Diagnostic Workup for Worsening Blood Pressure Control
When a patient's previously controlled hypertension worsens, immediately assess medication adherence, confirm true hypertension with home or ambulatory monitoring, and evaluate for secondary causes before intensifying therapy. 1, 2
Initial Assessment Steps
Confirm True Hypertension
- Verify elevated readings with home blood pressure monitoring (≥135/85 mmHg) or 24-hour ambulatory monitoring (≥130/80 mmHg) to rule out white-coat hypertension, which is a common cause of apparent treatment failure 1, 3
- Ensure proper blood pressure measurement technique is being used, as improper technique can falsely elevate readings 2
Assess Medication Adherence
- Non-adherence is the most common cause of apparent treatment resistance and must be ruled out before adding medications 1, 3
- Consider switching to single-pill combination therapy to improve adherence if the patient is on multiple separate medications 2
Evaluate for Interfering Substances
- NSAIDs are the most common interfering substance and can significantly blunt antihypertensive efficacy 3, 4
- Heavy alcohol intake (>2 drinks/day for men, >1 drink/day for women) contributes to resistant hypertension 3
- High dietary sodium intake (>2g/day) undermines blood pressure control 1, 3
- Review all over-the-counter medications, supplements, and decongestants 3
Screen for Secondary Causes
Most Common Secondary Causes to Evaluate
- Obstructive sleep apnea: Screen with history of snoring, witnessed apneas, daytime somnolence, and large neck circumference; consider polysomnography if suspected 3, 4
- Primary hyperaldosteronism: Check morning aldosterone-to-renin ratio, especially if hypokalemia is present 3, 4
- Chronic kidney disease: Measure serum creatinine and estimated GFR, as CKD is a common cause of fluid retention and resistant hypertension 3, 4
- Renovascular disease: Consider in patients with abrupt onset of hypertension, especially if age >55 years or <30 years, or if there's an abdominal bruit 4
Additional Considerations
- Thyroid dysfunction: Check TSH if not recently done 4
- Pheochromocytoma: Consider if episodic symptoms (headache, palpitations, sweating) are present 4
- Cushing's syndrome: Evaluate if clinical features suggest hypercortisolism 4
Assess Current Treatment Adequacy
Evaluate Medication Regimen
- Suboptimal therapy is the most common reason for failure to reach blood pressure goal after ruling out adherence issues 3
- Verify that current medications are at optimal doses before adding additional agents 1, 4
- Ensure a long-acting diuretic is included, as inadequate diuretic therapy is observed in nearly half of patients with resistant hypertension 4
Check for Volume Overload
- Fluid retention from inadequate diuretic dosing is a major contributor to resistant hypertension 3, 4
- Consider increasing diuretic dose or switching from hydrochlorothiazide to chlorthalidone (longer-acting) or a loop diuretic if GFR <30 mL/min 1, 4
Lifestyle Modification Assessment
- Reinforce sodium restriction to <2g/day, which can provide additive blood pressure reduction of 10-20 mmHg 1
- Assess weight status and recommend weight loss if BMI ≥25 kg/m², as obesity contributes to resistant hypertension 1, 3
- Verify regular physical activity (≥150 minutes/week of moderate-intensity exercise) 5
- Confirm alcohol moderation or elimination 5
Timeline for Reassessment
- Reassess blood pressure within 2-4 weeks after any intervention or medication adjustment 1, 2
- Target achieving blood pressure goal (<140/90 mmHg minimum, ideally <130/80 mmHg for higher-risk patients) within 3 months of treatment modification 1, 2