Creatinine, a substance found in the bloodstream, undergoes a process called clearance, which refers to its removal from the plasma and subsequent excretion in the urine. By observing the disparity between creatinine levels in the plasma and urine, we can gain insights into the rate at which the kidneys filter blood, known as the glomerular filtration rate (GFR). Notably, due to the absence of reabsorption of creatinine in the renal tubules, its clearance serves as a valuable measure for estimating GFR.