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  1. Causes of decreased T4 to T3 conversion
    • Nonthyroid illnesses
    • Drugs: propranolol, corticosteroids, propylthiouracil, amiodarone
  2. TSH
    • -under thyrotropin-releasing hormone influence
    • -stimulates - iodine uptake, organification
    • -T3 & T4 are bound to thryoxine-binding globulin (TBG), transthyretin, albumin
    • -estrogens, corticosteroids affect levels of TBG w/o affecting free levels of hormone
  3. Hypothyroid screening (TSH screening)
    • women aged >50
    • high risk pop:
    • -FHx of hashimoto/graves
    • -other autoimmune dx - e.g. type 1 dm
    • -hx of prior thyroid dysfn
    • -iodine-deficient region of world
    • -women anticipating/are pregnant
  4. 1. Primary hypothyroidism
    2. Subclinical hypothyroidism
    3. Secondary hypothyroidism
    4. Thyroid peroxidase antibody
    5. Thyroglobulin
    • 1. decreased T4 -> increased TSH
    • 2. normal T4 -> increased TSH
    • 3. decreased T4 -> decreased/not elevated TSH
    • 4. autoimmune thyroid disease -> Hashimoto's marker
    • 5. protein in follicles stores - elevated in hyperthyroidism and destructive thyroiditis - useful in determining exogenous toxicity
  5. Thyrotoxicosis
    • = hyperthyroidism (Graves Disease most common) or thyroiditis
    • -rare: hot adenoma, multinodular goiter, tsh consumption, struma ovarri
    • -lithium and amiodarone can induce thyroditis
  6. Caused or aggravated by thyrotoxicosis
    A. Fib, osteoporosis, weight loss, anxiety

    -s+s: nervousness, sweating, heat intolerance, palpitations, fatigue, weight loss, afib, tachy, goiter, tremor, proptosis, lid leg, pretibial myxedema
  7. Hypothyroidism
    Sluggish affect, depression, fatigue, cold tolerance, weight gain, alopecia, coarse dry hair, periorbital puffiness, bradycardia, slow mvmt/speech
  8. T3 Thyrotoxicosis (subclinical hyperthyroidism)
    • -suppressed TSH, normal T4
    • -get serum t3 level
    • -usu toxic multinodular goiter
  9. Radioactive Iodine Uptake and Scan
    • -used to differentiate between thyrotoxicosis and thyroditis
    • -elevated and diffuse - graves
    • -normal/elevated focal area - nodule
    • -low/absent - thyroiditis
  10. Thyroid Nodules
    • Cancer risk:
    • 1. young age (<30 years)
    • 2. male sex
    • 3. a history of head or neck irradiation
    • 4. fhx
    • 5. rapid nodule growth, larger nodules, and hoarseness.

    Hot nodules are rarely malignant

    -if euthyroid w/ nodules - U/S; >1cm should be biopsied (10-15% risk of ca), else may be if cancer rfs
  11. Thyrotoxicosis Treatment
    Methimazole is generally recommended as first-line antithyroid therapy, as propylthiouracil has been associated with elevated aminotransferase levels and a higher rate of serious adverse effects on the liver than occur with methimazole. An exception is women who are in the first trimester of pregnancy, during which methimazole has been associated with possible teratogenicity. Propylthiouracil is also preferred in patients with an allergy to methimazole. With either drug, patients should be counseled about the risk of the rare but severe side effects of agranulocytosis, hepatitis, and vasculitis. Rarely, severe hepatic necrosis has been reported, predominantly with propylthiouracil.
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2013-02-12 02:17:29

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