Recommended Diagnostic Tests for Primary Hypertension
For a patient with suspected primary hypertension, obtain the following basic laboratory tests: fasting blood glucose, complete blood count, lipid profile, serum creatinine with estimated glomerular filtration rate (eGFR), serum electrolytes (sodium, potassium, calcium), thyroid-stimulating hormone (TSH), urinalysis, and a 12-lead electrocardiogram. 1
Core Laboratory Panel
The essential blood tests include:
- Fasting blood glucose to identify diabetes mellitus, which significantly increases cardiovascular risk and lowers treatment thresholds 1, 2
- Complete blood count (CBC) to detect anemia or other hematologic abnormalities that may affect management 1, 2
- Lipid profile (total cholesterol, LDL, HDL, triglycerides) for cardiovascular risk stratification 1, 2
- Serum creatinine with eGFR to assess kidney function and detect chronic kidney disease 1, 2
- Serum electrolytes (sodium, potassium, calcium) to detect abnormalities that may suggest secondary causes like primary aldosteronism 1, 2
- Thyroid-stimulating hormone (TSH) to easily detect hypothyroidism and hyperthyroidism, both remediable causes of hypertension 1, 2
Urine Testing
- Urinalysis to screen for kidney disease 1
- Urinary albumin-to-creatinine ratio is preferred over urine dipstick alone, as it is more sensitive for detecting early kidney damage and cardiovascular risk 2, 3
Cardiac Evaluation
- 12-lead electrocardiogram (ECG) to detect left ventricular hypertrophy, atrial fibrillation, and ischemic heart disease 1, 2, 3
Clinical Context and Rationale
These tests serve multiple purposes beyond confirming hypertension. More than 50% of hypertensive patients have additional cardiovascular risk factors such as diabetes (15-20%), lipid disorders (30%), obesity (40%), and metabolic syndrome (40%), which proportionally increase the risk of coronary, cerebrovascular, and renal diseases. 1, 3
Recent evidence demonstrates that baseline laboratory testing significantly improves blood pressure control—patients receiving complete workup achieved better systolic blood pressure control at 12 months (129.9 mmHg) compared to those with partial workup (142.8 mmHg). 4 These tests also help unmask important comorbidities: 8.4% had undiagnosed diabetes, 54.2% had elevated LDL cholesterol, and 7.5% had chronic kidney disease with eGFR <60 mL/min/1.73m². 4
Optional Testing
Consider these additional tests when clinically indicated:
- Echocardiogram if ECG shows abnormalities, cardiac symptoms are present, or detection of left ventricular hypertrophy would influence treatment decisions 1, 3
- Uric acid as part of the initial evaluation, particularly since elevated levels are common in hypertension (25% prevalence) 1, 2
Important Clinical Pitfalls to Avoid
- Do not use urine dipstick alone for albuminuria screening—always obtain urinary albumin-to-creatinine ratio for more sensitive detection of early kidney damage 2
- Do not skip the ECG even in young patients, as it is essential for detecting left ventricular hypertrophy and arrhythmias 2
- Do not overlook secondary causes in patients with specific clinical clues: age <30 or >50 years at onset, resistant hypertension requiring >3 medications, sudden deterioration in previously controlled hypertension, or target organ damage disproportionate to hypertension duration 5
- Confirm hypertension with repeated measurements before extensive workup, but do not delay basic laboratory testing once hypertension is confirmed 2
Monitoring During Treatment
Serum sodium and potassium monitoring is helpful during diuretic or RAS blocker titration, while serum creatinine and urinary albumin serve as markers of chronic kidney disease progression. 1