Relationship between lactate dehydrogenase response, eculizumab serum levels, and the thermal amplitude of the cold agglutinin. Difference in the lactate dehydrogenase level between the first and the last day of treatment (upper) and median eculizumab trough level between week 4 and week 26 of the treatment phase (lower) in relation to the thermal amplitude of the cold agglutinin in 12 patients with chronic CAD. Patients with or without a lactate dehydrogenase decrease ≥250 U/L are represented by solid or open circles, respectively.