Hypothyroidism therapy

Thyroid-stimulating hormone can be used clinically to test thyroid function but has not found practical apphcation in the treatment of human thyroid insufficiency. Direct replacement therapy with thyroid hormone is easy and effective, owing to a simple molecular stmcture. TSH has been used in the veterinary treatment of hypothyroidism, and preparations of TSH ate produced by Cooper Animal Health, Inc. and Armour Pharmaceuticals. 

Decreased activity of the thyroid gland results in hypothyroidism and, in severe cases, myxoedema. It is often of immunological origin and the manifestations are low metabolic rate, slow speech, lethargy, bradycardia, increased sensitivity to cold, and mental impairment. Myxoedema includes a characteristic thickening of the skin. Therapy of thyroid tumours is another cause of hypothyroidism. Thyroid deficiency... 

Ovarian enlargement, hemoperitoneum, febrile reactions, multiple pregnancies, hypersensitivity Failure to respond to therapy due to development of antibodies, hypothyroidism, insulin resistance, swelling of the joints, joint and/or muscle pain Same as somatropin... 

These hormones cause few adverse reactions when administered as directed. Antibodies to somatropin may develop in a small number of patients, resulting in a failure to experience response to therapy, namely, failure of the drug to produce growth in the child. Some patients may experience hypothyroidism or insulin resistance Swelling, joint pain, and muscle pain may also occur. 

Thyroid hormones are used as replacement therapy when the patient is hypothyroid. By supplementing the decreased endogenous thyroid production and secretion with exogenous thyroid hormones, an attempt is made to create a euthyroid (normal thyroid) state Levotliyroxine (Synthroid) is the drug of choice for hypothyroidism because it is relatively inexpensive, requires once-a-day dosages, and lias a more uniform potency than do other thyroid hormone replacement drugs. 

After a patient receives a diagnosis of hypothyroidism and before therapy starts, the nurse takes vital signs and weighs the patient. A history of the patient s signs and symptoms is obtained. The nurse performs a general physical assessment to determine outward signs of hypothyroidism. 

The symptoms of hypothyroidism maybe confused with symptoms associated with aging, such as depression, cold intolerance, weight gain, confusion, or unsteady gait. The presence of these symptoms should be thoroughly evaluated and documented in the preadministration assessment and periodically throughout therapy. 

Replacement therapy is for life, witii the exception of transient hypothyroidism seen in those with tiiy-roiditis. 

Once a euthyroid state is achieved, tlie primary health care provider may add a thyroid hormone to tlie therapeutic regimen to prevent or treat hypothyroidism, which may develop slowly during long-term antithyroid drug therapy or after administration of 131I. 

IVday, monitor urinalysis, osmolality, and specific gravity every 3 months. Thyroid function tests should be obtained once or twice during the first 6 months, then every 6-12 months monitor for signs and symptoms of hypothyroidism if supplemental thyroid therapy is required, monitor thyroid function tests and adjust thyroid dose every 1-2 months until thyroid function indices are within normal range, then monitor every 3-6 months. 

LT4 is indicated for patients with overt hypothyroidism.22 However, the need for treatment is controversial in patients with mild or subclinical disease (TSH less than 10 milli-units/L). There are no large clinical trials that show an outcome benefit with treating these patients, and the therapeutic decision must be individualized.1,23 Many patients with subclinical hypothyroidism do, in fact, have subtle symptoms that improve with LT4 replacement. If the patient s serum cholesterol is elevated,24 or if serum anti-TPOAbs are present, many clinicians recommend LT4 therapy. 

Use serum TSH to identify patients with hypothyroidism and to monitor LT4 replacement therapy. 

The target TSH for patients on LT4 replacement therapy for hypothyroidism is 0.5 to 2.5 milliunits/L. Most patients feel best at a TSH level in the low- to middle-normal range (i.e., 0.5-1.5 milliunits/L). ... 

Subtotal thyroidectomy is indicated in patients with very large goiters and thyroid malignancies and those who do not respond or cannot tolerate other therapies. Patients must be euthyroid prior to surgery, and patients often are administered iodide preoperatively to reduce gland vascularity. The overall surgical complication rate is 2.7%. Postoperative hypothyroidism occurs in 10% of patients who undergo subtotal thyroidectomy. 

Antithyroid drugs have a delayed effect. After 2 to 4 weeks of therapy, adjust the dose if the TSH is not in the target range (0.5-2.5 milliunits/L). Once the patient is euthyroid, consider reducing the dose of antithyroid drug to avoid hypothyroidism. 

Lithium is associated with hypothyroidism in up to 34% of patients, and hypothyroidism may occur after years of therapy. Lithium appears to inhibit thyroid hormone synthesis and secretion. Patients with underlying autoimmune thyroiditis are more likely to develop lithium-induced hypothyroidism. Patients may require LT4 replacement even if lithium is discontinued. 

Interferon-a causes hypothyroidism in up to 39% of patients being treated for hepatitis C infection. Patients may develop a transient thyroiditis with hyperthyroidism prior to becoming hypothyroid. The hypothyroidism may be transient as well. Asians and patients with preexisting anti-TPOAbs are more likely to develop interferon-induced hypothyroidism. The mechanism of interferon-induced hypothyroidism is not known. If LT4 replacement is initiated, it should be stopped after 6 months to re-evaluate the need for replacement therapy. 

In patients with thyroid cancer, the desired outcomes with LT4 therapy often are different from those in the hypothyroid patient. 

Children treated with GH replacement therapy rarely experience significant adverse effects, whereas adults are more susceptible to dose-related adverse effects. Treatment with GH may mask underlying hypothyroidism. GH-induced symptoms, such as edema, arthralgia, myalgia, and carpal tunnel syndrome, are common and necessitate dose reductions in up to 40% of adults. Benign increases in intracranial pressure may occur with GH therapy and generally are reversible with discontinuation of treatment. Often, GH therapy can be restarted with smaller doses without symptom recurrence. 

Yearly TSH determinations, particularly for women with hypothyroidism on thyroid therapy... 

Pituitary failure (secondary hypothyroidism) is an uncommon cause resulting from pituitary tumors, surgical therapy, external pituitary radiation, postpartum pituitary necrosis, metastatic tumors, tuberculosis, histiocytosis, and autoimmune mechanisms. 

The disorder is not caused by a medical condition (eg., hypothyroidism) or substance-induced disorder (eg., antidepressant treatment, medications, electroconvulsive therapy). 

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