IS RARE AUTOIMMUNE DISEASE & IS CHARACTERIZED BY THE PRESENCE OF BLOCKING AUTOANTIBODIES TO THE THYROTROPIN RECEPTORS.
Medical Care
The treatment goals for hypothyroidism are the reversal of clinical progression and the correction of metabolic derangements as evidenced by normal blood levels of TSH and free T4. Thyroid hormone is administered to supplement or replace endogenous production. In general, hypothyroidism can be adequately treated with a constant daily dose of LT4.
Clinical benefits begin in 3-5 days and level off after 4-6 weeks. Anticipated full replacement doses may be initiated in individuals who are otherwise young and healthy. In elderly patients or those with known ischemic heart disease, treatment should begin with one fourth to one half the expected dose, and the dose should be adjusted in small increments every 4-6 weeks.
Achieving a TSH level within the reference range may be slowed because of delay of hypothalamic-pituitary axis readaptation. After dose stabilization, patients can be monitored with annual clinical evaluations and TSH monitoring. Patients should be monitored for symptoms and signs of overtreatment, which include tachycardia, palpitations, nervousness, tiredness, headache, increased excitability, sleeplessness, tremors, and possible angina.
Triiodothyronine (T3): Anecdotally, patients whose symptoms are not well controlled with T4 alone report benefits from combination therapy with T3 and T4. The optimal ratio of T4/T3 to be administered is not known, and, although some studies have shown an improvement in certain psychologic tests using a ratio of 4:1, other randomized trials have not confirmed this.
Pregnancy
Hypothyroidism in pregnancy is associated with preeclampsia, anemia, postpartum hemorrhage, cardiac ventricular dysfunction, spontaneous abortion, low birthweight, impaired cognitive development, and fetal mortality. Even mild disease may be associated with adverse affects for offspring.
Increased dosage requirements should be anticipated during pregnancy, especially in the first and second trimesters. Recent studies have suggested that patients with hypothyroidism should augment the LT4 dose by 30% at the confirmation of pregnancy, followed by adjustments according to TSH levels.
Subclinical hypothyroidism
Significant controversy persists regarding the treatment of patients with mild hypothyroidism. Some have argued that treatment of these patients improves symptoms, prevents progression to overt hypothyroidism, and may have cardioprotective benefits. Recent reviews by the American Medical Association and US Preventive Services Task Force have found inconclusive evidence to recommend aggressive treatment of patients with TSH levels of 4.5-10 mU/L.
Following subclinical hypothyroidism and treating on a case by case basis is reasonable.
Surgical Care
Surgery is indicated for large goiters that compromise tracheoesophageal function; surgery is rarely needed in patients with hypothyroidism and is more common in the treatment of hyperthyroidism.
Diet
No specific diets are required.
Activity
Patients who have hypothyroidism have generalized hypotonia and may be at risk for ligamental injury, particularly from excessive force across joints. Thus, patients should exercise caution with certain activities, such as contact sports or heavy physical labor.
Patients with uncontrolled hypothyroidism may have difficulty maintaining concentration in low-stimulus activities and may have slowed reaction times. Patients should use caution if an activity has a risk of injury (eg, operating presses or heavy equipment, driving).