L-Arginine, ADMA, SDMA, creatinine, MDRD formula: detour to renal function testing.

We report the case of a 50-year-old woman in whom a laboratory work-up for a suspected L-arginine deficiency and the concomitant determination of elevated symmetrical dimethylarginine (SDMA) led to a diagnosis of chronic kidney disease. This diagnosis had been missed due to the '';normal'' serum creatinine. This case illustrates that patients and physicians, while perusing non-evidence-based treatment strategies, such as L-arginine supplementation, fail to recognize the importance of evidence-based medicine, such as renal function testing. It also supports the notion that routine estimation of glomerular filtration rate should be mandatory in every patient for whom a serum creatinine test is ordered.