The big picture: Estimated glomerular filtration rate (eGFR) is a critical measure that indicates how well the kidneys are filtering blood and removing waste. A high eGFR is indicative of healthy kidney function, while a low or declining eGFR may point to potential kidney impairment or disease.

A benchmark for kidney function: Glomerular filtration rate (GFR) stands as the gold standard for assessing kidney function. Within each kidney, a vast network of nephrons performs the essential task of blood filtration. GFR reflects the collective filtration efficiency of these numerous nephrons, thus serving as a comprehensive indicator of kidney health.

Estimating GFR: While direct measurement of GFR presents challenges, it can be estimated effectively based on age, sex and how well your kidneys filter two agents produced by the body:

Creatinine: This muscle metabolism byproduct is a conventional marker for kidney filtration, reflecting waste removal efficiency.
Cystatin C: This protein plays a vital role in regulating cell protein breakdown, offering an alternative and more sensitive measure of kidney function.

Early kidney disease detector: eGFR is instrumental in early kidney disease detection given kidney disease often progresses silently without symptoms. Regular eGFR monitoring allows for timely identification and management of kidney health issues.

Normal GFR and kidney disease risk: A normal GFR in healthy, young individuals often exceeds 90 mL/min/1.73 m². A GFR persistently below 60 mL/min/1.73m² suggests increased risks of chronic kidney disease and its complications, including cardiovascular issues.

Kidney function over time: Kidney function naturally declines with age. A young adult should ideally have an eGFR above 90, but this can be reduced by 6-10 units per decade after the age of 50. This gradual decline necessitates a proactive approach to kidney health, emphasizing the need for regular monitoring and lifestyle adjustments to preserve kidney function.

The stages of kidney disease: Chronic kidney disease is categorized into five stages, with Stage 1 starting at a GFR above 90 but possibly indicating kidney damage if protein is found in the urine. As the GFR decreases, the stages advance, with each stage presenting increasing levels of concern and requiring more intensive management.

Improving eGFR: To maintain or improve kidney function and eGFR, it's vital to manage underlying health issues that can cause its decline:

Control blood pressure: High blood pressure is a significant risk factor for chronic kidney disease. Regular monitoring and appropriate management, including medication and lifestyle changes, are essential.

Manage diabetes: Effective control of blood sugar levels can help prevent or delay the progression of chronic kidney disease in diabetic patients.