The correlation of cold agglutinin titrations in saline and albumin with haemolytic anaemia.

Cold agglutinin syndrome (CAS) is usually associated with IgM cold agglutinins with titres exceeding 1000 at 4 degrees C and a thermal amplitude of 30-32 degrees C. Occasionally patients are encountered who although having clinical and laboratory findings compatible with CAS do not have the characteristic serological findings. Thirty-two patients with a positive direct antiglobulin test due to complement sensitization were studied. Thirty-one of these patients had cold agglutinin titres greater than 64. Twenty-eight had haemolytic anaemia, including one patient with a cold agglutinin titre of only 8 against saline-suspended red cells. 53.6% of sera from patients with haemolytic anaemia reacted at 30 degrees C and 7.1% at 37 degrees C when albumin was not present, whereas in the presence of albumin all of the sera reacted at 30 degrees C and 67.9% reacted at 37 degrees C. None of the four patients without haemolytic anaemia reacted at 30 degrees C or 37 degrees C in the presence of albumin, even though one serum reacted to a titre of 1280 at 4 degrees C. Cold agglutinin titres and thermal amplitudes in the presence of bovine albumin were found to correlate better with haemolytic anaemia than reactions without albumin. If bovine albumin is utilized in compatibility testing, multiple cold autoabsorptions may be necessary before alloantibody activity at 37 degrees C can be excluded.