Since creatinine is virtually exclusively filtered at the kidney (apart from that which is produced by the kidney), it is possible to monitor creatinine clearance from the blood as a function of glomerular filtration rate, particularly before the administration of nephrotoxic medications. People who have one healthy kidney and one defective kidney typically have normal creatinine clearance rates because the healthy kidney will raise its rate of filtration to make up for the faulty kidney. A number of medications, including cephalosporins, aminoglycosides, cimetidine, and cisplatin, might lower the creatinine clearance measurement. Diuretics can improve the outcome.