PITUITARY ENLARGEMENT AND HYPERPROLACTINEMIA IN PRIMARY HYPOTHYROIDISM

We studied 7 women with primary hypothyroidism who were suspected to h arbor a prolactinoma on the basis of a pituitary gland enlargement ass ociated with hyperprolactinemia. The diagnosis of prolactinoma was con firmed in 1 case only, which was treated surgically. In the remaining 6 patients the serum prolactin levels fell to normal on thyroxine repl acement therapy and reduction in size of the pituitary gland was demon strated by neuroradiological imaging in the 3 documented cases. This s tudy underlines the fact that hyperprolactinemia associated with pitui tary hyperplasia is secondary to hypothyroidism and that thyroid funct ion tests should be obtained in all hyperprolactinemic patients even t hose with pituitary enlargement.