Endocrine Hypertension Flashcards
What is the definition of hypertension?
Systolic BP: >140, Diastolic >90
In two or more visits after the initial screen
At what age do we stop using 95% percentile as the definition of hypertension in children? What is this definition?
Children aged 13+
> 130 systolic or >80 diastolic is HTN
What is primary vs secondary hypertension and what are the three endocrine causes of hypertension?
Primary - 85%, also known as essential hypertension, no known etiology
Secondary - 15%
- Renovascular hypertension
- Pheochromocytoma
- Primary aldosteronism
What are presentations of hypertension which make you lean more towards an endocrine cause than primary / essential hypertension?
- Severe / resistant HTN (refractory after 3+ meds)
- Young onset (<30), or rapid old onset
- Hypertension with spontaenous hypokalemia (hyperaldosteronism)
- Episodic HTN - pheochromocytoma
- Characteristic physical exam findings
What are characteristic physical exam findings for primary aldosteronism causing hypertension?
Often due to hypokalemia, there are characteristic physical exam findings:
- Neuromuscular irritability
- Muscular weakness (inability to increase blood flow to muscles)
What physical exam findings are associated with pheochromocytoma?
- Cold, clammy hands - peripheral vasoconstriction
2. Cafe au lait spots - if associated with NF-1
What physical exam finding is associated with renovascular hypertension?
Abdominal bruit -> if HTN is caused by renal artery stenosis
What is the most common cause of secondary hypertension? What is the threshold at which this occurs and what are the two subtypes?
Renal artery stenosis
-> occurs at greater than 75% stenosis
- Atherosclerotic - usually elderly patients, 2/3
- Fibromuscular dysplasia - usually young women, 1/3
What are the two types of fibromuscular dysplasia and which is more common? Where in the renal artery does this occur?
- Medial fibroplasia -> much more common (80%)
- Intimal fibroplasia
Occurs usually in distal renal arteries -> string of beads appearance
When will renin be high vs not in renovascular hypertension?
Unilateral - can be high or normal, as contralateral kidney will decrease renin production -> choose to treat via clinical index of suspicion
Bilateral - will be high, along with increased BUN / creatinine
What is the gold standard of renovascular hypertension diagnosis and what is done to treat? Is it effective?
Gold standard: Renal angiography
- > treat with angioplasty with stent placement
- > very effective in fibromuscular dysplasia, moderately effective in atherosclerosis (restonosis occurs)
Where in the renal artery is fibromuscular dysplasia vs atherosclerotic stenosis?
Fibromuscular dysplasia - distal renal artery segments
Atherosclerotic disease - proximal segments (near branch points from aorta)
What is the medical therapy for renovascular hypertension?
ACE inhibitors (except in bilateral renal artery stenosis)
or
ARBs (i.e. valsartan)
mainstay due to pathogenic mechanism
When is surgery preferred over medical therapy for renovascular HTN?
Recent onset HTN (<5 years), particularly younger patients
Intolerant to medical therapy
Recurrent flash pulmonary edema or refractory heart failure
Is hypokalemia required for primary aldosteronism? What can precipitate it?
No! In fact, most patients are not hypokalemic because of the body’s potassium conservation mechanism
Diuretics can precipitate it however -> diuretic-induced hypokalemia is a common way of diagnosing
Does primary aldosteronism present with peripheral edema? How?
No -> aldosterone escape mechanism.
Spontaneous diuresis occurs to excrete sodium to normal levels and limit expansion of extracellular volume by release of atrial natriuretic peptide (ANP) -> released in response to distention
What is typically used as the screening test for primary aldosteronism?
PAC/PRA ratio
Plasma aldosterone concentration / plasma renin activity
If ratio >20, it has 100% sensitivity, because aldosterone will be very high compared to renin.
How is definitive diagnosis of primary aldosteronism made? What should be done if this test is positive?
Salt-loading. Salt load for 3 days
-> urinary sodium will be high, but aldosterone will be non-suppressed.
If test is positive -> order CT scan of adrenal to look for abnormality
What should be done for patients with a normal adrenal CT following a positive test for primary aldosteronism? How about if you are over age 40 and CT is positive?
Same test for both: adrenal vein aldosterone sampling -> see which adrenal gland is overproducing.
Over age 40, non-functioning adenomas are common -> need to sample adrenal vein to be sure gland is overproducing
What drugs are used for medical treatment of primary aldosteronism and which is preferred?
Spironolactone and Eplerenone
Spironolactone is preferred -> longer halflife and greater antagonist activity
Eplerenone - fewer anti-androgen side effects, but more expensive
What is the classic triad of pheochromocytoma?
Headache
Sweating
Palpitations
Does pheochromocytoma always present with hypertension? What is the patternof HTN?
95% of people will have hypertension
50% will have intermittent (episodic) HTN, but 50% have sustained HTN as well.
5% of people remain normotensive due to adrenoceptor downregulation.
What defines a low vs high risk patient for pheochromocytoma?
Low - resistant HTN with hyperadrenergic spells, and adrenal mass w/o characteristics of pheo
High - Previously resect pheo, FHx of pheo, genetic syndrome related to pheo (i.e. MEN2), adrenal mass with high suspicion on MRI/CT
What testing should be done for pheochromocytoma in low and high risk patients? Which one should children have done?
Low risk - Urinary fractional metanephrines -> higher specificity, lower sensitivity (i.e. patients with minimal acute symptoms unlikely to have major problems)
High risk - Plasma fractional metanephrines -> higher sensitivity for when it matters, but lower specificity (many false positives)
Children -> do plasma metanephrines since much easier
What is the imaging study of choice for pheochromocytoma?
MRI - increased brightness on T2 MRI, best overall test
CT - can be used, but high rate of misdiagnosis of incidentaloma
MIBG radionucleotide scan -> used only for extra-adrenal localization
What is the treatment sequence for pheochromocytoma?
- Alpha blockade - irreversible, i.e. phenoxybenzamine
followed by:
- Beta blockade
- > reversing this order could cause hypertensive crisis
then
- Tumor resection
When should germline screening for pheochromocytoma be done?
Young age
Bilateral pheos
Unilateral pheo with FHx
Paraganglioma present
What germ lie mutations are associated with pheochromocytoma?
NF-1 -> neurofibromatosis 1
VHL -> von Hippel Lindau
RET -> MEN2A and 2B
What is pseudopheochromocytoma, and what must be ruled out?
Disease of paroxysmal hypertension caused by increased sympathetic tone
Rule out:
Labile HTN
Panic Disorder
