HDCN Article Review/Hyperlink

Follin SL, Mueller BA, Scott MK, Carfagna MA, Kraus MA

Falsely elevated serum vancomycin concentration in hemodialysis patients

Am J Kidney Dis (Jan) 27:67-74 1996

The elimination kinetics of vancomycin are variable in patients with renal failure. Elimination by residual renal function, assay variability, and changes in volume of distribution contribute to the difficulty in achieving desired peak and trough levels. These investigators measured vancomycin levels in eight hemodialysis patients. They compared the levels measured by fluorescence polarization immunoassay (FPIA) to those measured by enzyme multiplied immunoassay (EMIT). They found that FPIA levels were consistently higher than those measured using EMIT. The investigators conclude that FPIA overestimates vancomycin levels because the polyclonal antibody used in the FPIA assay also measures microbiologically inactive crystalline degradation products, while the monoclonal antibody used in the EMIT assay does not.

Comment: This paper emphasizes the need for accurate measurements of antibiotic blood levels to avoid ineffective therapy or drug toxicity. However, the investigators compared two indirect measurements of vancomycin blood levels. Their conclusion that FPIA measured blood levels are less accurate than EMIT measured levels would be substantially strengthened had they included comparisons with blood levels measured using high-performance liquid chromatography (HPLC) and microbiological assay. The questions raised by this investigation are important and worthy of more definitive answers. (George R. Aronoff, M.D.)