Clinical manifestations of hyperprolactinemia

Hyperprolactinemia is also called hypersecretion, and this condition can be caused by a variety of reasons. The emergence of hyperprolactinemia can cause many harms to the body, such as accumulation of reproductive and nervous systems, including causing infertility and sexual dysfunction. The clinical manifestations of hyperprolactinemia include amenorrhea, lactation, frequent menstruation, and oligomenorrhea.

Causes

Under physiological conditions, inhibitory regulation is dominant in the regulation of prolactin. Any factor that interferes with the synthesis of dopamine in the hypothalamus and its transport to the pituitary gland and the interaction between dopamine and its receptors can weaken inhibitory regulation and cause hyperprolactinemia. Common causes can be summarized into four categories: physiological, pathological, pharmacological and idiopathic.

1. Physiological

Prolactin is a stress hormone that is secreted in pulses, with higher levels at night than during the day. It reaches its peak during the luteal phase of a woman's menstrual cycle and is at a low level during the follicular phase. It increases significantly during full-term pregnancy and after delivery. In addition, prolactin secretion increases significantly under stressful conditions. High-protein diet, exercise, stress and sexual activity, breastfeeding, nipple stimulation and sleep disorders can all lead to increased serum prolactin levels.

2. Pharmacology

Any drug that interferes with dopamine synthesis, metabolism, reabsorption or blocks the binding of dopamine to receptors can cause hyperprolactinemia, but the level is generally lower than 4.55nmol/L. Common drugs include estrogen, dopamine receptor blockers (such as antipsychotics, sedatives, antihypertensive drugs reserpine, monoamine oxidase inhibitors such as phenelzine, α-methyldopa), H2 receptor blockers (such as gastrokinetic drugs metoclopramide, metoclopramide and cimetidine, etc.), drugs that inhibit dopamine metabolism (such as opioid preparations), etc.

3. Pathological

It is mainly seen in hypothalamic-pituitary diseases, systemic diseases, ectopic prolactin production and other causes.

⑴ Hypothalamic lesions: such as craniopharyngioma, glioma, sarcoidosis, tuberculosis, etc. compressing the pituitary stalk; hypothalamic function is impaired after cranial radiotherapy.

⑵ Pituitary diseases: prolactin-producing pituitary microadenoma; somatotropin-producing pituitary adenoma, adrenocorticotropic hormone adenoma; empty sella syndrome, sarcoidosis, granulomatous disease, inflammatory lesions.

⑶ Systemic diseases: primary hypothyroidism; chronic renal failure; severe liver disease, cirrhosis, hepatic encephalopathy; certain tumors such as adrenal tumor, bronchial carcinoma, ovarian cystic teratoma.

⑷ Neurogenic: chest wall lesions, herpes zoster neuritis and breast surgery, etc.

⑸Others: polycystic ovary syndrome.

4. Idiopathic

Idiopathic hyperprolactinemia refers to elevated serum prolactin, usually <4.55nmol/L, with negative pituitary, central nervous and systemic examinations, but accompanied by symptoms such as lactation, oligomenorrhea and amenorrhea. The onset of the disease may be related to the heteromorphic structure of the prolactin molecule, and the course of the disease is self-limited.

Clinical manifestations

1. Lactation

It is the main clinical manifestation of hyperprolactinemia. About 2/3 of patients will lactate during the non-pregnancy and non-lactation period. Male patients may also experience breast development and lactation. The secreted milk is colostrum-like or watery, serous, yellow or white. In most cases, the amount is not much, and usually the milk will flow out only when squeezed. In severe cases, the milk may flow out on its own. Although lactation is closely related to increased blood prolactin levels, the amount of lactation has nothing to do with the degree of increase in prolactin levels. Lactation is more common in patients with pituitary microadenomas, accounting for about 70%; only 30% of patients with non-tumor hyperprolactinemia will experience lactation.

2. Menstrual disorders and amenorrhea

Patients may experience menstrual disorders, secondary amenorrhea, decreased libido, and in severe cases, genital atrophy and osteoporosis. When the patient has decreased lactation, menstrual flow or even amenorrhea, it is called amenorrhea-galactorrhea syndrome. Patients with polycystic ovary syndrome often have hyperprolactinemia. In addition to elevated prolactin, blood androgen levels are also elevated. They also have obesity, hirsutism, acne, and infrequent menstruation.

3. Infertility and sterility

Most cases of hyperprolactinemia are caused by pituitary microadenomas. About 90% of patients experience oligomenorrhea or amenorrhea, and infertility may also occur in about 70%. Men may experience decreased libido, poor sperm quality, and infertility.

4. Others

Patients with hyperprolactinemia caused by pituitary or intracranial tumors may also have headaches, blurred vision or visual field loss, blindness, diplopia, and hypopituitarism; those caused by growth hormone adenoma may also develop gigantism and acromegaly; those caused by adrenocorticotropic hormone adenoma may also develop Cushing's disease; those caused by thyrotropinoma may also develop hyperthyroidism and non-functioning tumors.