Hyperprolactinemia (high prolactin blood levels or hyperprolactinaemia) from pituitary adenoma tumors can cause erectile dysfunction (ED). The cost-effective way to study ED from an endocrine abnormality is to test serum testosterone levels. Men with ED and low testosterone should have blood prolactin tested. If testosterone is very low, tests should be done for luteinizing hormone, free testosterone levels and prolactin levels.
Dopamine agonists, such as the pharmaceutical bromocriptine, can increase dopamine effect to lower prolactin levels and shrink pituitary adenomas. Prolactin blood levels are used to monitor the progress of therapy. Bromocriptine inhibits the pituitary secretion of prolactin. Shrinkage of the adenoma tumors with bromocriptine, or other dopamine agonist therapy, relieves headaches and any visual field defects due to the pituitary tumor.
An obese male with ED, who had very low testosterone levels and very high prolactin levels, was studied by the authors. A brain scan showed a large pituitary adenoma, which was surgically removed. Continued moderately elevated prolactin levels indicated that the tumor was not fully removed. Treatment was started to further lower prolactin blood levels, pharmaceutically.
Prolactin is produced by the pituitary tumor. Hyperprolactinemia interferes with the hypothalamic production of gonadotrophin-releasing hormone. This reduces production of testosterone, causing hypogonadism, ED and reduced libido. Hypogonadism is often seen in men with ED caused by endocrine problems. Testosterone does not relieve the ED unless the prolactin levels have returned to normal.
Many medications, many of which are used for depression, have the side effect of increasing prolactin levels by acting as dopamine antagonists. Normally, dopamine from the hypothalamus would inhibit pituitary production of prolactin.
CONCLUSION: Elevated blood levels of prolactin from pituitary adenomas can be associated with ED; endocrine causes of ED are rare. Dopamine agonists can lower prolactin levels, shrink the tumor and relieve ED. (Vitex agnus casti is a dopamine agonist.)
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