From the Guidelines
Chronic Kidney Disease (CKD) laboratory results should be interpreted based on key measurements including estimated glomerular filtration rate (eGFR), serum creatinine, blood urea nitrogen (BUN), and urine albumin-to-creatinine ratio (UACR), with a focus on early detection and treatment to prevent adverse outcomes, as recommended by the most recent guidelines 1. When interpreting CKD laboratory results, it is essential to consider the following key measurements:
- eGFR, which measures how well the kidneys filter blood, with normal values being >90 mL/min/1.73m²
- Serum creatinine, which increases as kidney function declines, with normal ranges being 0.7-1.3 mg/dL for men and 0.6-1.1 mg/dL for women
- BUN, another waste product that rises with kidney dysfunction, with normal values being 7-20 mg/dL
- UACR, which detects protein leakage in urine, with normal values being <30 mg/g Other important labs include electrolytes like potassium, sodium, calcium, and phosphorus, which kidneys help regulate; complete blood count to check for anemia, common in CKD; and parathyroid hormone levels, which often rise with kidney disease. Regular monitoring of these values helps track disease progression and guide treatment decisions, with CKD being staged from 1-5 based primarily on eGFR values, and stage 5 representing kidney failure requiring dialysis or transplantation, as outlined in recent guidelines 1. The most recent guidelines emphasize the importance of early detection and treatment of CKD to prevent adverse outcomes, such as cardiovascular disease and kidney failure, and recommend regular monitoring of laboratory values to guide treatment decisions 1. Key considerations in interpreting CKD laboratory results include:
- The definition of CKD as abnormalities of kidney structure or function, present for at least 3 months with implications for health, as defined by recent guidelines 1
- The evaluation of renal function using serum creatinine and an estimated glomerular filtration rate (eGFR) equation, preferably race-free CKD-EPI, and typically for proteinuria, as recommended by recent guidelines 1
- The importance of intensive BP control in patients with CKD to reduce rates of adverse outcomes, as outlined in recent guidelines 1.
From the Research
Interpretation of Chronic Kidney Disease (CKD) Laboratory Results
The interpretation of CKD laboratory results is crucial for identifying and managing the disease. The two key laboratory tests used to identify CKD are:
- Estimated glomerular filtration rate (eGFR), which measures kidney function 2
- Urine albumin-to-creatinine ratio (UACR), which measures kidney damage 2
Laboratory Tests for CKD
The eGFR test is used to assess kidney function, and the results are classified into five stages based on the severity of kidney damage 3. The UACR test is used to detect albuminuria, which is a sign of kidney damage 2.
Management of CKD
The management of CKD involves a multidisciplinary approach, including:
- Blood pressure control 4, 3, 5
- Glycemic control in diabetic patients 4, 5
- Reduction of proteinuria 4, 3, 5
- Lifestyle modifications, such as dietary changes, physical activity, and smoking cessation 3, 5
- Regular monitoring of kidney function and referral to a nephrologist for patients with advanced CKD or other complications 4, 3, 5
Accurate Assessment of GFR
Accurate assessment of GFR is essential for diagnosing and managing CKD. Alternative filtration markers, such as cystatin C, beta-trace protein, and beta-2 microglobulin, may be used in combination with creatinine to estimate GFR 6. However, the choice of equation used to estimate GFR may not significantly affect management decisions 6.