[Serum cystatin C: a practical alternative for renal function evaluation?].

Glomerular filtration rate is the main marker of renal function in healthy individuals and patients. Despite incontestable advances in medicine, it is still difficult to define precisely this test in clinical practice. Early markers of renal lesion are important, because glomerular filtration rate usually decreases before the first chronic renal failure symptoms or signs appear. Cystatin C has been pointed as an alternative, but it was not tested in many diseases. Advantages and disadvantages of this marker are discussed. Although serum cystatin C determination is increasingly being used in clinical practice worldwide, its limitations as well as the conditions its use is in fact indicated are not adequately established; on the other hand serum creatinine (and creatinine clearance) is an easily available and low cost laboratory marker with well-known limitations that can be used routinely in the assessment of renal function.