What lab tests are recommended for a patient with hypertension?

Laboratory Workup for Hypertension

Essential laboratory tests are required for all patients with hypertension to assess cardiovascular risk, detect target organ damage, and screen for secondary causes of hypertension. 1

Basic Laboratory Tests (Required for All Hypertensive Patients)

• Blood tests:

  • Serum sodium and potassium (to screen for electrolyte abnormalities and primary aldosteronism) 1
  • Serum creatinine with estimated glomerular filtration rate (eGFR) (to assess kidney function) 1
  • Fasting blood glucose (to screen for diabetes/prediabetes) 1, 2
  • Complete lipid profile (total cholesterol, LDL, HDL, triglycerides) 1
  • Complete blood count (to evaluate for anemia) 2
  • Thyroid-stimulating hormone (TSH) (to screen for thyroid dysfunction) 1

• Urine tests:

  • Urinary albumin-to-creatinine ratio (preferred over dipstick urinalysis for detecting early kidney damage) 1, 2

• Cardiovascular assessment:

  • 12-lead ECG (to detect atrial fibrillation, left ventricular hypertrophy, ischemic heart disease) 1

Optional Tests (Based on Clinical Indication)

• Cardiovascular assessment:

  • Echocardiography (for suspected hypertensive heart disease, abnormal ECG, or uncontrolled hypertension) 1, 2
  • Carotid/femoral ultrasound (to assess for atherosclerotic plaque) 1
  • Ankle-brachial index (to detect peripheral arterial disease) 1

• Renal assessment:

  • Renal ultrasound (for patients with CKD, suspected renal parenchymal disease or renovascular hypertension) 1, 2
  • CT/MR angiography (when renovascular hypertension is suspected) 1

• Additional tests:

  • Serum uric acid (for risk stratification) 1, 2
  • Liver function tests 1
  • Fundoscopy (to assess for hypertensive retinopathy) 1

Tests for Secondary Hypertension (When Suspected)

• Aldosterone-renin ratio (for primary aldosteronism) 1
• Plasma free metanephrines (for pheochromocytoma) 1
• Late-night salivary cortisol (for Cushing's syndrome) 1
• Sleep study (for obstructive sleep apnea) 2

Clinical Impact of Laboratory Testing

• Complete laboratory workup is associated with better blood pressure control at 12 months compared to partial workup (129.9 ± 13.6 mmHg vs. 142.8 ± 18.9 mmHg) 3
• Laboratory tests help identify comorbidities that increase cardiovascular risk:
  • Diabetes (found in 7.5-8.4% of newly diagnosed hypertensive patients) 3
  • Dyslipidemia (found in >50% of hypertensive patients) 3
  • Chronic kidney disease (found in 7.5% of hypertensive patients) 3

Common Pitfalls to Avoid

• Using urine dipstick alone instead of quantitative albumin-to-creatinine ratio can miss early kidney damage 1, 2
• Overlooking the need for echocardiography in patients with uncontrolled hypertension 2
• Failing to repeat laboratory tests in patients with abnormal findings or CKD (annual monitoring recommended) 1
• Relying solely on office BP measurements without confirming with home or ambulatory monitoring 2
• Neglecting to assess for target organ damage, which influences treatment decisions and prognosis 1, 2

Frequency of Monitoring

• For patients with moderate-to-severe CKD, repeat measurements of serum creatinine, eGFR, and urine albumin-to-creatinine ratio at least annually 1
• For patients with abnormal findings, more frequent monitoring may be necessary based on clinical judgment 1

By following this comprehensive laboratory workup approach, clinicians can better assess cardiovascular risk, detect target organ damage, identify secondary causes of hypertension, and optimize treatment strategies to improve patient outcomes.