Ch 21: Parathyroids and Adrenals

Question 1

What is the most common cause of congenital adrenal hyperplasia and how will this manifest in females?

Answer 1

• Major cause: 21-hydroxylase (P450C21) deficiency
• manifests as pseudohermaphroditism in females (ambiguous genitalia but internal organs are normal)
• androgens and progesterone are increased, while glucocorticoids and mineralocorticoids are decreased (salt wasting, hypovolemia, hypotension)

Question 2

What are symptoms of hypocalcemia and what endocrine should you always check when you suspect hypocalcemia?

Answer 2

• symptoms: numbness, tingling, muscle spasms
• check PTH levels!
• damage to the PTH (primary) usually occurs via autoimmune damage, surgical excision of thyroid, or DiGeorge syndrome - serum PTH and calcium levels will be LOW
• if there is end organ resistance to PTH (pseudohypoPTH), usually due to a mutation in receptors that makes them unable to produce cAMP, the serum PTH will be high while calcium will be low

Question 3

Patient presents with several kidney stones. What workup would you want to do, and what are you suspecting?

Answer 3

• check calcium levels! High calcium and low phosphate can lead to deposition of stones
• also check PTH levels - with stones, we suspect hyperparathyroidism, which can be due to PTH adenoma, hyperplasia, or carcinoma
• look for other symptoms, such as depression, memory issues, nausea (increased gastric acid secretion), and osteitis fibrosa cystica

Question 4

High calcium, high PTH, and a mass with sheets of neoplastic chief cells in a rich capillary network?

Answer 4

• parathyroid adenoma (most common cause of hyperparathyroidism)
• can be associated with MEN1

Question 5

Describe the steps in which chronic renal failure (the most common cause) can lead to secondary hyperparathyroidism

Answer 5

1) renal insufficiency leads to decreased phosphate excretion
2) increased serum phosphate binds free calcium
3) decreased free calcium stimulates PTH release (all 4 glands - will see hyperplasia equally)

• labs will show increased PTH, decreased serum calcium, increased serum phosphate, and increased alkaline phosphatase
• secondary hyperparathyroidism can also be caused by vit D deficiency, malabsorption, Fanconi syndrome, and renal tubular acidosis
• take home points: check calcium and phosphate levels to distinguish between primary and secondary causes of PTH

Question 6

Differentiate between MEN1, MEN2a, MEN2b

Answer 6

MEN1: pituitary adenoma, primary hyperparathyroidism, and islet cell tumor of pancreas

MEN2a: medullary thyroid carcinoma, pheochromocytoma, primary hyperparathyroidism
MEN2b: same as 2a, but develops earlier and usually without PTH involvement

MEN2 syndromes associated with RET mutation

Question 7

Neuroblastomas are the most common extra cranial solid neoplasms of childhood. 1/3 of these are adrenal. Describe the pathogenesis and symptoms

Answer 7

• may occur with NF1, Beckwith-Wiedemann syndrome, and Hirschsprung disease
• amplification of N-myc occurs
• abdominal mass with small blue cells and Homer Wright rosettes
• since affects adrenal medulla, urinary excretion of catecholamines and metabolites are elevated

Question 8

What are the symptoms of Cushing syndrome? What should be the first question you ask your patient if you suspect this?

Answer 8

• emotional disturbance, moon facies, osteoporosis, upper truncal obesity, thin and wrinkled skin, amenorrhea, muscle weakness, pupura, skin ulcers
• all due to excess production of cortisol from zona fasciculata of adrenal cortex
• ask them about exogenous corticosteroids, which are the most common cause of Cushing syndrome

Question 9

What is Cushing disease? How can you test to diagnose this?

Answer 9

• Excess cortisol due to pituitary tumors that secrete ACTH
• use the dexamethasone suppression test: if you administer and cortisol levels go down, you know the source is the pituitary

Question 10

Describe primary chronic adrenal insufficiency (Addison disease)

Answer 10

• most commonly due to autoimmune destruction of adrenal glands
• weakness, weight loss, GI disturbances, hypotension, hyponatremia, hyperkalemia, hyperpigmentation

Question 11

Tumor of chromaffin cells of adrenal medulla

Answer 11

Pheochromocytoma:

• secretes catecholamines –> HTN resistant to therapy (headaches, blurry vision, tachycardia, sweating)
• increased serum metanephrines and urinary VMA
• associated with MEN2, von Hippel-Lindau, NF1