Persistent hyponatraemia complicating fibrosing alveolitis.

PATIENT 1 A previously healthy 70-year-old housewife presented with dry cough and dyspnoea. She had finger clubbing, was dyspnoeic at rest, and had basal crackles. A chest radiograph showed bilateral reticulonodular shadowing. Spirometry showed a restrictive picture; transfer factor was very low at 3 55 ml/min/mm Hg (1 19 mmol min-' kPa-1). Pao2 at rest was 55 mm Hg (7 32 kPa), Paco, 40 mm Hg (5 32 kPa). Aspergillus precipitins were absent as were antinuclear antibodies. The result of a Mantoux test was negative. Sputum cytology showed no atypical cells. Cryptogenic fibrosing alveolitis was diagnosed, and the patient started taking oral prednisolone, 10 mg daily. She was admitted to hospital four months later with increasing dyspnoea, which had been treated by her general practitioner with a thiazide diuretic. Her physical findings and chest radiograph were unchanged, and she was