Abnormal results indicate Paroxysmal cold hemoglobinuria (PCH), a disorder that results from the presence of an antibody to the so-called "P-antigen complex" on red blood cells. This antibody is also referred to as a Donath-Landsteiner antibody. Reduced temperatures somehow cause the antibody to bind to the P-antigen on red blood cells. This causes destruction of red blood cells (complement-mediated hemolysis); and hemoglobin (a protein in red blood cells) is excreted in the urine. (See complement.)

PCH is an acquired syndrome. The appearance of the antibody has been associated with viral infections (for example, measles and mumps) and with syphilis. However, in rare cases there is no apparent disease-related association.