From the Guidelines
Laboratory tests that indicate kidney failure primarily include a decreased glomerular filtration rate (GFR) below 15 mL/min/1.73m², which is a definitive marker of end-stage kidney disease, as well as elevated blood urea nitrogen (BUN) and serum creatinine levels 1. These tests are crucial for diagnosing kidney failure, as the condition often progresses silently until significant function is lost. Key laboratory findings that suggest kidney failure include:
- Elevated serum creatinine and BUN levels, indicating impaired kidney function
- Electrolyte imbalances, such as high potassium, phosphorus, and low calcium, which can be detected through a comprehensive metabolic panel
- Protein, blood, or abnormal cells in the urine, as revealed by urinalysis
- A decreased GFR, which is the best measure of overall kidney function in health and disease, with a level less than 15 mL/min per 1.73 m2 representing kidney failure 1
- Anemia, as indicated by a complete blood count, due to decreased erythropoietin production Additional tests, such as cystatin C levels and urine albumin-to-creatinine ratio, can provide further insight into kidney function and damage. It is essential to regularly monitor these parameters, especially in patients with risk factors such as diabetes, hypertension, or a family history of kidney disease, to detect kidney failure early and initiate appropriate management.
From the Research
Laboratory Tests for Kidney Failure
The following laboratory tests are used to indicate kidney failure:
- Serum creatinine concentration [ 2, 3, 4, 5 ]
- Estimated glomerular filtration rate (eGFR) [ 2, 3, 5, 6 ]
- Urinary albumin-to-creatinine ratio [ 2 ]
- Quantitative proteinuria [ 6 ]
- Phosphorus and parathyroid hormone (PTH) monitoring [ 6 ]
Interpretation of Laboratory Results
The interpretation of laboratory results is crucial in diagnosing kidney failure. For example:
- A serum creatinine level of greater than 1.7 mg/dL (>150 micro mol/L) has a sensitivity of 12.6% and a specificity of 99.9% for the detection of renal failure [ 4 ]
- An eGFR of less than 60 mL/min/1.73 m2 indicates kidney failure [ 2, 6 ]
- A rise in serum creatinine level of up to 30% that stabilizes within the first 2 months of ACEI therapy is associated with long-term preservation of renal function [ 3, 5 ]
Surveillance and Monitoring
Regular surveillance and monitoring of laboratory tests are essential for patients with kidney failure, including: