Subclinical hypothyroidism: an update for primary care physicians

Mayo Clin Proc. 2009;84(1):65-71. doi: 10.1016/S0025-6196(11)60809-4.

Abstract

Subclinical hypothyroidism (SCH), also called mild thyroid failure, is diagnosed when peripheral thyroid hormone levels are within normal reference laboratory range but serum thyroid-stimulating hormone (TSH) levels are mildly elevated. This condition occurs in 3% to 8% of the general population. It is more common in women than men, and its prevalence increases with age. Of patients with SCH, 80% have a serum TSH of less than 10 mIU/L. The most important implication of SCH is high likelihood of progression to clinical hypothyroidism. The possibility that it is a cardiovascular risk factor has been a subject of debate. Large-scale randomized studies are needed for evidence-based recommendations regarding screening for mild thyroid failure and levothyroxine therapy for this condition. Currently, the practical approach is routine levothyroxine therapy for persons with a persistent serum TSH of more than 10.0 mIU/L and individualized therapy for those with a TSH of less than 10.0 mIU/L.

Publication types

  • Review

MeSH terms

  • Diagnosis, Differential
  • Humans
  • Hypothyroidism* / blood
  • Hypothyroidism* / diagnosis
  • Hypothyroidism* / drug therapy
  • Physicians, Family*
  • Practice Guidelines as Topic*
  • Thyrotropin / blood*
  • Thyroxine / therapeutic use*

Substances

  • Thyrotropin
  • Thyroxine