Prolactin is a hormone secreted by the anterior pituitary gland and its major function is to stimulate milk production in women after childbirth. However, recent studies have also shown a connection between high Prolactin levels and the health of our hair – or lack thereof. It has been observed that higher levels of serum Prolactin are associated with excessive hair loss in the human body.
Hyperprolactinemia, i.e. high levels of Prolactin, is a normal change during pregnancy and breastfeeding, but in non-pregnant women it can be a sign of disease. This condition leads to progressive hair loss because of its effect on the levels of testosterone in the body.
Prolactin acts by increasing the receptors of Luteinizing Hormone in the Leydig Cells, testosterone producing cells that are found in men’s testicles and women’s ovaries. The increased testosterone secretion can cause hair loss in certain individuals because their hair follicles are genetically more sensitive to the elevated levels of the hormone, which causes the follicle to shrink.
Research on Hair Loss Due To High Prolactin Levels
In a recent study, organ-cultured human scalp was treated with a very high dose (400ng\ml) of Prolactin. The normal level of Prolactin is below 18ng\ml in men and 29 in women. The result was a significant decrease in the elongation of the hair shaft along with more hair prematurely moving into the catagen phase, when the hair gets cut off from the blood supply and stops growing. There was also elevated Apoptosis, which is increased natural cell death of the hair bulb keratinocytes (cells in the skin with a protective function), which can lead to hair loss.
Reasons for Increased Prolactin Secretion
Hyperprolectinemia can be caused by the following:
• Prolactinoma, a non-cancerous swelling of the pituitary gland, which leads to increased secretions of Prolactin.
• Increased secretion of TRH (Thyrotropin-Releasing Hormone) due to Hypothyroidism, stimulates the secretion of Prolactin.
• Excessive use of anti-depressants such as Selective Serotonin Reuptake Inhibitors (SSRIs), Benzodiazepines (such as Alprazolam, Diazepam and Lorazepam), and Tricyclic Antidepressants (such as Imipramine, Amitriptyline, and Nortriptyline).
• Any psychotic disorder or chronic anxiety syndrome.
• During pregnancy and lactation there is increased secretion of the hormone Oxytocin which in turns stimulates increased secretion of Prolactin.
• Increased levels of Estrogen during the end of gestational period also causes elevated levels of Prolactin. Paradoxically, Estrogen is also said to prolong the growing phase (anagen phase) of the hair cycle, which is why women’s hair can be thicker during pregnancy. More on Estrogen and how it is affecting the hair can be found in this text.
Reasons for Decreased Levels of Prolactin
• Excessive daylight exposure can decrease the levels of Prolactin in the body.
• Increased release of Dopamine by the Hypothalamus also inhibits Prolactin’s secretion.
Pharmacological Treatment of High Prolactin Levels
One recent study has shown that use of Dopamine Receptor Agonists such as Bromocriptine, Cabergoline, Pergolide and Quinagolide significantly reduces the levels of Prolactin in the body due to increased secretion of Dopamine.
All of these dopamine agonists have the same mechanism of action and minimal side effects. However, studies have shown that Cabergoline has the highest efficacy and drug tolerability for children and adolescents. Hence, Cabergoline should be the drug-of-choice for the treatment of Hyperprolactinemia, especially in young children and teenagers.
High Prolactin levels are emerging as a potential reason for increased hair loss in many people. Hence, levels of Prolactin should be checked in case of massive hair loss or Alopecia in order to treat these issues accordingly.