Alterations in serum prolactin heterogeneity by provocative tests in a patient with a pituitary tumour

The proportion of serum prolactin heterogeneity were investigated in a patient with a pituitary adenoma producing both prolactin and growth hormone. Glucose tolerance (GTT) and insulin tolerance (ITT) tests were performed alone and in combination with chlorpromazine both before and after hypophysectomy. Serum prolactin multiple forms were separated by Sephadex G-100 column chromatography at 3 degrees C. None of the provocative tests altered the already elevated serum prolactin either before (300 ng/ml) or after (100 ng/ml)hypophysectomy. Chlorpromazine or ITT did not alter the proportion of prolactin heterogeneity; GTT, whether in conjunction with chlorpromazine or alone and both before and after hypophysectomy, increased the proportions of the larger molecular species. In five tests in which the GTT was not performed the prolactin heterogeneity was as follows: 'void volume', 4.9%; 'big', 13.1%; 'little', 82.1%; in those experiments in which the GTT was performed the proportions of prolactin heterogeneity were: 'void volume', 13.5%, 'big', 19.2%; 'little', 67.3%.