TSH reference limits: New concepts and implications for diagnosis of subclinical hypothyroidism

摘要

I wrote this Commentary to provide perspective on controversies that surround determination of reference limits for thyroid-stimulating hormone (TSH), particularly the upper limit. New findings have changed the conceptual basis of TSH distribution and consequent reference limits for people of different ages and race/ethnicities. They significantly influence the diagnosis of subclinical hypo-thyroidism (SCH) and the management of hypothyroidism in the expanding geriatric population, which necessitates changes in endocrine practice in older patients.