Methaemalbumin and serum haptoglobin levels in the assessment of intravascular haemolysis

Abstract

The availability of a large group of patients who had had artificial heart valves inserted over previous years enabled a critical examination and comparison of the measurement of methaemalbumin and serum haptoglobin in the detection of intravascular haemolysis. Blood was taken from fasting patients to minimize serum turbidity due to lipaemia. The blood was carefully taken by an experienced operator to avoid red cell damage and haemoglobin release in vitro , and the red cells and serum were separated as soon as possible. The haptoglobin levels were measured using a modification of the method of Ratcliff and Hardwicke. Two hundred duplicate estimations were performed on 100 male and 100 female normal controls. The normal range was 45.0-170.0 mg/100 ml and there was no significant differences between the sexes. Of the 27 patients with artificial valves, only 4 showed haptoglobin levels in the normal range. It was shown that lipaemic serum gave a falsely high reading, that haemolysis in vitro did not affect the result, and that a high serum bilirubin level caused a poor resolution of the haemoglobin/haptoglobin peak. Methaemalbumin was estimated in the same specimens using 2 different methods. One utilized the Hartridge reversion spectroscope and the other a Shimadzu scanning spectrophotometer. Using the spectrophotometer 6 negative results were recorded and there was good agreement between this method and the estimation of serum haptoglobin in the detection of intravascular haemolysis. In one case disagreement was considered to be due to an elevated haptoglobin level in association with Q-fever endocarditis.