The thyroid is a gland, shaped like a butterfly, located at the bottom part of the neck. According to the National Institutes of Health, the job of the thyroid is to release hormones that affect metabolism. Hypothyroidism occurs when the thyroid does not release enough of these hormones, which will in turn affect the functions of the rest of the body, causing various symptoms.
Mental Signs
Some of the first signs of an underactive thyroid relate to mental well-being. A 2002 issue of "Molecular Psychiatry" reports that levels of thyroid hormones have an effect on the brain's serotonin levels. Since serotonin is a hormone that affects mood and pain perception, when its levels are out of balance, a person's sense of mood and well-being will also be affected. This results in the symptoms of depression and irritability. According to the Mayo Clinic, depression is an early symptom that tends to become worse as hypothyroidism continues, and it can be accompanied by impaired mental function. Unfortunately, many times depression is treated simply as depression, and the patient's thyroid function is not tested. This can result in misdiagnosis and inadequate treatment of the condition. While the patient is truly experiencing depression, it could be due to the fact that hypothyroidism is altering the serotonin levels, and not other causes.
Inward Signs
Other symptoms of hypothyroidism take place within the body, but not necessarily within the brain system. The American Academy of Family Physicians reports that those diagnosed with hypothyroidism have elevated cholesterol and triglyceride levels, which can lead to heart disease. Other signs within the body are a sense of fatigue, muscle weakness, muscle cramps, constipation, and even hearing loss.
Outward Signs
Signs of hypothyroidism can be seen on the outside of the body as well. The National Institutes of Health list dry, brittle nails, brittle hair, thinning eyebrows, thickening skin and unexplained weight gain as outward symptoms. A 2004 issue of "Clinical Endocrinology" states that those with hypothyroidism also have low grade inflammation. Inflammation can contribute to other outward, physical symptoms, which are puffiness and swelling in the hands, feet and/or face.
Pain
Those suffering from hypothyroidism can also experience different pain symptoms. The pain can take the form of crampy and achy muscles, general stiffness and tenderness throughout the body and joint swelling and stiffness, similar to arthritis. Women can experience heavier and more painful menstrual periods. One common symptom of hypothyroidism that also causes pain is cold intolerance. With cold intolerance, just being exposed to cold temperatures can cause pain in the extremities. The Mayo Clinic reports that in rare cases, the cold intolerance can become so severe that it can cause drowsiness, eventually leading to a coma.
