• Credits

  • Section Writer: Dr. Om J Lakhani
  • Section Editor: Dr. Om J Lakhani

• Q. What is the difference between thyrotoxicosis and hyperthyroidism ?

  • Thyrotoxicosis is an umbrella term that refers to the increase of thyroid hormone levels (T3 and T4) in circulation and the resultant clinical signs and symptoms of the same.
  • Thyrotoxicosis can be subdivided into Hyperthyroidism, Destructive thyroiditis and ectopic thyroid hormone production
    • Hyperthyroidism refers to increase thyroid hormone production by the thyroid gland leading to thyrotoxicosis.
      • This is usually associated with increased radioactive iodine uptake
    • Destructive thyroiditis is the relase of the preformed and stored thyroid hormones into the circulation as a result of damage to the thyroid follicles
      • This is usually associated with reduced radioactive iodine uptake
    • Ectopic thyroid hormone production is the production of thyroid hormone in from other organs of the body other than the thyroid gland which may be added to the normal thyroid hormone pool leading to thyrotoxicosis.
      • This is also associated with reduced radioactive iodine uptake

#Clinicalpearl
- "All patients with hyperthyroidism have thyrotoxicosis but all patients with thyrotoxicosis may not have hyperthyroidism"

• Q. Enlist the cause of thyrotoxicosis

  • Hyperthyroidism with a normal or high radioiodine uptake
    • Autoimmune thyroid disease
      • Graves' disease
      • Hashitoxicosis
    • Autonomous thyroid tissue
      • Toxic adenoma
      • Toxic multinodular goiter
    • TSH-mediated hyperthyroidism
      • TSH-producing pituitary adenoma
      • Non-neoplastic TSH-mediated hyperthyroidism
    • Human chorionic gonadotropin-mediated hyperthyroidism
      • Hyperemesis gravidarum (Gestational thyrotoxicosis)
      • Trophoblastic disease
  • Hyperthyroidism with a near absent radioiodine uptake
    • Thyroiditis
      • Subacute granulomatous (de Quervain's) thyroiditis
      • Painless thyroiditis (silent thyroiditis, lymphocytic thyroiditis)
      • Postpartum thyroiditis
      • Amiodarone (also may cause iodine-induced hyperthyroidism)
      • Radiation thyroiditis
      • Palpation thyroiditis
    • Exogenous thyroid hormone intake
      • Excessive replacement therapy
      • Intentional suppressive therapy
      • Factitious hyperthyroidism
    • Ectopic hyperthyroidism
      • Struma ovarii
      • Metastatic follicular thyroid cancer

• Q. Is it required to perform a thyroid scan in patients patients with thyrotoxicosis ?

  • While etiological evaluation for thyrotoxicosis is required in all cases, Graves' disease is the most common cause of thyrotoxicosis
  • Patients can be clinically diagnosed to have Graves' disease when they have the following:
    • Long duration of symptoms
    • Thyroid associated orbitopathy
    • Diffuse goiter (with bruit)
  • It is prudent to perform a thyroid scan in the following group of patients
    • Recent onset of thyrotoxicosis (short duration of symptoms)
    • Absence of thyroid associated orbitopathy
    • Presence of a nodular goiter

#Updates

• Date: Sunday, 18 April 2021
• Source: YouTube video: Thyrotoxicosis management issues by Dr. Om J Lakhani

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