Grave's Disease


Overview
  • Most common cause of hyperthyroidism in countries with sufficient iodine intake.
  • Caused by TSH receptor antibodies.
  • Extrathyroidal manifestations include ophthalmopathy, pretibial myxedema (thyroid dermopathy), or acropachy, which do not occur with other causes of hyperthyroidism.
  • Diagnostic tests are suppressed serum TSH, elevated levels of circulating thyroid hormones, and high thyroid uptake of radioactive iodine.
  • Treatment options are radioactive iodine therapy, antithyroid drugs, and surgery.
  • Untreated hyperthyroidism, particularly in older people, may result in cardiac arrhythmias, high-output cardiac failure, bone mineral loss, and rarely thyroid storm.
  • Unusual complications include vision loss secondary to ophthalmopathy or elephantiasis secondary to dermopathy
Hx and Exam
  • FHx autoimmune thyroid disease
  • hx of tobacco use
  • heat intolerance, Sweating, weight loss
  • Palpitations, tremor, tachycardia
  • diffuse goiter
  • ophthalmopathy
  • irritability
  • wide pulse pressure
  • thyroid bruit
  • cardiac flow murmur
  • onycholysis (characterized by a spontaneous separation of the nail plate starting at the distal free margin and progressing proximally)
  • moist, velvety skin
  • vitiligo
  • scalp hair loss
  • pretibial myxedema
  • acropachy
Diagnostic Tests
  • TSH
  • serum free T4
  • serum free or total T3
  • T3RU, free T4 index
  • radioactive iodine uptake
  • thyroid isotope scan
  • TSH receptor antibodies (TRAb)
  • thyroid ultrasound
  • CT orbit (noncontrast)
  • skin biopsy
Treatment
  1. To Protect Organs:
    • propranolol hydrochloride : adults: 80-160 mg orally (extended-release) once daily
    • atenolol : adults: 50-100 mg orally once daily
    • diltiazem : adults: 120-240 mg orally (extended-release) once daily
    • verapamil : adults: 120-240 mg orally (extended-release) once daily
       
  2. To Control Disease:
    • Primary Options
      • Methimazole : adults: 10-30 mg/day orally initially, adjust according to response; usual maintenance dose: 5-15 mg/day
    • Secondary Options
      • Propylthiouracil (PTU): adults: 150-400 mg/day orally initially given in 3 divided doses, adjust according to response; usual maintenance dose: 50-150 mg/day given in 2-3 divided doses
        • First-line in Pregnancy
        • Monitor AST/ALT, CBC
           
  3. Radioactive Iodine Ablation
    • Preferred Definitive Treatment
    • Can worsen pre-existing orbitopathy
    • Can cause transient hyperthyroidism (which is why pt should be treated with Methimazole prior to starting iodine)
       
  4. Surgery:
    • uncommon today
    • For thyroid nodule or cancer
    • For pts who cannot tolerate medications or wont take medications
    • Preoperative medical preparation:
      • propranolol hydrochloride : adults: 80-160 mg orally (extended-release) once daily o
      • atenolol : adults: 50-100 mg orally once daily
        -- AND/OR --
      • methimazole : adults: 10-30 mg/day orally initially, adjust according to response; usual maintenance dose: 5-15 mg/day or
      • propylthiouracil : adults: 150-400 mg/day orally initially given in 3 divided doses, adjust according to response; usual maintenance dose: 50-150 mg/day given in 2-3 divided doses
        -- AND/OR --
      • potassium iodide : adults: (SSKI 1 g/mL) 0.1 to 0.3 mL (3-5 drops) orally three times daily for 7-10 days before surgery
    • Postoperative thyroid replacement:
      • levothyroxine : adults: 1.7 micrograms/kg/day orally, adjust dose according to response and laboratory value

         
  5. Pregnancy:
    • First Trimeste: PTU
    • 2nd & 3rd Trimester: Methimazole

ITE 2013, Q63
Pretibial myxedema is a cutaneous manifestation of
A) subclinical diabetes mellitus
B) collagen vascular disease
C) hyperlipidemia, type III
D) ischemia
E) Graves disease