Secondary forms of hypertension

Lisa Cohen recently summarized rare "genetic" forms of hypertension including Liddle's syndrome and PHA type II (Gordon's syndrome).

I want to summarize other causes of "secondary" hypertension which are not inherited (at least not typically in a Mendelian transmission) and which are potentially "fixable".

These phenotypes are distinct from primary hypertension which affects the vast majority of our patients. Secondary forms of hypertension affect typically less then <5% of patients with hypertension.

In order to identify a reversible cause for hypertension following data needs to be obtained:

• HPI
• Family history
• Physical exam
• Initial labs including Chem7, Lipid panel, Urine analysis, EKG
• Indications for further labs include abnormal initial tests (high Ca++ levels, low K+ levels), abrupt onset of hypertension, young age (<30),>50), hypertension resistant or refractory to 3+ medications, worsening hypertension in a previously well controlled patient, BP >180/110 at onset.
  

The most common forms of secondary hypertension are:

1. Renovascular hypertension
2. Coarctation of aorta
3. Cushing’s syndrome
4. Primary Aldosteronism
5. Thyroid/parathyroid disease
6. Pheochromocytoma

Typically others causes such as CKD or sleep apnea are not considered "secondary" forms of hypertension. Physical and laboratory findings can help and guide in ruling out secondary forms of hypertension: If you find this -> think this !!!

1. Truncal obesity and striae -> Cushing's syndrome
2. Labile hypertension -> Pheochromocytoma
3. Abdominal bruits -> renovascular hypertension
4. Decreased BP and Pulse in lower extremities -> Coarctation of aorta
5. Abdominal flank masses -> Polycystic kidney disease
6. Elevated Crea and/or abnormal UA -> parenchymal kidney disease
7. Hypercalcemia -> Hyperparathyrodism
8. Hypokalemia -> Hyperaldosteronism (also Cushing's syndrome and Pheochromocytoma can present with this).

Last but not least, a few more facts on the three most common secondary forms of hypertension:

1. Renovascular hypertension- Renal artery artherosclerosis (males>50, Fibromuscular dysplasia (females<40),Other (rarer) causes include vasculitis, scleroderma, Takayasu arteritis, etc. - Labs show typically hypokalemia and hyper-reninemic hyperaldosteronism - Screening tests recommended are Doppler US, MRA, CT angio, captopril renogram - Gold standard is arteriography which could show “string of beads” vs. single stenosis
2. Hyperaldosteronism: Aldo causes increased Na+ uptake in distal tubule -> increase in intravascular volume
   -Suspect in patients with unexplained low K+
   -Main causes are adrenal adenomas (~ 70%) and b/l adrenal hyperplasia (~ 25%)
   -Screening by checking stimulated PRA or PRC which will be undectable or low
   -Confirm screening tests with salt/fluid loading -> "elevated" Aldo level will NOT be suppressed
3. Pheochromocytoma:
   -Rare tumors arising from chromaffin tissue of the adrenal gland
   -90% occur in the adrenal medulla
   -10% are b/l, 10% are malignant and 10% are familial!
   -Associated with MEN II
   -Remember that 33-50% of patients have sustained hypertension !
   -Suspect it if refractory to treatment
   -Screen for serum or urine metanephrines
   -CT adrenals or/and MIBG scan (meta-iodo-benzyl-guanidine) to detect tumors