Simple spectrophotometric determination of haptoglobin level in serum

Haptoglobin concentration was determined from the change caused in the absorption spectrum of hemoglobin due to binding with haptoglobin. Absorbance changed markedly near the Soret band, and a linear correlation could be observed between the extent of the absorbance change and the amount of free haptoglobin. The levels of serum haptoglobin measured by the present method correlated well with those determined by an electrophoretic or a peroxidase method. High concentrations (more than 10 mg/100 ml) of hematin gave positive interference in the measured haptoglobin level, whereas bilirubin and chylomicron showed low levels of interference. The proposed method could be used as a simple and reliable method for the determination of haptoglobin level in various types of sample.