What further investigations are recommended for a patient with impaired renal function and hypertension on rosuvastatin (statin) therapy?

Further Investigations for a Patient with Impaired Renal Function and Hypertension on Rosuvastatin

For a patient with impaired renal function and hypertension on rosuvastatin therapy, comprehensive renal assessment including duplex ultrasound of the kidneys should be performed as the first-line investigation. 1

Initial Laboratory Investigations

• Serum creatinine and estimated glomerular filtration rate (eGFR) should be measured to assess the severity of renal impairment 1, 2
• Urinary albumin-to-creatinine ratio (ACR) should be obtained to evaluate for proteinuria, which indicates glomerular filtration barrier derangement 1
• Blood Urea Nitrogen (BUN) should be measured as it correlates with reduced renal blood flow 2
• Complete electrolyte panel to assess for imbalances associated with renal dysfunction 1

Imaging Studies Based on Renal Function

For eGFR < 30 mL/min/1.73 m²:

• Duplex ultrasound of the kidneys with Doppler is the recommended first-line imaging modality (rated 9/9 for appropriateness) 1
• Unenhanced MR angiography (MRA) without contrast is the preferred second-line option (rated 7/9) 1
• CT angiography with IV contrast should be used with caution due to risk of contrast-induced nephropathy 1

For Normal or Moderately Impaired Renal Function:

• MR angiography without and with IV contrast or CT angiography with IV contrast are equally appropriate (both rated 8/9) 1
• Duplex ultrasound remains a highly appropriate option (rated 7/9) 1

Specific Parameters to Assess on Renal Ultrasound

• Peak systolic velocity (PSV) ≥200 cm/s indicates >50% renal artery stenosis 1
• Renal-aortic peak flow velocity ratio (RAR) >3.5 indicates ≥60% stenosis 1
• Side-to-side difference of intrarenal resistance index ≥0.5 suggests significant stenosis 1
• Kidney size (<7 cm suggests non-viable kidney, >8 cm indicates viability) 1
• Renal cortex thickness (distinct cortex >0.5 cm indicates viability) 1

Cardiovascular Assessment

• 12-lead ECG should be performed to assess for left ventricular hypertrophy and arrhythmias 1
• Echocardiography should be considered to evaluate for hypertensive heart disease, especially if the ECG is abnormal 1
• Assessment for other target organ damage such as retinopathy through fundoscopy 1
• Brain MRI may be considered in elderly hypertensive patients to evaluate for white matter hyperintensities and silent infarcts 1

Rosuvastatin-Specific Considerations

• Rosuvastatin exposure increases significantly in patients with severe renal impairment (CL_cr < 30 mL/min/1.73 m²) 3
• For patients with severe renal impairment not on hemodialysis, rosuvastatin dosage should not exceed 10 mg daily 3
• Monitor for signs of myopathy, which is more common in patients with renal impairment on statin therapy 3
• Consider evaluating for transient proteinuria, which can occur with rosuvastatin but does not typically indicate declining renal function 4, 5

Follow-up Investigations

• In patients with confirmed renal artery stenosis, regular follow-up should include laboratory tests to assess renal function, blood pressure monitoring, and renal artery duplex ultrasound 1
• For patients with moderate-to-severe CKD, measurements of serum creatinine, eGFR, and urine ACR should be repeated at least annually 1

By following this comprehensive investigative approach, clinicians can properly assess the extent of renal impairment, identify potential renovascular causes of hypertension, and optimize rosuvastatin therapy to minimize risks while maintaining cardiovascular benefits.