RESUMEN
BACKGROUND: Plasma hemoglobin has usually been determined by the spectrophotometric method of Harboe. This method is known to show interference by bilirubin and turbidity, although the method is easy. In order to correct the spurious increase of plasma hemoglobin concentration caused by hyper-bilirubinemia, we compared plasma hemoglobin assays by using various spectrophotometry methods and tried to select the method of minimal interference. METHODS: We performed five plasma hemoglobin assays based on spectrophotometry (Harboe, Noe, Kahn, Fairbanks 1, and Fairbanks 2) and three bilirubin assays (Fairbanks 1, Fairbanks 2, and bilirubin oxidase) on 100 patients without hemolysis and lipemia. RESULTS: The method of Kahn, et al. and the method 2 of Fairbanks, et al. of the plasma hemoglobinassay seemed to minimally interfere with the bilirubin. Only plasma oxyhemoglobin was measured by the method of Kahn, et al .; on the other hand, plasma hemoglobin and bilirubin could be measured one at a time by the method 2 of Fairbanks, et al. Method 1 of Fairbanks, et al. seemed to interfere extremely with bilirubin. CONCLUSIONS: Method 2 of Fairbanks, et al. is the first choice for the plasma hemoglobin assay considering the interference with bilirubin.