Methods of prolactin test in patients with amenorrhea and galactorrhea syndrome

Prolactin test for patients with amenorrhea and galactorrhea syndrome is helpful to distinguish functional increased secretion of prolactin from pituitary adenoma and understand the reserve power of hypothalamic-pituitary function. If prolactin is significantly increased, it indicates that hypothalamic-pituitary dysfunction is more likely. There are mainly the following methods:

Thyrotropin-releasing hormone stimulation test

When normal women are given an intravenous injection of 500 μg of thyrotropin-releasing hormone, their blood prolactin level can increase to above 0.16 nmol/L 15 minutes later, which is 2 times higher than the basal value. However, the release effect of thyrotropin-releasing hormone in patients with pituitary tumors is lower than normal.

Chlorpromazine stimulation test

After intramuscular injection of 25-50 mg of chlorpromazine, prolactin generally doubles within 60-90 minutes and can last for 3 hours. A positive result indicates that hyperprolactinemia may be caused by dysfunction. Hormone secretion in patients with pituitary tumors is somewhat autonomous and less affected by stimulation.

Metoclopramide test

Metoclopramide is a dopamine antagonist that acts on dopamine receptors at the hypothalamic and pituitary levels to stimulate prolactin release. In patients with pituitary prolactin-secreting tumors, oral or intravenous administration of 10 mg of metoclopramide resulted in a peak prolactin response of only 1/4 of the baseline value, while in normal people, the peak prolactin response reached more than 3 times the baseline value.

Levodopa test

Normal people take 500mg of levodopa orally, and the blood prolactin level drops significantly to <4ng/ml within 2-3 hours. If there is no significant drop, it means that the secretion of prolactin is autonomous and not inhibited. In this case, the possibility of pituitary tumor is high.