Which factor is critical when using the Cockcroft-Gault formula for calculating eGFR?

The Cockcroft-Gault formula for estimating the glomerular filtration rate (eGFR) is primarily influenced by the age of the patient, as the formula calculates renal function based on several key parameters. Age is crucial because kidney function generally declines with age, and this decline is factored into the equation to provide a more accurate estimate of eGFR. As individuals age, their muscle mass typically decreases, which can affect creatinine production.

Incorporating age adjusts the eGFR to reflect the natural physiological changes that occur over time, thereby enhancing the reliability of the estimation in older adults. While other factors, like weight and gender, are also included in the formula, the influence of age is a significant component that emphasizes how renal function can vary across different age groups.