Detection of Chronic Kidney Disease. Multidisciplinary document

Abstract

The increase of the prevalence of patients with Chronic Kidney Disease (CKD), has turn it into a worldwide problem of Public Health. Not only for its requirement of a kidney replaceable treatment, but also because the cardiovascular disease is now the main cause of death among these patients.  The plasma Creatinine dosage (Crp) is not always an early marker, due to the fact that its blood levels exceeds the highest limit of the reference range when the Glomerular Filtration Rate (GFR) decreases to half. The GFR measurement with exogenous markers is the best indicator to test the renal function (RF), although its use in the clinical practice is only for particular situations. The creatinine clearance (CC) may present mistakes caused by an inadequate urine collection. Moreover, it overestimates the GFR considering that the creatinine is not only excreted but it is also secreted at tubular level. The utilization of formulas associated to Crp is recommended by most of the scientific societies. The MDRD-4 equation has been adopted by consensus “eGFR (ml/min/1.73 m2)= 186 x (Crp) -1.154 x (age) -0.203 x (0.742 woman) x (1.212 black people)”. When the creatinine results are traceable to Isotope Dilution/Mass Spectrometry reference method, the initial factor is 175. This formula does not apply to pregnant women, hospitalized patients, people under 18 or older than 70 years old, amputees, etc. Given that the measurement of Crp is the biggest cause of error for the calculation of eGFR, the lab should validate the analytical procedure to determine creatinine. The Total Error should not exceed 8% in order not to produce an increase over 10% of the GFR estimation. For the detection of CKD it is recommended: 1) estimate the GFR using MDRD-4´s equation associated to Crp (Strength of Recommendation C); 2) report values over 60 ml/min/1.73 m2 only as “over 60” and values under 60 as the exact number obtained; 3) exclude in automatic calculation systems, situations that limit the use of the equation.