> Low [[thyroid]] function and intestinal inflammation are usually involved, with increased endotoxin, nitric oxide, endorphins, serotonin, sometimes prolactin and an increased ratio of estrogen to progesterone and the androgens. A deficiency of vitamin D and calcium is sometimes involved. [Source](https://lowtoxinforum.com/threads/ray-peat-email-advice-depository.1035/post-215035)