Endocrine HTN

Question 1

Pressor vs volume overload type HTN

Answer 1

• Pressor: result of circulating vasoconstriction agents, such as elevated RAS and catecholamines (seen in pheochromocytoma)
• Volume overload: abnormality of Na and H2O regulation (seen in 1o hyperaldosteronism and low renin HTN)

Question 2

Activation of RAS

Answer 2

• Increased renal BP leads to increased stretch of arterioles and decreased renin release
• MD cells notice a drop in Na delivery to TAL and increase renin release
• ATII: causes vasoconstriction, release of aldosterone from zone glomerulosa of the adrenals
• Aldo: promotes Na (and H2O) reabsorption and K secretion

Question 3

Na state of pts w/ hyperaldosteronism

Answer 3

• These pts are eunatremic for a number of reasons:
• Increased intravascular volume due to water retention
• ANP released due to stretch of the atria, which causes Na dumping
• Pressure natriuresis causing Na dumping
• Overall: normal serum Na
• However, the pts are hypokalemic and alkalotic

Question 4

1o vs 2o hyperaldosteronism

Answer 4

• Both cause hypokalemia and alkalosis, HTN
• In 1o hyperaldo the renin levels will be LOW to try and compensate
• In 2o hyperaldo the renin levels will be HIGH b/c that is whats leading to the hyperaldo
• Causes of 1o: aldo producing adenoma, primary adrenal hyperplasia (most common), adrenocortico CA
• Causes of 2o: renal artery stenosis, renin-secreting tumor, CKD, malignant HTN

Question 5

Pheochromocytoma

Answer 5

• Rare tumors that cause pressor type HTN by releasing large amounts of catecholamies
• Tumors usually develop in adrenal medulla, they produce NE and/or epi
• Can be Dx w/ 24 hr urine and looking at metanephrine and nor-metanephrine levels (break down products), which must be >2-3x ULN

Question 6

Sx of pheochromocytoma

Answer 6

• HTN (may be severe) w/ paroxysms of severe HTN + pallor, headache, flushing, sweating, palpitations, hyperglycemia
• These paroxysms last less than 15 min
• Pheo tumors may be sporadic or associated w/ MEN II syndromes
• Epidemiology: ages 30-50, usually solitary (if bilateral think familial/MEN)

Question 7

Rx of pheochromocytoma

Answer 7

• Surgical removal of the tumor after medical therapy

- First alpha blockade, then beta blockade, then surgery

Question 8

When to consider excess aldo for a pt

Answer 8

• Any individual w/ HTN + hypokalemia

- Any individual on the extremes of age w/ HTN

Question 9

Differentiating primary adrenal hyperplasia vs aldo-producing adenoma

Answer 9

• Look at 18-OHcorticosterone (18OHB, precursor to aldo) levels, if above 50 its an adenoma, if less than 50 its primary adrenal hyperplasia
• Can also do posture test (blood test when supine and then standing after 30 min of supine)
• If the 18OHB levels are stable then its adenoma, if the 18OHB levels rise its adrenal hyperplasia

Question 10

MEN type II

Answer 10

• Both are associated w/ RET oncogenesis, causes constitutively active tyrosine kinase
• Both are associated w/ pheochromocytoma (and medullary thyroid CA), familial, and bilateral
• MEN IIA (codon 634 of RET): pheochromocytoma, medullary thyroid CA, hyperparathyroidism
• MEN IIB (codon 918 of RET): pheochromocytoma, medullary thyroid CA, neurofibromas