Effects of light to moderate alcohol consumption on thyroid volume and thyroid function

Objective To examine a possible relationship between alcohol consumption and thyroid volume and function.

Subjects A total of 1493 subjects (599 males aged 45–60 years and 894 females aged 35–60 years) with no known thyroid disorders who were participating in the SUpplémentation en VItamines et Minéraux AntioXydants (SU.VI.MAX) study.

Measures Daily dietary intakes and alcohol consumption in grams per day were based on five 24-h dietary records. Thyroid volume and structure were measured by ultrasonography. At baseline, TSH and free T4 (FT4) were measured.

Results Male and female drinkers consumed (mean ± SD), respectively, 30·6 ± 23·3 and 14·2 ± 13·4 g of ethanol per day. There was a decrease in carbohydrate intake with higher alcohol consumption among both male (P = 0·0001) and female drinkers (P = 0·06). Alcohol intake was associated with higher thyroid volume in males and females independently of iodine status. Multivariate odds ratios (ORs, with 95% confidence intervals) of thyroid enlargement (sex-specific 85th percentile values of ≥ 20 ml for males, ≥ 14 ml for females) in males and females who drank ≥ 45 and ≥ 20 g/day, respectively, were 2·22 (1·10–4·47) and 2·11 (1·15–3·90) compared with low drinkers, and 11·75 (2·15–64·12) and 2·03 (1·04–3·96) compared with abstainers. ORs were slightly increased when smokers were excluded. Alcohol intake was associated with low FT4 levels in male drinkers independently of TSH.

Conclusions An increasing dose–response relationship was found between alcohol intake levels and ORs for thyroid enlargement in both males and females. Alcohol consumption was strongly associated with a higher risk in females.