarian neoplasms?
Adrenal: elevated DHEAS and T, decreased LH
Ovarian: normal DHEAS, elevated T, decreased LH
