Hospital-associated hyponatremia

An 18-year-old woman with cystic fibrosis was admitted to the hospital for evaluation of shortness of breath and a productive cough of one week duration and Laboratory data revealed normal white blood cell count and large numbers of Staphylococcus aureus and pseudomonas spe-

Abstract

Patient 1. An 18-year-old woman with cystic fibrosis was admitted to the hospital for evaluation of shortness of breath and a productive cough of one week duration. She had required hospitalization for pneumonia at ages 12 and 16 and again 6 months prior to the present admission. Fat malabsorption (30—50 g/day) and an elevated sweat chloride concentration had been documented. Medications at the time of admission included trimethoprim-sulfamethoxazole, one tablet twice daily; theophylline; and a pancreatic enzyme preparation. Weight was 37 kg; temperature, 37°C; respiratory rate, 20/mm; blood pressure, 104/76 mm Hg supine and 102/64 mm Hg upright. Pertinent physical findings included: clubbing of finger nails; diffuse coarse rales, rhonchi, and wheezes throughout the chest; and moist mucous membranes. There was no cyanosis or edema and skin turgor was normal. Laboratory data revealed: hemoglobin, 12,5 g/dl; white blood cell count, l5,000/mm (80% neutrophils, 4% bands, 13% lymphocytes); normal prothrombin time and Pri'; albumin, 2.7 g/dl; BUN and creatinine, 6 and 0.5 mg/dl, respectively; and glucose, 96 mgldl. Serum electrolytes were: sodium, 136; potassium, 3.5; chloride, 96; and total CO2. 28 mEq/liter. Arterial blood gas measurements, obtained while the patient was breathing 4 liters of oxygen by nasal prongs, revealed a P02 of 67 mm Hg, a PCO2 of 40 mm Hg, and a pH of 7.50. Chest x-ray disclosed bibasilar and right middle lobe infiltrates. Sputum culture grew large numbers of Staphylococcus aureus and pseudomonas spe-