Hyponatremia in sickle cell disease. A renal salt-losing state.

Severe hyponatremia has been observed in three children with sickle cell disease, and mild hyponatremia was noted during 36% of random hospitalizations for sickle crisis secondary to vasoocclusion or infection. Serum and urinary electrolytes were therefore studied in such patients. Hyponatremia was found in 52% of patients hospitalized with pain and/or fever, even though they received large amounts of sodium intravenously. Urine sodium losses were high with frequent negative sodium balance and weight loss. When well, these patients did not demonstrate hyponatremia, although urinary salt losses appeared to be just as high, suggesting compensatory salt intake when the children are well. It is essential to monitor electrolytes and urinary losses to manage sickle crisis properly. Six to 11 mEq/kg/day of sodium is suggested as a usual need of these patients during crisis. Sickle cell disease patients have, in addition to the better known defect in concentration of urine, a functional defect in dilution of urine at least during periods of "crisis".