Measurements of serum gentamicin concentrations by a biological method, fluorescence polarization immunoassay and enzyme multiplied immunoassay.

Serum gentamicin levels were assayed in patients receiving the aminoglycoside to determine dosage adjustments. The accuracy and reproducibility of three methods were compared; bioassay, enzyme multiplied immunoassay (Syva EMIT) and fluorescence polarisation immunoassay (Abbott TDx). Each assay method offered acceptable precision. The bioassay method correlated well with both the enzyme multiplied immunoassay and the fluorescence polarisation immunoassay (correlation coefficients 0.854 and 0.937, respectively). The automated methods provide results within 15 min and are not influenced by combinations of antibiotics, hence they are the methods of choice for aminoglycoside determinations.