What are the differences in treatment approaches for primary hypertension (HTN) versus secondary hypertension?

Treatment Approaches for Primary vs Secondary Hypertension

The fundamental difference in treatment approach between primary and secondary hypertension is that secondary hypertension requires identifying and treating the underlying cause, while primary hypertension is managed with standard antihypertensive therapy and lifestyle modifications.

Primary Hypertension Management

Primary hypertension (essential hypertension) is managed through a combination of lifestyle modifications and pharmacological therapy:

Lifestyle Modifications

• Weight loss for overweight/obese patients
• Sodium restriction to <1500 mg/day
• DASH diet (rich in fruits, vegetables, whole grains, low-fat dairy)
• Increased physical activity (90-150 minutes/week)
• Moderation of alcohol intake (≤2 drinks/day for men, ≤1 for women)
• Increased potassium intake (3500-5000 mg/day) 1

Pharmacological Therapy

First-line medications include:

• Thiazide or thiazide-like diuretics
• ACE inhibitors
• Angiotensin receptor blockers (ARBs)
• Calcium channel blockers (CCBs) 1

For stage 1 hypertension (130-139/80-89 mmHg), treatment decisions are based on ASCVD risk:

• If 10-year ASCVD risk ≥10%: initiate drug therapy plus lifestyle modifications
• If 10-year ASCVD risk <10%: start with lifestyle modifications alone 1

For stage 2 hypertension (≥140/90 mmHg), initiate drug therapy with two antihypertensive agents from different classes along with lifestyle modifications 1

Secondary Hypertension Management

Secondary hypertension requires a different approach focused on identifying and treating the underlying cause:

Step 1: Identification

Screen for secondary causes when clinical clues are present:

• Abrupt onset of hypertension
• Age <30 years at onset
• Previously well-controlled BP becoming resistant
• Resistant hypertension (≥3 medications including a diuretic)
• Refractory hypertension (≥5 medications including a diuretic)
• Unprovoked hypokalemia
• Onset of diastolic hypertension in older patients (≥65 years) 1

Step 2: Diagnosis of Specific Causes

Common causes and their diagnostic approaches:

1. Sleep Apnea

   • Clinical clues: snoring, daytime sleepiness, non-restorative sleep
   • Management: CPAP therapy and weight loss 1

2. Primary Aldosteronism

   • Present in ~20% of resistant hypertension cases
   • Diagnosis: Plasma aldosterone/renin ratio
   • Management: Adrenalectomy for unilateral disease; mineralocorticoid receptor antagonists for bilateral disease 1

3. Renal Artery Stenosis

   • Atherosclerotic or fibromuscular dysplasia
   • Management:
     • Atherosclerotic: Medical therapy is first-line
     • Fibromuscular dysplasia: Angioplasty without stenting
     • Consider revascularization for refractory hypertension, worsening renal function, or intractable heart failure 1

4. Pheochromocytoma

   • Clinical clues: BP lability, episodic pallor, dizziness
   • Diagnosis: 24-hour urinary metanephrines or plasma metanephrines
   • Management: Surgical removal after alpha-blockade 1

5. Cushing's Syndrome

   • Clinical clues: Central obesity, facial rounding, easy bruisability
   • Management: Treat underlying cause (surgical or medical) 1

Step 3: Specific Treatment

• Treat the underlying cause first rather than simply managing the hypertension
• Continue antihypertensive medications until the underlying cause is adequately addressed
• Monitor BP response to specific treatment of the underlying condition 1

Key Differences in Approach

1. Diagnostic Workup:

   • Primary HTN: Basic evaluation (labs, ECG)
   • Secondary HTN: Extensive workup based on suspected cause (imaging, specialized hormone tests) 1

2. Treatment Goals:

   • Primary HTN: BP control to <130/80 mmHg
   • Secondary HTN: Resolution of underlying cause plus BP control 1

3. Medication Selection:

   • Primary HTN: Standard first-line agents
   • Secondary HTN: May require specific agents based on etiology (e.g., mineralocorticoid receptor antagonists for primary aldosteronism) 1

4. Prognosis:

   • Secondary HTN: Potentially curable if underlying cause can be corrected
   • Primary HTN: Lifelong management typically required 1

Common Pitfalls to Avoid

1. Failing to screen for secondary causes in patients with resistant hypertension
2. Not addressing lifestyle factors in both primary and secondary hypertension
3. Delaying specialist referral for suspected secondary hypertension
4. Continuing standard antihypertensive therapy without addressing the underlying cause in secondary hypertension
5. Not monitoring for medication side effects or interactions that may worsen BP control

Remember that even when treating secondary hypertension, lifestyle modifications remain an important adjunct to specific therapies for the underlying cause.