What routine lab work is recommended for a patient with elevated blood pressure (hypertension) without a diagnosis of hypertension?

Routine Laboratory Work for Elevated Blood Pressure Without Diagnosis of Hypertension

For patients with elevated blood pressure without a diagnosis of hypertension, recommended routine laboratory work includes fasting blood glucose, complete blood count, lipid profile, serum creatinine with eGFR, serum electrolytes (sodium, potassium, calcium), thyroid-stimulating hormone, urinalysis, and a 12-lead ECG. 1

Core Laboratory Tests

The following tests are recommended as basic laboratory evaluation for all patients with elevated blood pressure:

• Fasting blood glucose - To screen for diabetes or prediabetes, which are common comorbidities 1
• Complete blood count (CBC) - To assess for anemia or other hematologic abnormalities 1
• Lipid profile - To evaluate cardiovascular risk factors 1
• Serum creatinine with estimated glomerular filtration rate (eGFR) - To assess kidney function and screen for chronic kidney disease 1
• Serum electrolytes (sodium, potassium, calcium) - To detect electrolyte imbalances that may contribute to or result from blood pressure elevation 1
• Thyroid-stimulating hormone (TSH) - To screen for thyroid disorders that can cause secondary hypertension 1
• Urinalysis - To detect proteinuria, hematuria, or other signs of kidney damage 1
• 12-lead electrocardiogram (ECG) - To assess for left ventricular hypertrophy or other cardiac abnormalities 1

Optional Laboratory Tests

Depending on clinical findings and risk factors, these additional tests may be considered:

• Urinary albumin-to-creatinine ratio (ACR) - Recommended by the European Society of Cardiology to detect early kidney damage 1
• Uric acid - May be considered as an optional test 1
• Echocardiography - Recommended when there are ECG abnormalities, signs or symptoms of cardiac disease 1

Diagnostic Approach

The diagnostic approach for elevated blood pressure should follow these steps:

1. Confirm elevated readings - Before ordering laboratory tests, confirm elevated BP with repeated measurements on more than one visit or with out-of-office measurements 1

2. Classify BP elevation - For screening office BP of 120-139/70-89 mmHg, out-of-office BP measurement is recommended using ambulatory blood pressure monitoring (ABPM) and/or home blood pressure monitoring (HBPM) 1

3. Order basic laboratory tests - Once elevated BP is confirmed, proceed with the core laboratory tests listed above 1

4. Consider cardiovascular risk assessment - Use tools like SCORE2 or SCORE2-OP to assess 10-year risk of cardiovascular disease 1

Special Considerations

• White coat hypertension - For patients with untreated SBP >130 mmHg but <160 mmHg or DBP >80 mmHg but <100 mmHg, screening for white coat hypertension using ABPM or HBPM before diagnosis is reasonable 1

• Masked hypertension - For patients with untreated office BPs between 120-129/75-79 mmHg, screening for masked hypertension with HBPM or ABPM is reasonable 1

• Follow-up testing - If moderate-to-severe chronic kidney disease is diagnosed, annual measurements of serum creatinine, eGFR, and urine ACR are recommended 1

Common Pitfalls to Avoid

• Overdiagnosis - Diagnosing hypertension based on a single elevated reading can lead to unnecessary treatment 1

• Underestimating white coat or masked hypertension - Relying solely on office BP measurements may miss these conditions, which affect 10-30% of patients 1

• Incomplete evaluation - Failing to perform basic laboratory tests may miss secondary causes of hypertension or target organ damage 1

• Delayed diagnosis - For significantly elevated BP (≥160/100 mmHg), confirmation should occur promptly (within 1 month) 1

By following these evidence-based recommendations for laboratory testing, clinicians can appropriately evaluate patients with elevated blood pressure, assess for target organ damage, and identify potential secondary causes of hypertension.