What lab tests and medications are recommended to monitor and treat a patient with hypertension?

Laboratory Testing and Monitoring in Hypertension

Essential Initial Laboratory Tests

All patients with newly diagnosed hypertension should undergo a core panel of laboratory tests to assess cardiovascular risk, screen for secondary causes, and detect hypertension-mediated organ damage (HMOD). 1

Routine Initial Tests (Mandatory)

• Serum creatinine and estimated glomerular filtration rate (eGFR): Assess kidney function and cardiovascular risk 1
• Serum electrolytes (sodium and potassium): Screen for secondary hypertension (primary aldosteronism, Cushing's disease) and establish baseline before initiating therapy 1
• Fasting blood glucose and HbA1c (if glucose elevated): Assess cardiovascular risk and identify diabetes as a comorbidity 1
• Lipid profile: Total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides to assess cardiovascular risk 1
• Urinalysis with dipstick: Screen for proteinuria and hematuria 1
• Urinary albumin-to-creatinine ratio: Assess HMOD and cardiovascular risk 1
• 12-lead ECG: Detect atrial fibrillation, left ventricular hypertrophy, and ischemic heart disease 1
• Hemoglobin/hematocrit: Screen for polycythemia as a secondary cause 1
• Serum calcium: Screen for hyperparathyroidism 1
• Thyroid-stimulating hormone (TSH): Screen for thyroid disease as a secondary cause 1

Optional Tests for HMOD Assessment

These tests should be considered based on clinical context to visualize organ damage, which can motivate treatment adherence and overcome clinical inertia 1:

• Echocardiography: Assess for left ventricular hypertrophy, systolic/diastolic dysfunction, and previous myocardial infarction 1
• Carotid or femoral artery ultrasound: Detect atherosclerotic plaques 1
• Coronary artery calcium scoring by cardiac CT: Assess atherosclerotic burden 1
• Arterial stiffness measurement (carotid-femoral or brachial-ankle pulse wave velocity): Assess vascular HMOD 1
• High-sensitivity cardiac troponin and/or NT-proBNP: Detect subclinical cardiac damage 1
• Ankle-brachial index: Screen for peripheral artery disease 1
• Fundoscopy: Assess hypertensive retinopathy, particularly important in hypertensive emergencies 1

Monitoring During Antihypertensive Therapy

Timing of Follow-up Testing

• Recheck serum potassium and creatinine 2-4 weeks after initiating or uptitrating ACE inhibitors, ARBs, or diuretics to detect hyperkalemia, hypokalemia, or acute kidney injury 2, 3
• Reassess blood pressure within 2-4 weeks after any medication adjustment 2, 3
• Achieve target blood pressure within 3 months of initiating or modifying therapy 2, 3

Ongoing Monitoring in Patients with CKD

For patients with moderate-to-severe chronic kidney disease (eGFR <60 mL/min/1.73m²), repeat measurements of serum creatinine, eGFR, and urinary albumin-to-creatinine ratio at least annually. 1

Screening for Secondary Hypertension

Consider additional testing when clinical features suggest secondary causes 1:

• Primary aldosteronism: Aldosterone-renin ratio (screen if resistant hypertension, hypokalemia, or adrenal incidentaloma) 1
• Pheochromocytoma: Plasma free metanephrines (screen if paroxysmal hypertension, sweating, palpitations, headaches) 1
• Cushing syndrome: Late-night salivary cortisol or 24-hour urinary free cortisol (screen if central obesity, striae, proximal muscle weakness) 1
• Renovascular hypertension: Renal artery duplex ultrasound, CT angiography, or MR angiography (screen if resistant hypertension, acute rise in creatinine with ACE inhibitor/ARB, or abdominal bruit) 1
• Obstructive sleep apnea: Home sleep apnea testing or polysomnography (screen if snoring, daytime sleepiness, neck circumference >40 cm) 1

Common Pitfalls to Avoid

• Do not omit baseline testing before initiating therapy, as 36% of patients in real-world practice receive no laboratory monitoring within 6 months of starting antihypertensive medication 4
• Do not delay treatment intensification while waiting for laboratory results in patients with stage 2 hypertension (≥160/100 mmHg), as prompt action reduces cardiovascular risk 2
• Do not assume normal renal function without testing, as 6.7% of patients without comorbidities and 26.3% of multi-comorbid patients have renal dysfunction at hypertension diagnosis 5
• Do not overlook electrolyte abnormalities, which occur in 9.8% of patients without comorbidities and 20.5% of multi-comorbid patients 5

Frequency of Laboratory Abnormalities

Real-world data demonstrate that clinically significant abnormalities are common at hypertension diagnosis 5:

• Renal dysfunction: 6.7% in patients without comorbidities, 26.3% in multi-comorbid patients
• Electrolyte abnormalities: 9.8% in patients without comorbidities, 20.5% in multi-comorbid patients
• Diabetes: 13.4% in patients without comorbidities, 38.8% in multi-comorbid patients

These findings underscore the importance of comprehensive baseline testing, particularly in older patients and those with multiple comorbidities 5.