What is the recommended diagnostic test for a 45-year-old man with flank pain, palpable bilateral renal masses, hypertension (High Blood Pressure), and impaired renal function (elevated creatinine and Blood Urea Nitrogen (BUN))?

Diagnostic Testing for Bilateral Renal Masses with Hypertension and Renal Impairment

CT angiography (CTA) is the recommended diagnostic test for this 45-year-old man with bilateral palpable renal masses, hypertension, and impaired renal function. 1

Clinical Presentation Analysis

The patient presents with:

• 45-year-old male
• 2-year history of dull, non-specific flank pain relieved by rest
• Hypertension (elevated BP)
• Palpable bilateral renal masses on examination
• Impaired renal function (creatinine 1.9mg/dL, BUN 24mg/dL)

This clinical picture strongly suggests renovascular disease, specifically bilateral renal artery stenosis, which is a common finding in hypertensive patients with renal impairment. The bilateral palpable masses and elevated blood pressure are particularly concerning for renovascular disease.

Diagnostic Test Selection

Among the options presented:

1. Coronary angiography
2. Stress echocardiography
3. Chest X-ray
4. CT angiography of the heart

Why CT Angiography (Option D) is the Correct Choice:

CT angiography is the most appropriate test because:

• It provides excellent visualization of renal arteries with high sensitivity and specificity for detecting renal artery stenosis 1, 2
• It can assess both the renal vasculature and parenchyma in a single examination, allowing evaluation of the bilateral renal masses 1
• It can identify atherosclerotic disease, which accounts for >90% of renal artery stenoses 1
• It allows assessment of the degree of stenosis, which is critical for determining management 1

The American College of Radiology guidelines indicate that CT angiography is highly effective for diagnosing renovascular hypertension, particularly in patients with impaired renal function 1.

Why Other Options Are Less Appropriate:

• Coronary angiography: While this patient may have cardiovascular risk factors, there's no indication of coronary artery disease requiring direct coronary evaluation
• Stress echocardiography: Not indicated as the primary test when renovascular disease is the suspected cause of hypertension
• Chest X-ray: Too limited in scope to evaluate renovascular disease or renal masses

Risk Considerations

While there is concern about contrast-induced nephropathy with CT angiography in patients with impaired renal function, recent data indicate that this risk is lower than previously thought 1. The diagnostic benefit outweighs the risk in this case given the clinical presentation strongly suggestive of renovascular disease.

Alternative Diagnostic Approaches

If CT angiography is contraindicated:

• Duplex Doppler ultrasound could be considered as an initial screening test, though it is operator-dependent and may be limited by body habitus 1, 2
• MR angiography is another alternative but may be limited in patients with significantly impaired renal function due to concerns about nephrogenic systemic fibrosis 1

Key Diagnostic Parameters

For the diagnosis of renal artery stenosis, key parameters include:

• Peak systolic velocity >200-300 cm/s (sensitivity 91%, specificity 75-96%)
• Renal-to-aortic ratio >3.5 (specificity 96.7%)
• Presence of tardus-parvus waveform 2

CT angiography provides the most comprehensive assessment of these parameters and the renal parenchyma in this clinical scenario.