Hallmarks of Primary and Secondary Hypertension

George Thomas

Martin J. Schreiber

POINTS TO REMEMBER:

A complete history, physical examination, basic serum chemistries analysis, urinalysis, and ECG are recommended for the initial evaluation of a hypertensive patient.
Specific aspects of the patient’s history should include family history, sleep history, nonprescription medication use (nonsteroidal anti-inflammatory drugs, diet pills, decongestants, appetite suppressants, and herbal therapy), oral contraceptive pills, and use of alcohol and recreational drugs.
In most cases, the presence of significant arteriovenous nicking on fundoscopic examination indicates that the BP has been elevated for more than 6 months.
Physical exam findings suggesting a secondary cause of hypertension include an abdominal or flank bruit (renal artery stenosis), central obesity with abdominal striae and buffalo hump (Cushing syndrome), enlarged kidneys (polycystic kidney disease), or diminished pedal pulses and a discrepancy between arm and leg pressures (coarctation of the aorta).
Ambulatory blood pressure monitoring (ABPM) should be considered in the evaluation of patients with elevated office blood pressure readings but normal home readings and no evidence of end organ damage.
A shift in emphasis from diastolic to systolic blood pressure (BP) has occurred over the years as evidence has mounted that reflects the very strong, positive, and causal relationship between increasing levels of systolic BP and cardiovascular risk.
Patients presenting with BP > 180/110 mmHg should be classified as severe hypertension, hypertensive urgency, or hypertensive emergency based on clinical features.
- Severe hypertension: BP > 180/110 mmHg in the absence of symptoms beyond mild-to-moderate headache and without evidence of acute target organ damage. Management: Brief office observation, oral anti-hypertension medication, and short-term follow-up.
- Hypertensive urgency: BP >180/110 mmHg in the presence of significant symptoms such as severe headache or dyspnea but no or only minimal acute target organ damage. Management: Longer observation and treatment with oral agent with rapid onset of action with goal of lowering BP in 24 to 72 hours.
- Hypertensive emergency: BP very high (often >220/140 mmHg) with evidence of life-threatening organ dysfunction. Management: Admission to ICU and treatment with parenteral agent and goal to reduce BP by 15% to 25% within 4 hours.
Resistant hypertension is defined as the persistence of out-of-office BP levels >140/90 mmHg despite a three-drug regimen that includes a diuretic and should prompt investigation for a secondary cause.
Primary aldosteronism is the most common endocrine cause of secondary hypertension.
The best clues to the presence of primary aldosteronism include hypertension with spontaneous hypokalemia (<3.5 mEq/L), hypertension with provoked hypokalemia (<3.0 mEq/L during diuretic therapy), and hypertension with difficulty maintaining normokalemia despite potassium supplementation. However, not all patients with primary aldosteronism have hypokalemia.
The plasma aldosterone and plasma renin activity together can be used to screen for primary aldosteronism and a 24-hour urine aldosterone level can be used for confirmation.
Among patients with pheochromocytoma, 80% present with headache, 57% with sweating, 48% with paroxysmal hypertension, 39% with persistent hypertension, and 64% with palpitations.
The measurement of fractionated plasma-free metanephrines is the best test for familial pheochromocytoma, whereas 24-hour urine metanephrines and catecholamines provide adequate sensitivity and specificity for sporadic pheochromocytoma.
Phenoxybenzamine, a relatively nonspecific, complete, and prolonged α-1 blocker that has traditionally been used perioperatively in the setting of pheochromocytoma, is now often replaced by calcium channel blockers, angiotensin receptor blockers, and selective α-1 blockers.