Hyperparathyroidism-an unusual case.

A case of primary hyperparathyroidism is described that presented unusual features. The patient had been treated previously for squamous cell carcinoma of the lung and therefore it was necessary to exclude ectopic hyperparathyroidism. The results of the tests generally used to distinguish primary from ectopic hyperparathyroidism-the serum chloride level, the serum calcium response to cortisone suppression and the absence of residual or recurrent tumour-suggested that the patient did have the primary form of the disorder. Exploration of the neck revealed no parathyroid tumour or hyperplasia, and the mediastinal parathyroid adenoma was localized only by determination of parathyroid hormone in the venous drainage from the neck and mediastinum.