Syndrome of inappropriate antidiuretic hormone secretion due to treatment of lung cancer with cisplatin.

CASE 1 A 61 year old woman presented with a two day history of pleuritic chest pain and a productive cough. Material obtained by biopsy of an endoscopically visible bronchial tumour showed appearances of small cell undifferentiated carcinoma. Staging procedures suggested that this was confined to the thorax. Haematological and biochemical indices were normal. She commenced treatment with two cycles of intravenous vincristine 1*2 mg/m2, adriamycin 40 mg/i2, and cyclophosphamide 760 mg/i2, alternating with two cycles of intravenous cisplatin 100 mg/i2 and etoposide 110 mg/i2, at intervals of three weeks. Having completed the first two cycles uneventfully she was readmitted for her third cycle and before starting the cisplatin infusion underwent a period of prehydration with mannitol diuresis as described by Hayes et al 1977.' The results of electrolyte and osmolality determinations before and after treatment are detailed in the table. Before treatment her blood pressure was 150/90 mm Hg and this did not alter appreciably during the period of fluid volume overload. The syndrome of inappropriate antidiuretic hormone secretion was diagnosed and fluid restriction was imposed, which resulted in the return of her serum electrolytes to normal within 10 days. Chemotherapy was subsequently continued without cisplatin and there were no further episodes of electrolyte disturbance during the course of her illness, although she failed to respond to chemotherapy and died six months after the onset of symptoms.