January 5, 2009

CAP Survey: Seventy percent of clinical labs in U.S. reporting eGFR

The number of clinical laboratories in the United States that report estimated glomerular filtration rate (eGFR) is now 70% according to recent data from the College of American Pathologists. These data are derived from laboratories that participate in the College's proficiency testing program and so tend to be larger labs such a reference labs and hospital labs. This is good news. Chronic kidney disease is a major public health problem and we will be looking at this in more detail later in the course.

There are two ways to screen for CKD: estimated glomerular filtration rate based on serum or plasma creatinine as calculated using the Modification of Diet in Renal Disease (MDRD) formula, and detection of albumin loss in urine. We will be looking at the specifics of these approaches when we come to renal function testing in a few weeks. The point to be understood now is that clinical labs are asked, where feasible, to routinely report the eGFR when creatinine is ordered. The idea of a reference range, which we'll be discussing this week, has to be re-examined for plasma creatinine because levels are so dependent on age, gender, and racial background. The MDRD equation is a way to move beyond the simple idea of a reference range (a one-size-fits-all approach) to getting a value that is appropriate to the individual patient and identifying those who have early impairment of renal function and who could benefit from therapeutic intervention.