A regional survey of serum creatinine measurement methods and estimated glomerular filtration rate reporting

Only limited data are available on the diffusion of isotope dilution mass spectrometry (IDMS)-traceable methods used for serum creatinine measurement and on estimated glomerular filtration rate (eGFR) reporting.

A questionnaire was addressed to accredited laboratories in Lombardy, Italy, including the following issues: method of creatinine measurement, instrument model, IDMS calibration traceability, reference intervals reported by sex and age, eGFR reporting, eGFR formula used and information about the eGFR value reported in patient records. A parallel questionnaire was addressed to nephrology centers and included the following: knowledge of methods for serum creatinine measurement in their center, usefulness of eGRF reporting and opinions on the need for educational initiatives.

Seventy-two percent of 72 laboratories and 89% of 47 nephrology centers responded to the questionnaires. Among the methods used for serum creatinine measurement, 87% were IDMS traceable and 30% were enzymatic. Reference intervals were differentiated by sex and by age in 90% and 42%, respectively. Laboratories reported eGFR in 35% and only when requested in 13%. eGFR was calculated by the Modification of Diet in Renal Disease (MDRD) Study and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in 88% and 12% of laboratories, respectively, and reporting was accompanied by information on the interpretation of values in 62%. Among nephrologists, 64% thought eGFR reporting useful, 29% were concerned with an excess of unnecessary requests for consultations and 95% expressed a favorable opinion of educational initiatives.

Our survey highlights the need for further improvement in serum creatinine measurement and reporting, and for coordinated interventions involving all major stakeholders.