1. Limit testing for thyroid disease to appropriate patients, namely those with a significant pre-test probability of abnormal results, such as:
    • those with classic signs or symptoms of thyroid disease.
    • those whose symptoms or signs are not classic, but who are at a higher risk for disease (e.g., the elderly, postpartum women, those with a history of atrial fibrillation, those with other endocrine disorders).
  2. In patients with established thyroid disease, do not check thyroid-stimulating hormone levels too often, but rather test at the appropriate times, such as:
    • after changing medical doses.
    • when following patients with mild disease before initiating treatment.
    • periodically in stable patients receiving treatment.
  3. When examining the thyroid gland, use proper technique (i.e., from behind the patient, ask the patient to swallow), especially to find nodules (which may require further investigation).

Risk Factors for Thyroid Disease

  • Women >45yo
  • Postpartum
    • No clear impact (benefit or harm) for universal screening in pregnancy
  • Radiation
  • Drug-induced (lithium, amiodarone)
    • Lithium can cause goiter, hypothyroidism (more common), hyperthyroidism
    • Interferon alfa-2b may cause hypothyroidism or hyperthyroidism
  • Autoimmune disease (eg. DM1)
  • Strong family history of thyroid disease



  • Mood: Depression
  • Memory
  • Motor: Fatigue/Lethargy
  • Mass: Weight gain
  • Metabolism: Cold intolerance
  • Menstrual irregularities
  • Constipation
  • Dry skin


  • Palpitations/ tachycardia/ atrial fibrillation
  • Widened pulse pressure
  • Nervousness and tremor
  • Heat intolerance
  • Weight loss
  • Muscular weakness
  • Usually goiter is present


  • TSH
    • TSH high (>4-5mU/L) - Possible Primary Hypothyroidism
      • FT4 to determine degree of hypothyroidism
      • Anti-TPO Ab once
    • TSH low (<0.2mU/L) - Possible Primary Hyperthyroidism
      • Free T4 and T3 to determine degree of hyperthyroidism
      • If no obvious cause (eg. Graves - new ophthalmopathy, goiter)
        • Thyrotropin receptor antibodies (TRAb)
        • Radioactive iodine uptake (contraindicated in pregnant/breastfeeding)
        • Ultrasound with thyroidal blood flow
  • Thyroid ultrasound (if abnormal thyroid size, nodules)
      • FNA for nodules >1cm or 5mm and suspicious features (r/o cancer)



  • Primary
    • Chronic autoimmune thyroiditis
    • Iatrogenic (thyroidectomy, radioiodine therapy, external radiation)
    • Iodine deficiency/excess
    • Drugs - thionamides, lithium, amiodarone, interferon-alfa, interleukin-2, perchlorate, tyrosine kinase inhibitors
    • Infiltrative diseases (fibrous thyroiditis, hemochromatosis, sarcoidosis)
    • Transient hypothyroidism
      • Thyroiditis (silent lymphocytic, subacute granulomatous, postpartum)
      • Subtotal thyroidectomy
      • Radioiodine therapy for Graves'
      • Withdrawal of suppressive doses of thyroid hormone in euthyroid patients
    • Congenital thyroid disease
  • Central
    • TSH deficiency
    • TRH deficiency
  • Generalized thyroid hormone resistance


  • Normal/high radioiodine uptake
    • Autoimmune
      • Graves' disease
      • Hashitoxicosis
    • Autonomous thyroid tissue
      • Toxic adenoma
      • Toxic multinodular goiter
    • TSH-mediated
      • Pituitary adenoma
    • Human chorionic gonadotropin
      • Hyperemesis gravidarum
      • Trophoblastic
  • Near absent radioiodine uptake
    • Thyroiditis
      • Subacute granulomatous (de Quervain's) thyroiditis
      • Painless thyroiditis (silent, lymphocytic, postpartum)
      • Amiodarone
      • Radiation thyroiditis
      • Palpation thyroiditis
    • Exogenous thyroid hormone intake (excessive replacement therapy)
    • Ectopic hyperthyroidism
      • Struma ovarii
      • Metastatic follicular thyroid cancer


  • Subclinical hypothyroidism (possible CAD, heart failure, stroke, lipids, infertility)
    • Consider treatment if TSH≥20mU/L (BMJ 2019), symptomatic, or risk (elevated Anti-TPO Ab, Goiter, strong family history of autoimmune, pregnancy)
    • Consider treatment in infertility
  • Subclinical hyperthyroidism (risk of atrial fibrillation/flutter, heart failure, lower BMD)
    • Consider treatment if TSH <0.1 mIU/L and
      • Symptomatic (palpitations, tremor, nervousness)
      • >65yo
      • Comorbidities such as heart disease or osteoporosis
      • Postmenopausal (<65yo) and not taking estrogen/bisphosphonates

Treatment of Hypothyroidism

  • Subacute granulomatous thyroiditis (viral infection, painful thyroid) - NSAIDs
  • Levothyroxine treatment of choice, start 12.5-50mcg/day
    • No strong evidence for alternatives (levothyroixine-liothyronine or thyroid extract therapy)
    • Target TSH euthyroid range (except in secondary hypothyroidism, where target FT4)
      • No evidence for levothyroxine in euthyroid (except in thyroid cancer target undetectable TSH to reduce recurrence by 40%)
      • Avoid TSH <0.1mIU/L
        • Risk of thyrotoxicosis - A-fib and osteoporosis
      • Consider higher serum TSH target in elderly and hospitalized (eg. 8)


  • Repeat TSH q3-4 months until stable, then yearly
    • If dose higher than expected, evaluate for GI disorder (H pylori gastritis, atrophic gastritis, celiac)
  • Follow serum TSH when started on medications, change in body weight, aging, pregnancy
  • Poor adherence, weekly levothyroxine should be considered

Myxedema coma

  • Altered mental status, hypoventilation, hypothermia, hypotension, bradycardia, hyponatremia, hypoglycemia
  • Treat aggressively (mortality 40%)
    • Levothyroxine (T4) loading dose 200-400mcg IV, then 1.6mcg/kg/day IV
    • Liothyronine (T3) 5-20mcg followed by 2.5-10mcg q8h given with T4
    • Glucocorticoids (hydrocortisone 100mg IV q8-12h x2d) until coexisting adrenal insufficiency can be excluded
    • Supportive measures (ventilation, fluids, correction of hyponatremia and hypothermia)

Treatment Hyperthyroidism

  • Primary vs. Secondary (TSH/T4)
    • Elevated TSH, rule out pituitary gland tumour
    • Low TSH, consider radioiodine uptake scan
      • Graves (TSH receptor antibodies=TRAb)
        • Thionamides (Methimazole - MMI or Propylthiouracil - PTU)
          • Mild hyperthyroidism, can start MMI at 5-10mg PO daily
            • WBC (ANC) and LFT prior to starting MMI
            • Repeat TSH/T4/T3 every six weeks
              • Once T4/T3 normalized, can decrease dose MMI dose by 30-50%
              • Once TSH/T4 normal can change labs to q6 months
            • Can stop MMI if TRAb and TSH normal after 12-18 months of therapy
              • If persistently high TRAb, consider continuing MMI or radioiodine/sugery
        • Beta-blockers (for symptom control)
          • Atenolol 25-50mg daily (up to 200mg) until goal HR<90
        • Ophthalmopathy: Steroids, radiation, surgical decompression
      • Thyroiditis
        • NSAIDs, steroids
        • Beta-blockers for symptomatic treatment
      • Toxic adenoma/multinodular goiter
        • First-line: Radioiodine or surgery
          • May consider thionamide initially for short-term
        • Beta-blockers for symptomatic treatment

Thyroid storm

  • Hyperthermia, tachycardia, N/V/D, dehydration, delirium, coma
  • Causes: Trauma, surgery, RAI
  • Treatment
    • B-Blockers (Propranolol 60-80mg q4-6h)
    • PTU 200mg PO q4h
    • Iodine solution (delayed 1h after PTU)
    • Iodinated radiocontrast
    • High-dose IV hydrocortisone 100mg IV q8h