From the Guidelines
For diagnosing resistant hypertension, the most recent and highest quality study recommends several blood tests to identify potential underlying causes, including a basic metabolic panel, aldosterone and renin levels, thyroid function tests, and a lipid panel, as outlined in the 2024 ESC guidelines for the management of elevated blood pressure and hypertension 1.
Key Blood Tests for Resistant Hypertension
The following blood tests are crucial for diagnosing resistant hypertension:
- Basic metabolic panel to assess kidney function and detect electrolyte imbalances
- Aldosterone and renin levels to screen for primary aldosteronism
- Thyroid function tests to rule out thyroid disorders
- Lipid panel to evaluate cardiovascular risk Additional tests may include:
- Hemoglobin A1c to check for diabetes
- Urinalysis to detect protein or blood suggesting kidney damage
- 24-hour urinary metanephrines or plasma metanephrines to screen for pheochromocytoma in patients with episodic symptoms These tests help identify secondary causes of hypertension that may be contributing to treatment resistance, as emphasized in the 2024 ESC guidelines 1 and supported by other recent studies 1.
Importance of Hormonal Testing
Hormonal testing, particularly for primary aldosteronism, is crucial in diagnosing resistant hypertension, as it can affect up to 5-20% of cases and requires specific treatment approaches beyond standard antihypertensive therapy, as noted in the 2021 guideline-driven management of hypertension update 1.
Recent Guidelines and Recommendations
The 2024 ESC guidelines for the management of elevated blood pressure and hypertension 1 and other recent studies 1 emphasize the importance of a comprehensive diagnostic approach, including blood tests, to identify underlying causes of resistant hypertension and guide treatment decisions.
From the Research
Blood Tests for Resistant Hypertension
To diagnose resistant hypertension, several blood tests can be recommended:
- Routine laboratory work to reveal chronic kidney disease, which is the most common associated factor in resistant hypertension 2
- Plasma aldosterone concentration (PAC) to check for primary aldosteronism, a common secondary cause of resistant hypertension 3
- Renin level to evaluate the renin-angiotensin system, which plays a crucial role in blood pressure regulation 3
- Electrolyte panel to assess for any electrolyte imbalances that may be contributing to resistant hypertension
- Blood urea nitrogen (BUN) and creatinine to evaluate kidney function, as renal disease is a common cause of resistant hypertension 2, 4
Secondary Causes of Resistant Hypertension
Blood tests can also help identify secondary causes of resistant hypertension, such as:
- Primary aldosteronism, which can be diagnosed with a PAC and renin level 3
- Renovascular disease, which can be evaluated with renal artery stenosis testing 2
- Pheochromocytoma, which can be diagnosed with plasma metanephrine levels 2, 4
- Cushing's disease, which can be evaluated with cortisol levels 4
- Thyroid and parathyroid dysfunction, which can be assessed with thyroid-stimulating hormone (TSH) and parathyroid hormone (PTH) levels 4