Abstract
A 42-year-old house wife was admitted with superior vena caval syndrome. The chest X-ray disclosed tumor masses in the right upper lobe associated with hilar and mediastinal lymphadenopathy.
Investigations revealed persistent hyponatremia, serum sodium level ranging between 112.3MEq/L-130MEq/L.
The patient was suspected to have pulmonary carcinoma associated with a syndrome of inappropriate secretion of ADH.
60Co theray on the mediastinum resulted in the disappearance of the superior vena caval syndrome. After superior vena caval syndrome disappeared, 60Co therapy on the primary tumor was started. 60Co therapy resulted in the improvement of hyponatremia, serum sodium increasing from 113MEq/L to 135MEq/L.
Plasma ADH activity, 5 hours after the water-load, was 8.0μU/ml.
These laboratory data and clinical course suggested the ectopic production of ADH by the pulmonary carcinoma.
Histological findings of the lungs at autopsy were interpreted as oat cell carcinoma. Ectopic ADH production was confirmed by the presence of ADH activity and electron microscopic findings of neurosecretory-like granules in the tumor tissue.
