Diagnosis, misdiagnosis and management of hyperprolactinemia

Hyperprolactinemia is a commonly encountered disorder that suppresses both male and female gonadal function. The etiology includes pituitary tumors, hypothalamic or pituitary stalk lesions, drugs and hypothyroidism. In women, the hyperprolactinemic syndrome is characterized by menstrual disorders with or without galactorrhea, while men present with hypogonadism and related symptoms. Occasionally, a pituitary macroadenoma may be associated with pressure symptoms and/or hypopituitarism. Clinically, the most important cause of hyperprolactinemia is a prolactin-secreting pituitary adenoma. The majority of patients with prolactinomas are successfully managed medically with dopamine agonists such as cabergoline or bromocriptine. Misdiagnosis of hyperprolactinemia owing to immunoassay interference by a biologically minimally active form of prolactin termed macroprolactin is common in laboratory medicine. Alhough the etiology of macroprolactinemia is unclear, the condition is commonly associated with the presence of circulating antiprolactin antibodies. In the absence of specific testing, macroprolactin represents a diagnostic pitfall resulting in misdiagnosis and mismanagement of patients. This review examines the investigation and treatment of hyperprolactinemia in the broadened context of screening for macroprolactin and the consequences of failure to identify its presence.