Estimated Glomerular Filtration Rate
Introduction
The Estimated Glomerular Filtration Rate (eGFR) is a test used to check how well the kidneys are working. Specifically, it estimates the amount of blood that passes through the glomeruli (tiny filters in the kidneys that filter waste from the blood) each minute.
Calculation
The eGFR is calculated using a formula that includes the patient's age, gender, and blood creatinine level. The most commonly used equation for estimating GFR from serum creatinine is the Modification of Diet in Renal Disease (MDRD) Study equation. The MDRD Study equation has been further refined and is now often replaced by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.
Interpretation
The eGFR is used in the diagnosis of kidney disease. A value of 60 or higher is in the normal range. A value less than 60 may indicate kidney disease. A value of 15 or less is described as kidney failure.
Limitations
The eGFR has limitations. It is less accurate for people at the extremes of body size, for those with unusual muscle mass, and for those with rapidly changing kidney function. It is also less accurate for people who are very young or very old.
Clinical Use
In clinical practice, the eGFR is used to monitor the progression of kidney disease, to guide dosing of medications, and to assess the risk of developing complications from kidney disease.
Conclusion
The eGFR is a crucial tool in the diagnosis and management of kidney disease. Despite its limitations, it is widely used in clinical practice due to its simplicity and cost-effectiveness.