Marked hypophosphatemia associated with acute myelomonocytic leukemia. Indirect evidence of phosphorus uptake by leukemic cells.

A 51-year-man was seen with the diagnosis of acute myelomonocytic leukemia. The WBC count was 380,000/microL at presentation. The serum phosphorus concentration was 0.4 mg/dL and 0.2 mg/dL prior to any phosphorus replacement. Urinary phosphorus excretion was too low to be measured. The patient did not demonstrate any of the usual causes of profound hypophosphatemia with hypophosphaturia. The parathyroid glands were normal at necropsy. Reasons for believing the profound hypophosphatemia was due to phosphorus uptake by the leukemic cells are discussed.