Hyperthyroidism

Etiologies (loncrt 2003:362:459)

• Graves' disease (60-80% of thyrotoxicosis)

• Thyroiditis: thyrotoxic phase of subacute thyroiditis

• Toxic adenomas (single or multinodular goiter) or. rarely, functioning thyroid carcinoma

• TSH-secreting pituitary tumor or pituitary resistance to thyroid hormone (' TSH. i freeT.»)

• Mise: amiodarone. iodine-induced, thyrotoxicosis factitia, struma ovarii (3% of ovarian dermoid tumors and teratomas). hCG-secreting tumors (eg. choriocarcinoma)

Graves' disease

• Female:malo ratio is 5-10:1. most Pts between 40-60 y at dx

• < thyroid antibodies: TSI ( *) in 80%). antimicrosomal. antithyroglobulin; ANA

• Clinical manifestations in addition to those of hyperthyroidism (see below):

goiter: diffuse, nontender. w thyroid bruit ophthalmopathy (50%; up to 90% if formally tested): periorbital edema, proptosis (✓ if sclera visible between lower iris and lower lid), conjunctivitis, diplopia (EOM infiltration); associated w smoking pretibial myxedema (3%); infiltrative dermopathy

Clinical manifestations of hyperthyroidism

• Restlessness. sweating, tremor, moist warm skin, fine hair, tachycardia. AF. weight loss.

f frequency of stools, menstrual irregularities, hyperreflexia. osteoporosis, stare and lid lag (due sympathetic overactivity)

• Subclinical (. TSH. normal FT« and Tj): t risk of atrial fibrillation and osteoporosis.

may account for 10% of new-onset AF (Nejm 2001;34S:S12)

• Apathetic thyrotoxicosis: seen in elderly who can present with lethargy as only sx

• Thyroid storm (extremely rare): delirium, fever, tachycardia, systolic hypertension but wide pulse pressure and i MAP. Gl symptoms: 20-50% mortality Laboratory testing

• T FT* and FTj; 4 TSH (except in TSH-secreting tumors)

• RAIU scan is very useful study to differentiate causes (see table on page 7-3)

• Rarely need to ✓ for autoantibodies except in pregnancy (to assess risk of fetal Graves')

• May see hypercalciuria • hypercalcemia. * A<Jj. anemia

Treatment

• (i-blockers: control tachycardia (propranolol also A T« -»Tj conversion)

• Graves' disease: either antithyroid drugs or radioactive iodine (NEJM 200S;3S2305)

propylthiouracil (PTU) or methimazole: 50% chance of recurrence after 1 y;

side effects include pruritus, rash, arthralgia, fever. N V. and agranulocytosis in 0.5% radioactive iodine (RAI): preRx w antithyroid drugs to prevent T thyrotoxicosis.

stop > 5 d before to allow RAI uptake; > 75% of treated Pts become hypothyroid surgery: rarely chosen for Graves', usually for Pts w obstructive goiter

• Toxic adenoma or toxic multinodular goiter: RAI or surgery (• PTU or methimazole preRx)

• Thyroid storm: |}-blocker. PTU. iopanoic acid or iodide (for "Wolff-Chaikoff" effect) -1 h after PTU. • steroids (IT« -.Tj)

• Ophthalmopathy: can worsen after RAI. sometimes responds to prednisone; can be treated w radiation and or surgical decompression of the orbits

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