[Pituitary tumor syndrome and hyperprolactinemia in peripheral hypothyroidism]

We studied 7 women with primary hypothyroidism who were suspected to harbor a prolactinoma on the basis of a pituitary gland enlargement associated with hyperprolactinemia. The diagnosis of prolactinoma was confirmed in 1 case only, which was treated surgically. In the remaining 6 patients the serum prolactin levels fell to normal on thyroxine replacement therapy and reduction in size of the pituitary gland was demonstrated by neuroradiological imaging in the 3 documented cases. This study underlines the fact that hyperprolactinemia associated with pituitary hyperplasia is secondary to hypothyroidism and that thyroid function tests should be obtained in all hyperprolactinemic patients even those with pituitary enlargement.