PAROXYSMAL COLD HEMOGLOBINURIA - A rare blood disorder caused by antibodies which destroy red blood cells upon exposure to the cold. The antibodies are formed against a specific blood group and are triggered by the cold. The cause is unknown but the disease has been associated with syphilis and some viral infections. Serum hemoglobin and urine hemoglobin are increased during the attacks. The disease is chronic and treatment is difficult. Some cases resolve spontaneously without treatment.