hypothyroidism. Trisomy 21 and Turner syndrome are predisposed to the development of autoimmune thyroiditis.
The diagnosis may be confirmed by serum antithyroid peroxidase (previously antimicrosomal) and antithyroglobulin antibodies. Neither biopsy nor thyroid scan is indicated in Hashimoto thyroiditis, although the thyroid scan with reduced uptake may differentiate hashitoxicosis from Graves disease.
Treatment with thyroid hormone sufficient to normalize TSH and free T4 is indicated for hypothyroidism in Hashimoto thyroiditis. Patients without manifestation of hypothyroidism require thyroid function testing (serum TSH and free T4)every 6 to 12 months to detect the later development of hypothyroidism. Goiter with a normal TSH usually is not an indication for treatment.
Available @ StudentConsult.com
Most children with hyperthyroidism have Graves disease, the autonomous functioning of the thyroid caused by autoantibodies [thyroid stimulating immunoglobulins (TSIs)] stimulating the thyroid. The resulting excessive synthesis, release, and peripheral metabolism of thyroid hormones produce the clinical features. Hashimoto thyroiditis and thyrotoxicosis are on a continuum of autoimmune diseases; there is overlap in their immunologic findings. Antithyroid peroxidase and antithyroglobulin antibodies may be present in thyrotoxicosis, although the values are usually lower than in Hashimoto thyroiditis. Exceptionally high titers of antibodies may indicate the thyrotoxic phase of Hashimoto thyroiditis with the subsequent evolution toward permanent hypothyroidism. In Graves disease, serum free T4 or T3 or both levels are elevated, whereas TSH is suppressed. Rare causes of hyperthyroidism include McCune-Albright syndrome, thyroid nodule (often an adenoma), TSH hypersecretion, subacute thyroiditis, and iodine or thyroid hormone ingestion.
Clinical manifestations. Graves disease presents as hyperthyroidism (Table 175-4) and is about five times more common in girls than in boys, with a peak incidence in adolescence. Personality changes, mood instability, and poor school performance are common initial problems. Tremor, anxiety, inability to concentrate, and weight loss may be insidious and confused with a psychological disorder until thyroid function tests reveal the elevated serum free T4 level. In rare cases, serum free T4 may be near-normal whereas serum T3 is selectively elevated (T3 toxicosis). A firm homogeneous goiter is usually present. Many patients complain of neck fullness. Thyroid gland enlargement is best visualized with the neck only slightly extended and with the examiner lateral to the patient. Palpation of the thyroid gland is best performed with the examiner’s hands around the neck from the back. The patient swallows so that the examiner can feel and examine the size, consistency, nodularity and motion of the gland. The examiner should watch the patient swallow to note any discernible enlargement or asymmetry of the thyroid lobes. Auscultation may reveal a bruit over the gland that needs to be differentiated from a carotid bruit.
Treatment. Three treatment choices are available: pharmacologic, radioactive iodine, and surgical.
Drugs. Medical therapy to block thyroid hormone synthesis consists of methimazole (0.4 to 0.6 mg/kg/day once or
Shiny, smooth skin
Cardiac failure—dyspnea Miscellaneous Proptosis, stare, exophthalmos, lid lag, ophthalmopathy
Inability to concentrate
Acute thyroid storm (hyperpyrexia, tachycardia, coma, high-output heart failure, shock) *Unusual except in subacute thyroiditis with hyperthyroid phase.