Severe Hypophosphatemia in Hospitalized Patients

Severe hypophosphatemia (serum phosphorus less than or equal to 0.48 mmol/L less than or equal to 1.5 mg/dL) was found in 120 patients admitted to a major university hospital, during a period of 16 months. Fifty-one patients (42.5%) developed hypophosphatemia postoperatively. Medications known to precipitate hypophosphatemia were a causative factor in 82% of the patients, with glucose administered intravenously, antacids, diuretics, and steroids being the most common agents associated with profound hypophosphatemia. Gram-negative septicemia was observed in 16 patients, and it was the second most common cause of severe hypophosphatemia. The mortality rate was 20% in patients with a serum phosphorus concentration between 0.36 and 0.48 mmol/L (1.1 and 1.5 mg/dL) (group A) and 30% in patients with a serum phosphorus concentration of less than or equal to 0.32 mmol/L (less than or equal to 1.0 mg/dL) (group B). The cause of death and its temporal association with the lowest observed values of phosphorus concentration indicate that severe hypophosphatemia might be a contributory factor to mortality. Our data indicate that severe hypophosphatemia in hospitalized patients is the result of a combination of factors. Surgery, followed by a period of fasting with intravenous administration of glucose, and gram-negative septicemia are the most common causes.