Hyperprolactinemia unrelated to prolactinoma

Abstract Hyperprolactinemia, defined as prolactin levels above the upper limit of normal range, is the most frequent hypothalamus-pituitary dysfunction. Clinical symptoms of hyperprolactinemia in women include oligomenorrhea, infertility, and galactorrhea, while in men the condition may lead to hypogonadism, decreased libido, erectile dysfunction, infertility, gynecomastia, and, in rare instances, galactorrhea. In many patients, hyperprolactinemia results from the presence of prolactinoma, which is considered as the most common hormone-secreting pituitary tumors. However, transient or long-term hyperprolactinemia may also develop during different physiological situations or due to several diseases. It is also a frequent but often neglected side effect of many drugs, particularly of antipsychotics. Finally, hyperprolactinemia may be secondary to the predominance of high molecular mass circulating prolactin forms that have been postulated to represent complexes of prolactin and anti-prolactin immunoglobulins (macroprolactinemia). The cause of hyperprolactinemia determines its treatment. In this paper, we review the causes of hyperprolactinemia unrelated to prolactinoma, providing a differential diagnosis of this condition.