Hypothyroidism, Acquired



Hypothyroidism that occurs after the neonatal period


  • May develop at any age
  • Autoimmune thyroid disorders occur more frequently in children and adolescents with type 1 diabetes and other autoimmune conditions.
  • Chronic lymphocytic thyroiditis prevalence correlates with iodine intake; countries with the highest dietary iodine also have the highest prevalence.
  • Subclinical hypothyroidism (TSH concentration between the upper limit of normal reference range and 10 mIU/L, with normal free thyroxine level) found in 7–23% of obese children and 0.3–2% of normal weight controls. It seems to be a consequence rather than cause of the obesity and can normalize with weight loss.

Risk Factors


  • Family history of thyroid disease or other autoimmune endocrinopathies increases risk.
  • Genetic predisposition in patients with chronic lymphocytic thyroiditis; 30–40% of patients have a family history of thyroid disease, and up to 50% of their 1st-degree relatives have thyroid antibodies.
  • Weak associations of chronic lymphocytic thyroiditis with certain human leukocyte antigen haplotypes; also associated with genotypes of cytotoxic T lymphocyte–associated 4 (CTLA4) and interleukin-18 (IL-18) genes.
  • Autoimmune thyroid disease may be part of type II autoimmune polyglandular syndrome (Schmidt disease).
  • Genetic syndromes associated with higher incidence of autoimmune thyroiditis:
    • Down syndrome
    • Turner syndrome (especially those with isochromosome Xq)


  • Myriad causes (see “Differential Diagnosis”)
  • Can result from thyroid gland dysfunction (primary hypothyroidism) or from pituitary/hypothalamic dysfunction leading to understimulation of the thyroid gland (secondary and tertiary hypothyroidism)

Commonly Associated Conditions

  • Type 1 diabetes
  • Other autoimmune conditions
  • Pernicious anemia
  • Vitiligo
  • Alopecia areata
  • Obesity

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