QUESTION 2

2.What do you think were the serum T3,T4, and TSH levels in the previous consult? What do you call this condition? – Low circulating levels of T 4 and T 3 – Primary Thyroid Failure Raised TSH levels – Secondary Hypothyroidism Low TSH levels that do not increase following TRH stimulation

HYPOTHYROIDISM Deficiency in the circulating levels of thyroid hormone leads to hypothyroidism, and, in neonates, to cretinism, which is characterized by neurologic impairment and mental retardation. – Hypothyroidism may also be associated with deafness (Pendred's syndrome)4 and Turner's syndrome.

In adults, symptoms in general are nonspecific: – Tiredness, weight gain, cold intolerance, constipation, and menorrhagia – Patients with severe hypothyroidism or myxedema Facial and periorbital puffiness – Characteristic facial features as a consequence of the deposition of glycosaminoglycans in the subcutaneous tissues The skin becomes rough and dry and often develops a yellowish hue from reduced conversion of carotene to vitamin A. Hair becomes dry and brittle, and severe hair loss may occur Loss of the outer two-thirds of the eyebrows.

– An enlarged tongue may impair speech, which is already slowed, in keeping with the impairment of mental processes. – Myxedema madness Untreated dementia – Nonspecific abdominal pain accompanied by distention and constipation. – Libido and fertility are impaired in both sexes. – Cardiovascular changes in hypothyroidism include: Bradycardia, cardiomegaly, pericardial effusion, reduced cardiac output, and pulmonary effusions Cardiac failure is uncommon When hypothyroidism occurs as a result of pituitary failure, features of hypopituitarism such as pale, waxy skin, loss of body hair, and atrophic genitalia may be present

LABORATORY FINDINGS Hypothyroidism is characterized by low circulating levels of T 4 and T 3. Raised TSH levels are found in primary thyroid failure, whereas secondary hypothyroidism is characterized by low TSH levels that do not increase following TRH stimulation. Thyroid autoantibodies are present and are highest in patients with autoimmune disease (Hashimoto's thyroiditis, Graves' disease), although they are also elevated in patients with nodular goiter and thyroid neoplasms. Other findings include anemia, hypercholesterolemia, and decreased voltage with flattening or inversion of T waves on electrocardiogram. Comatose patients with myxedema also have hyponatremia and CO 2 retention.

TREATMENT THYROXINE Treatment of choice – 50 to 200 mcg per day, depending upon patient's size and condition. – Starting doses of 100 mcg of thyroxine daily are well tolerated – Elderly patients and those with coexisting heart disease and profound hypothyroidism should be started on a considerably lower dose such as 25 to 50 mcg daily because of associated hypercholesterolemia and atherosclerosis. – The dose can be slowly increased over weeks to months to attain a euthyroid state.

A baseline ECG should always be obtained in patients with severe hypothyroidism prior to treatment. Patients are instructed to take tablets in the morning, usually without other medications, or at mealtime to assure good absorption. Thyroxine dosage is titrated against clinical response and TSH levels, which should return to normal. Patients who present with myxedema coma, in contrast to the patients with mild to moderate hypothyroidism, require an initial emergency treatment with large doses of intravenous thyroxine (300 to 400 g), and careful monitoring in an ICU setting.