[Key note comment on the determination of glomerular filtration rate]

Glomerular filtration rate (GRF) is the most fundamental renal function. Determination of GFR is the most important examination in clinical nephrology. Cin is accepted as the gold standard of GFR, but, continuous infusion and the determination method of inulin (method of anthrone) are very troublesome. Interference of glucose in the serum and urine of patients with diabetes mellitus on the determination of inulin should be avoided. Ccr is widely used in the clinical field. Recently, the dynamics of creatinine in the body have been clarified. Variation of pool, generation rate, extrarenal excretion and tubular excretion of creatinine are found to change daily in the patient. Additionally, classical Jaffé's reaction involves non creatinine chromogen particularly in the serum. Though Jaffé's reaction with kinetic analysis improves the reliability of this reaction, the result is still unsatisfactory. There are several methods of enzyme assay are now using an autoanalyser, but, if we use many enzymes and reagents, the reliability of this method could not exceed that of Jaffé's method. Recently, HPLC is recommended as the standard method. 24-hr urine collection is also troublesome in the measurement of Ccr. I have found a good correlation between the estimated Ccr using Cockcroft and Gault's formula and Cin. Such prediction using serum creatinine concentration and few parameters should be developed. Radiolabelled agents have been widely used for the determination of GFR. However, in Japan, the methods of clearance of non radiolabelled contrast agents should be developed. Furthermore, a physical determination of GFR is necessary. In this workshop, these issues will be discussed by each speaker.