Endocrine
Thyroid Disorders — Comprehensive
Endocrine

Thyroid Disorders — Comprehensive

Hyper/hypothyroidism, thyroiditis, thyroid storm, thyroid nodule.

Select any text to highlight it or make a flashcard.

◆Hyperthyroidism causes

  • •Graves disease: TSI antibodies + diffuse goiter + exophthalmos + pretibial myxedema; high RAIU diffuse
  • •Toxic multinodular goiter (Plummer): elderly; nodular uptake on scan
  • •Toxic adenoma: single 'hot' nodule
  • •Painful subacute (de Quervain) thyroiditis: post-viral; tender goiter; transient hyper → hypo → euthyroid; LOW RAIU (released stored hormone)
  • •Painless (silent/postpartum) thyroiditis: similar but no pain; postpartum common
  • •Factitious (exogenous): LOW thyroglobulin (vs all others which are high or normal)

◆Hyperthyroidism management

  • •Methimazole first-line (except first trimester pregnancy — use PTU)
  • •PTU also used in thyroid storm (blocks T4→T3 conversion)
  • •Radioactive iodine ablation: definitive; avoid in pregnancy/breastfeeding/severe ophthalmopathy
  • •Thyroidectomy: large goiter, ophthalmopathy, pregnancy
  • •β-blocker for symptoms (propranolol)

◆Thyroid storm

  • •Severe hyperthyroidism + fever + tachycardia + agitation/coma + GI symptoms
  • •Triggers: surgery, infection, iodine load, parturition
  • •Burch-Wartofsky score for diagnosis
  • •Treatment ORDER matters:
  • •1. β-blocker (propranolol) — symptoms
  • •2. PTU or methimazole — blocks new hormone synthesis
  • •3. Iodine (Lugol) ≥1 hr AFTER PTU (Wolff-Chaikoff)
  • •4. Glucocorticoid (hydrocortisone) — blocks T4→T3 conversion + treats possible adrenal insufficiency
  • •Cooling, IV fluids, treat precipitant

◆Hypothyroidism

  • •Hashimoto thyroiditis: most common cause; anti-TPO + anti-thyroglobulin antibodies; ↑ TSH + ↓ free T4; goiter
  • •Other: post-RAI/surgery, iodine deficiency, lithium, amiodarone, congenital
  • •Subclinical: ↑TSH + normal T4 — treat if TSH >10, symptomatic, or trying to conceive
  • •Treatment: levothyroxine; pregnancy increases dose ~30%

◆Myxedema coma

  • •Severe hypothyroidism + AMS + hypothermia + hypoventilation + bradycardia
  • •IV levothyroxine + IV hydrocortisone (until adrenal insufficiency excluded) + supportive

◆Thyroid cancer

  • •Papillary (#1, best prognosis): psammoma bodies + 'Orphan Annie' nuclei; spreads via lymph; thyroidectomy
  • •Follicular: hematogenous spread (bone, lung)
  • •Medullary: from parafollicular C cells; ↑calcitonin; MEN 2A/2B
  • •Anaplastic: elderly; rapidly progressive; poor prognosis

High-yield pearls

  • ◆PTU = Pregnancy (first trimester) + Thyroid storm (blocks T4→T3); methimazole otherwise
  • ◆Iodine in thyroid storm must come AFTER thionamide to avoid Jod-Basedow + Wolff-Chaikoff
  • ◆Low RAIU + hyperthyroid = thyroiditis, exogenous hormone, iodine load
  • ◆Pregnancy + Graves → PTU (1st trimester) → methimazole (2nd/3rd)
  • ◆Amiodarone = iodine-rich → can cause hyper or hypothyroid; monitor TFTs
  • ◆Hashimoto: 80x risk of thyroid lymphoma
Done reading?
Track your progress by marking this complete.
Next in Endocrine