Background: Hypothyroidism is a condition that characterized by abnormally low thyroid hormone production. There are many disorders that result in hypothyroidism. These disorders may directly or indirectly involve the thyroid gland. Because thyroid hormone affects growth, development, and many cellular processes, inadequate thyroid hormone has diffuse consequence for the body. Hypothyroidism is the commonest pathological hormone decrease, the variety of end-organ effects and wide range of disease severity make it an elusive clinical entity. The early assessment of hypothyroidism remains a big aim, particularly when the decrease in thyroid function is gradual. In some instances, the manifestations were simply attributed to the effects of aging in the elderly. Infrequently, hypothyroidism may progress to myxedema coma; a state characterized by defective thermoregulation and altered mental status to the point of coma after a precipitating event. The symptoms of hypothyroidism are often not specific (which means they can like the symptoms of many other conditions). Symptoms generally become more evident as the condition worsens and a lot of these complaints are related to a metabolic slowing of the body. Common symptoms are : Fatigue , Depression, weight gain, Excessive sleepiness, Cold intolerance, Constipation, Dry, course hair, Dry skin, low concentration, Swelling of the legs, Vague aches and pain, uscle cramps. The treatment goals for hypothyroidism are to invert clinical progression and correct metabolic derangements, as evidenced by normal blood levels of thyroid-stimulating hormone (TSH) and free thyroxine (T4). Thyroid hormone is administered to replace endogenous production. In general, hypothyroidism can be adequately treated with a constant daily dose of levothyroxine (LT4).Thyroid hormone can be started at a full replacement doses in individuals who are young and otherwise healthy. In elderly patients and those with known ischemic heart disease, treatment should begin with one fourth to one half the expected dosages, and the dosage should be adjusted in small increases.