Acute kidney injury: time to shift from creatinine to the estimated glomerular filtration rate?

Acute kidney injury (AKI) is a complex disorder for which currently there is no accepted definition. Although several groups are working on developing and validating biomarkers of kidney injury and the glomerular filtration rate (GFR), the proposed diagnostic criteria from the Acute Kidney Injury Network are based on an absolute increase in serum creatinine ≥0.3 mg/dl (≥26.4 μmol/l), a percentage increase in serum creatinine ≥50% (1.5-fold from baseline), or a reduction in urine output (documented oliguria <0.5 ml/kg per hour for more than 6 hours) [1]. A recent report from the Laboratory Working Group of the National Kidney Disease Education Program, however, recommends that serum creatinine alone should not be used to assess the GFR or to detect the presence of kidney disease because it is affected by the GFR and by factors independent of the GFR, including age, sex, race, body size, diet, certain drugs, and laboratory analytical methods [2]. Rather, the Working Group suggests implementing the estimated GFR using the Modification of Diet in Renal Disease (MDRD) study [2]. In analogy with chronic kidney disease, implementation of the MDRD equation would probably grant more clinically useful information to assess AKI. Letter Acute kidney injury: time to shift from creatinine to the estimated glomerular filtration rate? Giuseppe Lippi and Gian Cesare Guidi