This lady’s blood film shows red cell agglutination at room temperature which resolves with sample
warming to 37 degrees Celsius. There is also polychromasia with spherocytosis. Her
thrombocytopenia is mild but genuine with no platelets clumps.
You suspect this lady has haemolytic anaemia secondary to cold haemagglutinin disease (CHAD) and
arrange for her to be admitted to your hospital’s urgent care centre. You arrange further tests which
support your diagnosis, including:
Direct antiglobulin (Coombs) test: positive (anti-C3d +++)
Bilirubin: 26 umol/L
LDH: 740 U/L
Reticulocytes: 188 x109/L (5.8%)
A CT chest/abdomen/pelvis is only significant for moderate splenomegaly (17cm) with no associated
What do you think could be the cause of this lady’s CHAD, and how would you investigate?