Premenstrual syndrome (PMS) and the more severe form, premenstrual dysphoric disorder (PMDD), are linked to changes in the endocrine system, which produces hormones that control the menstrual cycle. Because the female endocrine system is so complex, medical experts don't fully understand the chain of events that causes PMS in some women and not others.

The one direct cause that is known to affect some women is genetic-many women with PMS have a close family member with a history of PMS.¹

Just as your combination of PMS symptoms is slightly different from another woman's, so is the mix of factors underlying your symptoms. Changes in the endocrine system that cause PMS symptoms can include:

• Increased aldosterone (a hormone from the adrenal gland). This is normal after ovulation. Aldosterone causes fluid retention, weight gain, breast swelling, and headaches in some women but not others.²
• Too much prolactin (a hormone from the pituitary gland), which can interfere with ovulation and cause irregular cycles and breast tenderness.²
• The brain's underuse of the neurotransmitter serotonin, which is known to cause anxiety and depression. Experts theorize that many women with PMS mood problems are sensitive to normal premenstrual changes in estrogen and progesterone (from the ovaries). This sensitivity may trigger a problem with the brain's use of serotonin.³
• Decreased endorphins (hormones from the pituitary gland), which may increase pain and depression in some women.²
• Prostaglandins (chemicals made by all body cells), which are linked to breast pain, fluid retention, cramping, headaches, irritability, and depression.²
• Sensitivity to insulin, which is thought to be common during the premenstrual time following ovulation. This sensitivity can lead to episodes of low blood sugar, which some researchers think may trigger premenstrual symptoms.²