[Prevalence and clinical characteristics of subclinical hypothyroidism in an opportunistic sample in the population of Castile-León (Spain)].

Objective: To describe the distribution of thyroid-stimulating hormone (TSH) values and to estimate the prevalence of subclinical hypothyroidism in the adult population of Castile and León (Spain).

Method: An observational study was conducted in an opportunistic sample of 45 primary care centers in Castile and León. TSH was determined in people aged ≥35 years that attended a primary care physician and had a blood test for any reason.