October 2011

The CAP has 30 official liaisons to various organizations who attend scientific meetings or designate others to do so. They report to the Standards Committee, which reports to the Council on Scientific Affairs. We publish periodically bits of what the CAP’s outbound liaisons hear and see in their liaison roles.

eGFR goes global

John H. Eckfeldt, MD, PhD

Considerable effort has been made over the past six to eight years to have clinical laboratories report estimated glomerular filtration rate (eGFR) based on serum creatinine. The goal is to detect chronic kidney disease early, before the onset of end-stage renal disease, so that measures may be taken to stop or at least slow the decline in the patient’s renal function. In the United States, this effort, spearheaded by the National Kidney Disease Education Program, appears to have been successful, with a recent CAP Survey showing that more than 80 percent of clinical laboratories surveyed now report an eGFR when a serum creatinine is measured.

Accurate eGFR reporting based on serum creatinine required standardization of creatinine methods, and recent data from the CAP’s accuracy-based serum creatinine Survey shows that variability across laboratories in the U.S. has dropped to less than half of what it was about six years ago. Authorities are less certain about creatinine standardization in other parts of the world, however, and the increase in chronic kidney disease and ESRD is an international problem, not limited to Western or developed countries. The need for international collaboration in improving early detection of chronic kidney disease has sparked the formation of a collaborative CKD Task Force by the World Association of Societies of Pathology and Laboratory Medicine (WASPaLM) and the International Federation for Clinical Chemistry (IFCC).

The most recent meeting of the WASPaLM/IFCC CKD Task Force took place in May in Berlin, Germany. The major topics discussed were ways to aid countries in improving the accuracy of their serum creatinine measurements in a cost-effective manner, and the promotion of clinical reporting of eGFR worldwide. A Web-based survey has discovered fairly successful national efforts in some countries (for example, Uruguay and India). However, in many parts of the world, these efforts are not as well coordinated as they might be. Some countries, especially in Scandinavia, are calculating eGFR using biomarkers such as serum cystatin C in addition to creatinine. Although a high-level reference material for cystatin C is now available from the Institute of Reference Materials and Measurements in Geel, Belgium, the CKD Task Force is still focusing on creatinine-based eGFR reporting and ways to improve its accuracy and use.

As the international community embraces eGFR reporting based on serum biomarkers, it will need to address another area of uncertainty. Because eGFR calculation requires patient-specific demographic information (for example, age, gender, and racial/ethnic group), the influence of race and ethnicity on creatinine excretion will need attention. Unfortunately, gathering information in this area has been difficult. While part of the variability stems from differences in muscle mass among people with different genetic backgrounds, there are also environmental influences such as diet. The amount of meat in the diet is a key factor since the creatine in muscle tissue in animals is readily converted with cooking to creatinine.

WASPaLM was initially formed in 1947 as the International Society of Clinical Pathology to aid the coordination of pathology societies worldwide. The society’s name was changed several times; WASPaLM was adopted in 1999 to indicate more clearly that the organization’s scope covers both anatomic and clinical pathology.