Graves' Disease

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Graves': Pathophysiology - Antibody Mayhem

  • Autoimmune: Type II hypersensitivity.
  • Key Antibody: TSH Receptor Antibody (TRAb).
    • Primarily Thyroid Stimulating Immunoglobulins (TSI).
    • Mimics TSH, activates TSH receptor (TSHR).
  • Mechanism:
    • TRAb binds TSHR → ↑ intracellular cAMP.
    • Stimulates thyroid hormone (T3, T4) synthesis & secretion.
    • Promotes thyroid follicular cell growth/proliferation → goiter.
  • Feedback Loop: ↑ T3/T4 → ↓ pituitary TSH.
  • Genetic Links: HLA-DR3, CTLA-4.
  • Triggers: Stress, infection, smoking, iodine. Graves' Disease Pathophysiology and Antibody Action

⭐ TRAb can be stimulating, blocking, or neutral. In Graves', stimulating antibodies (TSI) predominate, causing hyperthyroidism.

Graves': Clinical Features - Eye‑Popping Signs

  • General Hyperthyroidism: Weight loss, palpitations, heat intolerance, tremor.
  • Graves' Ophthalmopathy (GO) / Thyroid Eye Disease (TED): Specific autoimmune manifestation.
    • Proptosis (exophthalmos): Forward protrusion of eyeballs.
    • Lid retraction (Dalrymple's sign): Causes a "staring" appearance.
    • Lid lag (von Graefe's sign): Upper eyelid lags behind globe on downward gaze.
    • Diplopia (double vision), periorbital edema, chemosis (conjunctival edema).
    • Optic neuropathy (in severe cases): Can lead to vision loss.
  • Specific Extrathyroidal Manifestations:
    • Pretibial myxedema (Graves' dermopathy): Localized, infiltrative dermopathy; waxy, discolored induration of the skin ("orange peel" or peau d'orange appearance), typically on anterior shins.
    • Thyroid acropachy: Rare; digital clubbing, soft tissue swelling of hands and feet, periosteal new bone formation.
    • Goiter: Diffuse, usually firm, and may have a vascular bruit.

Graves' ophthalmopathy: normal vs affected eye

⭐ Lid retraction is the most common and often earliest sign of Graves' ophthalmopathy; it can occur even when the patient is euthyroid or hypothyroid after treatment for Graves' hyperthyroidism.

Graves': Diagnosis - Spotting the Storm

  • Initial Tests:
    • ↓ TSH (often < 0.01 mIU/L)
    • ↑ Free T4 (FT4) & ↑ Free T3 (FT3)
  • Confirmatory Test:
    • TSH Receptor Antibodies (TRAb): Positive (diagnostic)
      • Thyroid Stimulating Immunoglobulins (TSI) is a type of TRAb.
  • Radioactive Iodine Uptake (RAIU) Scan:
    • Shows diffuse, increased uptake.
    • Helps differentiate from other hyperthyroid causes.

⭐ TRAb positivity is the most specific laboratory finding for Graves' disease, present in >90% of cases.

Graves': Management - Scalpel & Solutions

Medical Options (Context):

  • Antithyroid Drugs (ATDs): Methimazole (MMI preferred), PTU (1st trimester pregnancy/thyroid storm).
  • Radioiodine (RAI): CI: pregnancy, severe GO, malignancy suspicion.
  • Beta-blockers: Symptomatic control.

Surgical Indications:

  • Large goiter (>80g), compressive symptoms.
  • Malignancy suspected/confirmed.
  • ATD failure/intolerance; RAI contraindicated/refused.
  • Moderate-severe active Graves' Orbitopathy (GO).
  • Pregnancy planned <6 months / Rapid biochemical control needed.

Pre-operative Preparation:

  • Achieve euthyroidism: ATDs.
  • Lugol’s Iodine or SSKI: 7-14 days pre-op (↓ vascularity). 📌 "Lugol's Lugs down vascularity".
  • Beta-blockers for symptom control.

Surgical Procedures:

  • Total Thyroidectomy (TT): Preferred, lowest recurrence.
  • Near-Total Thyroidectomy (NTT): Small remnant.

Recurrent and Superior Laryngeal Nerves Anatomy

Key Complications:

  • RLN injury: Hoarseness.
  • Hypoparathyroidism: Hypocalcemia.
  • EBSLN injury: Voice fatigue, ↓ high pitch.
  • Hemorrhage, Hematoma.

⭐ > Total thyroidectomy is preferred for Graves': lowest recurrence, good safety with experience.

High‑Yield Points - ⚡ Biggest Takeaways

  • Graves' disease: Autoimmune; TSH receptor antibodies (TRAb) cause hyperthyroidism, the most common etiology.
  • Specific signs: Exophthalmos, pretibial myxedema, thyroid acropachy, plus diffuse goiter.
  • Diagnosis: ↓TSH, ↑FT4/FT3, +TRAb; diffuse ↑Radioiodine Uptake (RAIU).
  • Surgery: Total/Near-total thyroidectomy for large goiter, ophthalmopathy, or failed medical/RAI therapy.
  • Pre-op: Euthyroidism with antithyroid drugs, then Lugol’s iodine to decrease gland vascularity.
  • Major risks: Recurrent laryngeal nerve injury (hoarseness), hypoparathyroidism (hypocalcemia).

Practice Questions: Graves' Disease

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Preoperative medication of thyrotoxicosis are all except?

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Flashcards: Graves' Disease

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What is the next step in management when a whole-body iodine [I123] scan is positive after a total thyroidectomy for any differentiated thyroid cancer (papillary or follicular carcinoma)?_____

TAP TO REVEAL ANSWER

What is the next step in management when a whole-body iodine [I123] scan is positive after a total thyroidectomy for any differentiated thyroid cancer (papillary or follicular carcinoma)?_____

Radio-iodine ablation [I131]

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