Hyperphosphatemia, Hyperphosphaturia and Hypocalcemia in Acute Lymphoblastic Leukemia

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Abstract
Four children with acute lymphoblastic leukemia received a controlled dietary intake of protein, calcium and phosphorus to study prospectively the changes in the serum and urinary calcium and phosphorus values, which occur during therapy of the disease. Two 12-hour urine collections were obtained daily for determinations of phosphorus, calcium, uric acid and creatinine. Serum creatinine, urea nitrogen, calcium, phosphorus and uric acid were measured midway through each collection. Hyperphosphatemia (values of 5.7 to 9.4 mg per 100 ml), hypocalcemia (values of 6.6 to 8.3 mg per 100 ml) and marked hyperphosphaturia were observed within 24 to 48 hours of the initiation of chemotherapy. The tubular reabsorption of phosphorus decreased to levels that were 20 to 70 per cent of pretreatment base-line values. Symptomatic hypocalcemia is most common in patients with exceptionally high peripheral lymphoblast counts and some degree of renal insufficiency. These events may be caused by the increased endogenous phosphorus load resulting from the destruction of lymphoblasts, in the same fashion that purine release leads to hyperuricemia. (N Engl J Med 289:1335–1340, 1973)