What labs are included in the workup for refractory hypertension?

From the Guidelines

The workup for refractory hypertension should include labs such as urinalysis, blood glucose levels, hematocrit, lipid panel, basic metabolic panel, and calcium levels to identify potential secondary causes and end-organ damage. When evaluating refractory hypertension, it is crucial to consider identifiable causes of hypertension, such as sleep apnea, nonsteroidal anti-inflammatory drug use, chronic kidney disease, endocrine causes, renovascular disease, and coarctation 1. The initial laboratory assessment should include:

• Urinalysis to check for protein or blood
• Blood glucose levels to assess for diabetes mellitus
• Hematocrit to evaluate for potential anemia or polycythemia
• Lipid panel to assess cardiovascular risk
• Basic metabolic panel (BMP) to assess kidney function and electrolytes, particularly potassium, sodium, and creatinine
• Calcium levels to evaluate for potential hyperparathyroidism These tests are essential because refractory hypertension often stems from undiagnosed secondary causes, and identifying these underlying conditions can lead to specific treatments that effectively control blood pressure where standard antihypertensive regimens have failed 1. Additional testing may be necessary based on the patient's clinical presentation and initial laboratory results, but the above labs should be included in the initial workup for refractory hypertension.

From the Research

Refractory Hypertension Workup Labs

The workup for refractory hypertension involves several laboratory tests to identify underlying causes. Some of the key labs included in this workup are:

• Plasma aldosterone and renin levels to evaluate for primary aldosteronism, as seen in a case report of a 32-year-old woman with resistant hypertension 2
• Urinary protein and creatinine levels to assess for early renal damage, which can be an indicator of secondary hypertension 3
• Serum aldosterone and plasmatic renin activity (PRA) ratio to differentiate between unilateral and bilateral renal artery stenosis 4
• Renal function tests, such as glomerular filtration rate (GFR), to evaluate kidney function
• Other tests, such as renal Doppler ultrasound, digital subtraction angiography (DSA), and Duplex ultrasound, may also be used to diagnose renal artery stenosis and other secondary causes of hypertension 5, 6

Laboratory Tests for Secondary Hypertension

Secondary hypertension can be caused by various underlying conditions, including renal artery stenosis, primary aldosteronism, and kidney disease. Laboratory tests can help identify these conditions, including:

• Aldosterone/renin ratio (ARR) to diagnose primary aldosteronism, although this may be compromised in cases of non-suppressed renin levels 2
• Urinary protein and creatinine levels to assess for early renal damage 3
• Serum aldosterone and PRA levels to evaluate for renal artery stenosis and other secondary causes of hypertension 4
• Renal scintigraphic captopril test to diagnose renovascular hypertension 5

Imaging Studies for Refractory Hypertension

Imaging studies, such as renal Doppler ultrasound, DSA, and Duplex ultrasound, can help diagnose renal artery stenosis and other secondary causes of hypertension. These tests can:

• Evaluate blood flow to the kidneys and detect any blockages or narrowing of the renal arteries 5, 6
• Assess kidney function and structure 3
• Help guide treatment decisions, such as angioplasty or surgery, for renal artery stenosis 2, 6