A woman with isolated prolactin deficiency

It is well established that hyperprolactinemia due to either pituitary prol actinoma or hypothalamic derangement interferes with normal cyclic feed bac k mechanism. However, there are reports that prolactin (PRL) oversuppressio n to below normal levels causes the impairment of progesterone synthesis in normal cycling women (1, 2). It appears that a certain plasma level of PRL is required for progesterone synthesis to proceed normally. However, this concept is based on circumstances where PRL deficiency was surgically or me dically induced. Thus, the clinical significance of hypoprolactinemia remai ns to be elucidated. We report a very rare case of isolated PRL deficiency, and discuss the relationship between hypoprolactinemia and reproductive fu nction such as lactogenesis and ovarian function.