The endocrine system produces hormones that travel through the body and participate in a number of chemical processes. Hormones play a role in premenstrual syndrome, the retention and excretion of water by the kidneys and weight control. Disorders of the glands cause symptoms that include weight gain, weight loss, excessive thirst, excessive urination and headaches. Thyroid disease is one of the most common disorders of the endocrine system. Other disorders include adrenal fatigue, hormonal imbalances and others.