Comparing glomerular filtration rate equations and the impact of different creatinine assays on the assessment of renal function in cancer patients.

Background: Equations to estimate glomerular filtration rate based on serum creatinine are commonly used in cancer patients to assess renal function. However, there is uncertainty regarding which equation is most appropriate for this population and the impact of different creatinine assays.

Methods: Measured isotopic glomerular filtration rate results from 120 oncology patients were used to evaluate and compare all four versions of the Wright equation, Cockcroft and Gault, Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration and the Janowitz and Williams formula; using eight different creatinine assays (five Jaffe, three enzymatic).

The implementation of a system for managing analytical quality in networked laboratories.

Background: In a network of laboratories analytical variability between instruments, even of the same type, may exist for reasons beyond the control of laboratory staff. Controlling variability is a prerequisite for the application of shared reference ranges and for ensuring the transferability of patient test results. Controlling variability requires a robust, non-conventional quality system to detect poor performance of analysers that are geographically distant.