What tests are needed for a patient with persistent hypertension, considering their demographic information, past medical history, and potential underlying causes?

Evaluation of Persistent Hypertension

All patients with persistent hypertension require a focused set of routine laboratory tests and a 12-lead ECG to assess cardiovascular risk, detect target organ damage, and screen for secondary causes. 1

Essential Routine Laboratory Tests

The following tests should be performed in every patient with persistent hypertension:

Basic Metabolic Panel

• Serum sodium and potassium to detect electrolyte abnormalities, particularly hypokalemia which suggests primary aldosteronism 1
• Serum creatinine with estimated glomerular filtration rate (eGFR) to assess kidney function and detect chronic kidney disease 1

Metabolic Assessment

• Fasting blood glucose or HbA1c to screen for diabetes, present in 15-20% of hypertensive patients 1, 2
• Lipid profile (total cholesterol and HDL cholesterol ratio) to assess cardiovascular risk 1

Urine Testing

• Dipstick urinalysis to detect blood and protein, which may indicate renal parenchymal disease 1
• Urinary albumin-to-creatinine ratio to assess for kidney damage and proteinuria 1, 2

Cardiac Assessment

• 12-lead electrocardiogram to detect left ventricular hypertrophy, atrial fibrillation, and ischemic heart disease 1

Additional Screening

• Thyroid-stimulating hormone (TSH) to exclude thyroid disease as a secondary cause 2, 3
• Serum uric acid levels as part of comprehensive cardiovascular risk assessment 1

When to Pursue Additional Testing for Secondary Hypertension

Consider expanded testing if any of the following red flags are present:

Clinical Red Flags Requiring Further Investigation

• Age of onset <30 years or >55 years 4, 3
• Abrupt onset or sudden worsening of previously controlled blood pressure 4, 3
• Severe hypertension (>180/120 mmHg) or resistant hypertension (uncontrolled on ≥3 medications including a diuretic) 2, 3
• Target organ damage disproportionate to duration or severity of hypertension 4, 3

Symptoms Suggesting Specific Secondary Causes

For Primary Aldosteronism (8-20% of resistant hypertension):

• Muscle weakness, tetany, cramps, or arrhythmias suggesting hypokalemia 1, 2
• Plasma aldosterone-to-renin ratio should be measured, as it has high negative predictive value for screening 2, 3

For Renovascular Disease:

• Flash pulmonary edema, abrupt onset hypertension, or early-onset hypertension in women (suggesting fibromuscular dysplasia) 2, 3
• Renal ultrasound with Doppler followed by CT or MR angiography if positive 1, 2

For Pheochromocytoma:

• Sweating, palpitations, frequent headaches, or episodic symptoms with labile hypertension 1, 3
• Plasma free metanephrines or 24-hour urinary metanephrines if clinically suspected 1, 3

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

• Snoring, daytime sleepiness, obesity, neck circumference >40 cm 1, 3
• Polysomnography or home sleep apnea testing if suspected 2, 3

For Cushing Syndrome:

• Fatty deposits, colored striae, weight gain, or other cushingoid features 1, 4
• Late-night salivary cortisol or other screening tests for cortisol excess 1

Advanced Imaging When Indicated

These tests should be reserved for specific clinical scenarios:

• Echocardiography for patients with ECG abnormalities, suspected left ventricular hypertrophy, systolic/diastolic dysfunction, or to evaluate for aortic coarctation 1, 2
• Carotid ultrasound to assess for atherosclerotic plaques and stenosis in patients with cardiovascular disease 1
• Fundoscopy if blood pressure >180/110 mmHg to evaluate for hypertensive emergency and retinal changes 1, 3
• Renal/adrenal imaging (ultrasound, CT, or MRI) when renovascular disease or adrenal lesions are suspected 1, 2

Critical Pitfalls to Avoid

• Do not stage hypertension on a single blood pressure reading—multiple measurements over time are required for accurate diagnosis 5
• Do not order expensive imaging studies before completing basic laboratory screening—this leads to unnecessary costs without improving outcomes 3, 6
• Do not overlook medication-induced hypertension—NSAIDs, decongestants, oral contraceptives, and corticosteroids can elevate blood pressure 4
• Do not fail to assess cardiovascular risk factors—more than 50% of hypertensive patients have additional risk factors including diabetes, dyslipidemia, and obesity 1

Important Note on Recent Guideline Changes

The 2024 European Society of Cardiology guidelines now recommend measuring renin and aldosterone in all adults with confirmed hypertension (Class IIa recommendation), representing a significant shift toward broader screening for primary aldosteronism 3. This reflects growing recognition that primary aldosteronism is more common than previously thought, affecting 8-20% of patients with resistant hypertension 2, 3.