What is the initial treatment approach for a patient with secondary hypertension in the Philippines, considering underlying causes such as renal disease or adrenal gland disorders?

Treatment of Secondary Hypertension: Philippine Guidelines

Initial Treatment Approach

The primary treatment strategy for secondary hypertension in the Philippines is to identify and treat the underlying cause while simultaneously optimizing blood pressure control with appropriate antihypertensive medications. 1

The 2020 Philippine Clinical Practice Guidelines for hypertension emphasize that secondary causes must be recognized early to prevent irreversible target organ damage and enable potentially curative management. 1

Diagnostic Confirmation Before Treatment

Before initiating treatment, confirm true secondary hypertension by:

• Excluding pseudoresistance through proper blood pressure measurement technique, ruling out white coat effect with 24-hour ambulatory monitoring, and verifying medication adherence 2, 3
• Identifying the specific underlying cause using targeted investigations based on clinical presentation 2, 1
• Performing basic screening including serum sodium, potassium, creatinine with eGFR, urinalysis, fasting glucose or HbA1c, lipid profile, thyroid function tests, and ECG 4, 2

Cause-Specific Treatment Strategies

Primary Aldosteronism (8-20% of resistant hypertension cases)

• For unilateral disease: Surgical adrenalectomy is the treatment of choice and can be curative 4, 2
• For bilateral disease: Medical therapy with mineralocorticoid receptor antagonists 4, 2
  • Spironolactone 50-100 mg daily is the most widely used agent 2
  • Monitor serum potassium (must be <4.5 mmol/L) and ensure eGFR >45 ml/min/1.73m² before initiating 2, 3

Renovascular Disease

• For fibromuscular dysplasia (common in young women): Percutaneous transluminal renal angioplasty without stenting is the treatment of choice with high success rates 4, 2, 3
• For atherosclerotic renal artery stenosis (common in older adults): Medical therapy with optimal cardiovascular risk management is recommended 4, 2
• Avoid combining two RAS blockers (ACE inhibitor plus ARB) as this is not recommended 2
• Monitor renal function carefully when using RAS blockers 2

Renal Parenchymal Disease

• Use RAS blockers (ACE inhibitors or ARBs) as first-line agents for renoprotection 3
• Address the underlying renal disease with specific treatments 2
• For patients with creatinine clearance ≤30 mL/min, start enalapril at 2.5 mg once daily and titrate to maximum 40 mg daily 5

Obstructive Sleep Apnea (25-50% of resistant hypertension)

• CPAP therapy for moderate-severe cases is the primary treatment 2, 3
• Weight loss is essential, particularly for obese patients 2, 3
• Consider mandibular advancement devices as alternative 4

Pheochromocytoma/Paraganglioma

• Requires specialized management with alpha-blockade before beta-blockade, followed by surgical resection 4
• Refer to endocrinology or specialized hypertension center 2

Drug-Induced Hypertension

• Review and discontinue causative agents including NSAIDs, steroids, oral contraceptives, decongestants, amphetamines, and immunosuppressive agents 2, 3
• This should be assessed before extensive workup 2

Antihypertensive Medication Strategy While Addressing Underlying Cause

First-Line Agents

• Use thiazide-like diuretics (not classic thiazides), calcium channel blockers, ACE inhibitors, or ARBs as initial agents 3
• Ensure optimal doses of three first-line agents including a RAS blocker, calcium channel blocker, and diuretic 6

For Resistant Hypertension (BP >140/90 mmHg despite 3+ medications)

• Add spironolactone as fourth-line agent (25-50 mg daily) even with normal aldosterone levels, if serum potassium <4.5 mmol/L and eGFR >45 ml/min/1.73m² 4, 2, 6
• Use loop diuretics instead of thiazides if eGFR <30 ml/min/1.73m² 2
• Consider renal denervation for resistant hypertension uncontrolled despite optimal three-drug combination 2

Essential Lifestyle Modifications

All patients require comprehensive lifestyle interventions regardless of the underlying cause:

• Sodium restriction to <1500 mg/day 3, 6
• Potassium supplementation to 3500-5000 mg/day (unless contraindicated by hyperkalemia or renal dysfunction) 3
• Weight reduction of at least 1 kg if overweight/obese 3
• Physical activity of 90-150 minutes/week 3
• Alcohol moderation to ≤2 drinks/day in men and ≤1 drink/day in women 3
• DASH diet emphasizing fruits, vegetables, whole grains, and low-fat dairy 3

Critical Pitfalls and Caveats

• Delayed diagnosis leads to irreversible vascular remodeling and target organ damage, resulting in residual hypertension even after treating the underlying cause 2, 3
• Secondary hypertension is often underrecognized despite affecting 5-10% of hypertensive patients 2, 7, 8
• Young age of onset (<30 years) strongly warrants thorough evaluation for secondary causes even when initial screening appears normal 2, 6
• Some patients require lifelong antihypertensive therapy even after successfully treating the underlying cause 2
• Monotherapy has been used in >80% of Filipino patients, which explains poor BP control rates and should be avoided 9

Monitoring and Follow-up

• Regular monitoring of blood pressure using home BP monitoring in addition to office measurements 6
• Monitor renal function and electrolytes throughout treatment, especially when using spironolactone or RAS blockers 2, 3
• Reassess for secondary causes if BP control deteriorates after initial stabilization 6
• Refer to specialized hypertension center if BP remains uncontrolled despite optimization of therapy with 4+ medications 3, 6