Mixed TSH- and HGH-secreting pituitary adenoma.

A man aged 36 was found to have an invasive pituitary adenoma with evolutive acromegaly and hyperthyroidism and a high serum level of HGH and TSH, suggesting a tumoral production of HGH and TSH. The serum concentration of HGH was above 180 ng/ml; there was also an inappropriately high serum level of TSH, which failed to decrease following the triiodothyronine suppression test and did not increase after TRH (0.4 mg i.v.). In the tumoral tissue removed during pituitary surgery, the concentration of TSH was 1,267.2 microU/g and that of HGH was 1,158.6 micrograms/g, showing that the pituitary adenoma secreted both TSH and HGH.