Experience with the cumulative integral method for measurement of glomerular filtration rate.

The glomerular filtration rate (GFR) was estimated using (125)I-iothalamate by the cumulative integral method in 95 subjects - 16 normal subjects and 79 patients with suspected or proved renal disease. This method is accurate, simple to perform and theoretically sound. It minimizes errors due to transit time and bladder storage. The normal range of GFR was determined to be 71 +/- 10 (two standard deviations) ml/min/m(2). In 66 patients serum creatinine levels were compared with the GFR value expressed per square metre. For any given serum creatinine level there is a wide range of GFR values. A serum creatinine value in the normal range, i.e. between 0.7 and 1.3 mg/dl, cannot be used to predict the patient's GFR. The micro blood sampling technique makes this method particularly useful in infants.