Hypothyroidism is a condition in which the thyroid gland is not able to produce enough thyroid hormone. The main purpose of the thyroid hormone is to maintain energy metabolism (how effectively the body uses calories). As a result, the symptoms of this condition are associated with a slow metabolism.

These symptoms differ with age and sex and other factors. Most frequently reported are:

Fatigue; weakness; weight gain; decreased growth in length in the child; coarse, and dry hair; hair loss;  dry, rough pale skin;  cold intolerance; muscle cramps and frequent muscle aches, constipation, depression, irritability, and memory loss.

The cause of hypothyroidism is diverse from a congenital anomaly, an autoimmune disease, to a part of another know chronic condition such as Down Syndrome and Turner Syndrome. In the conditions with an elevated risk of hypothyroidism, the symptoms may be hard to distinguish.

Because of the large variation and often nonspecific clinical presentations, hypothyroidism is defined when thyroid-stimulating hormone (TSH) concentrations are above the reference range and free thyroxine concentrations below the reference range.

Levothyroxine monotherapy in solid formulation, taken on an empty stomach, is the first treatment of choice.

Reference:

Layal Chaker, et al. Hypothyroidism Lancet. 2017 September 23; 390(10101): 1550–1562. doi:10.1016/S0140-6736(17)30703-1