From the Guidelines
A comprehensive kidney health evaluation should include serum creatinine with eGFR calculation, blood urea nitrogen (BUN), urinalysis with protein-to-creatinine ratio, cystatin C measurement, and kidney ultrasound imaging, as these tests provide a more complete picture of kidney function and structure than relying on GFR alone. According to the most recent guidelines, testing people at risk for and with chronic kidney disease (CKD) using both urine albumin measurement and assessment of glomerular filtration rate (GFR) is recommended 1. The combination of creatinine and cystatin C provides the most accurate GFR estimation, and urinalysis can detect protein, blood, or other abnormalities that may indicate kidney damage before GFR declines. For those with diabetes, regular microalbuminuria testing is essential to detect early kidney damage, and blood pressure monitoring is also crucial as hypertension both causes and results from kidney disease 1. Some key points to consider in a comprehensive kidney health evaluation include:
- Assessing albuminuria and GFR more often for individuals at higher risk of CKD progression when measurement will impact therapeutic decisions 1
- Using a combination of serum creatinine, cystatin C, and urinalysis to detect kidney damage and estimate GFR
- Monitoring blood pressure and adjusting treatment as needed to slow CKD progression
- Considering lifestyle changes and medical treatments to reduce the risk of CKD progression and cardiovascular disease. Overall, a comprehensive approach to kidney health evaluation and management can help improve outcomes for individuals with CKD.
From the Research
Alternative Tests for Kidney Health
The Glomerular Filtration Test (GFT) is not the only test for assessing kidney health. Other methods include:
- Measuring serum creatinine and reporting estimated GFR based on serum creatinine (eGFRcr) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009 equation 2
- Measuring cystatin C and estimating GFR using cystatin C (eGFRcys) and serum creatinine (eGFRcr-cys) 2
- Measuring albuminuria through urine albumin and creatinine in an untimed spot urine collection and reporting albumin-to-creatinine ratio 2
- Measuring proteinuria, which has been widely used in real-world clinical practice, although its prognostic performance compared to albuminuria remains inconclusive 3
Advantages of Alternative Tests
Some alternative tests have advantages over the GFT, including:
- The albumin-to-creatinine ratio (ACR) measurement in a first-void spot urine specimen, which is the preferred method for assessment of albuminuria in both diabetic and non-diabetic patients 4
- The use of ACR assessments in CKD screening, which appears beneficial for a more accurate prediction of worse quality of life 5
- The measurement of urinary albuminuria and proteinuria, which is essential for the detection and risk stratification of people with chronic kidney disease (CKD) 4
Comparison of Tests
Studies have compared the performance of different tests, including:
- A comparison of urine dipstick and albumin:creatinine ratio for chronic kidney disease screening, which found that the urine dipstick test had poor sensitivity and high false-discovery rates for ACR ≥30 mg/g detection 5
- A comparison of the predictive performances of albuminuria and proteinuria in patients with CKD, which found that the predictive performance of proteinuria was superior in severe albuminuria and nephrotic-range proteinuria 3