Mechanism of
hemolysis in postparturient hemoglobinemia was studied in 7 cows. Cows 1 to 5 had a history of hemoglobinemia at a previous calving, but hemoglobinemia did not occur during the present parturition. Cow 6, a daughter of cow 4, and cow 7 from another farm, developed postparturient hemoglobinemia and had
hemoglobinuria on days 20 and 21 and 10 to 17 after calving, respectively. During the time cows 6 and 7 had
hemoglobinuria, both cows had a marked decrease in serum inorganic
phosphorus, RBC
adenosine 5'-triphosphate (
ATP), and
reduced glutathione, and a significant (P less than 0.01) increase in
methemoglobin concentration. In cow 6, these changes were observed before the onset of
hemoglobinuria, indicating metabolic disorder of RBC. After
phosphate administration IV, serum inorganic
phosphorus was corrected, and RBC
ATP was increased above base-line value. During the time cows 6 and 7 had
hemoglobinuria, PCV,
hemoglobin concentration, and RBC count decreased progressively and reached nadir values, 40% to 50% of baseline values, on day 22 in cow 6 and on day 19 in cow 7. Cows 6 and 7 were anemic, even after serum inorganic
phosphorus and RBC
ATP values returned to acceptable values. Glycolytic disorder and depletion of
ATP, resulting from
phosphorus deficiency, appeared to be a primary and essential step leading to
hemolysis in postparturient hemoglobinemia in cows 6 and 7.