The glomerular filtration rate (GFR) is a measure of how well the kidneys filter blood. It indicates the volume of blood that passes through the glomeruli, tiny structures in the kidneys, each minute. A normal GFR is essential for maintaining the body's balance of fluids and electrolytes. GFR is often used to assess kidney function and diagnose conditions like chronic kidney disease. It can be estimated using blood tests that measure levels of creatinine, a waste product. Monitoring GFR helps healthcare providers determine the severity of kidney issues and guide treatment decisions.