What laboratory tests are indicated to rule out secondary hypertension?

From the Guidelines

When ruling out secondary hypertension, I recommend ordering a comprehensive panel of laboratory tests, including basic metabolic panel (BMP), urinalysis, thyroid function tests (TSH, free T4), plasma aldosterone concentration and plasma renin activity, 24-hour urine collection for metanephrines, catecholamines, and vanillylmandelic acid (VMA), and a morning cortisol or overnight dexamethasone suppression test, as suggested by the 2024 ESC guidelines 1.

Key Laboratory Tests

• Basic metabolic panel (BMP) to assess kidney function and electrolytes
• Urinalysis to check for proteinuria or hematuria
• Thyroid function tests (TSH, free T4) to rule out hyperthyroidism
• Plasma aldosterone concentration and plasma renin activity with calculation of the aldosterone-to-renin ratio to evaluate for primary aldosteronism
• 24-hour urine collection for metanephrines, catecholamines, and vanillylmandelic acid (VMA) to screen for pheochromocytoma
• Morning cortisol or overnight dexamethasone suppression test to assess for Cushing's syndrome

Additional Considerations

• Measuring serum calcium and parathyroid hormone levels to rule out hyperparathyroidism
• Considering the patient's clinical presentation, including age of onset, severity of hypertension, presence of symptoms suggesting a specific etiology, and response to conventional antihypertensive therapy, as recommended by the 2024 ESC guidelines 1 and the 2017 ACC/AHA guidelines 1

Rationale

The selection of tests should be guided by the patient's clinical presentation and the prevalence of secondary hypertension causes, as outlined in the 2017 ACC/AHA guidelines 1. The 2024 ESC guidelines 1 recommend screening for primary aldosteronism by renin and aldosterone measurements in all adults with confirmed hypertension, and the 2024 ESC guidelines also recommend comprehensive screening for the main causes of secondary hypertension in young adults (<40 years of age) 1.

From the Research

Secondary Hypertension Diagnosis

To rule out secondary hypertension, several labs and tests can be considered, including:

• Blood tests to check for primary aldosteronism, such as aldosterone and renin levels 2, 3
• Urine tests to check for pheochromocytoma and paraganglioma, such as metanephrines and catecholamines 2, 3
• Imaging tests, such as CT or MRI scans, to check for renovascular hypertension and other causes of secondary hypertension 2, 3
• Sleep studies to check for obstructive sleep apnea 2, 3
• Blood tests to check for Cushing's syndrome, such as cortisol levels 2

Patient Selection for Screening

Screening for secondary hypertension should be based on clinical suspicion and patient characteristics, such as:

• Resistant hypertension 4, 5
• Age 5, 6
• Family history 4
• Clinical history 4

Diagnostic Approach

The diagnostic approach to secondary hypertension involves:

• Initial screening with basic labs and tests 6
• Further testing and evaluation based on the results of the initial screening 6
• Specialist input for specific diagnostic procedures 6