Assessment of renal function and progression of disease

Detection of early renal dysfunction remains a difficult problem because creatinine levels often do not become abnormal until glomerular filtration rate is severely reduced. Creatol, which also accumulates in renal failure, has been suggested as an alternative to creatinine. To measure glomerular filtration rate, a number of simplified techniques have been suggested; for the most part, however, they have not been validated in patients with severe chronic renal failure. Glomerular filtration rate can be estimated with fair precision from serum creatinine concentration with the use of improved equations, provided that the serum creatinine level is greater than 2 mg/dL. The use of cimetidine to reduce the discrepancy between creatinine clearance and glomerular filtration rate does not seem justifiable. In diabetic nephropathy, sequential biopsies may be preferable to sequential determinations of glomerular filtration rate for follow-up of patients with this disease.