Objective: Hypothyroidism is the most common condition linked to a hormone deficiency, nevertheless data on its prevalence are scarce in Spain. For that reason, we have estimated its prevalence through the registration of patients who had used thyroid hormones in Andalusia (South Spain).
Methods: Data of patients who had withdrawn levothyroxine under the public system during 2014 from the base of the Andalusian Health Service were considered. Prevalence were calculated with confidence intervals of 95% for each management area, stratified by sex and age groups, and differences between them were evaluated.
Results: 321,368 people (98% older than 18 years and 83% female) were identified as levothyroxine users and a prevalence of hypothyroidism of 3.95% (95%CI:3.94-3.96) was estimated for the general population. The condition was more common in females, in the older 18 years 7.81% (95%CI:7.80 to 7.82) compared to males 1.75% (95%CI:1.73-1.77) with a ratio of 4.5-fold. It increases in the population of women older than 45 years, 10.32% (95%CI:10.30-0.32) and in the over 60 years 11.37% (95%CI: 11.35-11.40). The prevalence in adult women in the western provinces is 7.38% (95%CI:7.36-7.40), in the eastern provinces 8.59% (95%CI:8.57-8.62) and in coastal areas 6.70% (95%CI: 6.68-6.72) compared to the mountainous ones, which is 8.91% (95%CI:8.88-8.94).
Conclusions: The results denote a high prevalence of hypothyroidism in the adult population of Andalusia compared to the nearby countries, with a clear increased associated with females and age. Furthermore, the prevalence of the illness presents also a geographically-related variability.
Keywords: Geographic Factors; Hypothyroidism; Pharmacoepidemiology; Prevalence; Sex Ratio; Spain; Thyroxine.