Alcohol consumption is associated with reduced prevalence of goitre and solitary thyroid nodules

OBJECTIVE Goitre prevalence is dependent on iodine intake and smoking habit s, but further risk factors have only been examined briefly. We examined th e association between alcohol consumption and the prevalence of thyroid enl argement and nodularity. DESIGN Cross-sectional population study with ultrasonography of the thyroid gland and assessment of alcohol intake and smoking habits from questionnai res. SUBJECTS Four thousand six-hundred and forty-nine men and women aged 18-65 years, randomly selected from the Danish Civil Registration System. MEASUREMENTS Thyroid volume and prevalence of thyroid enlargement, multiple nodules or a solitary nodule in the thyroid. RESULTS Abstainers and participants with a low alcohol consumption (< 7 dri nks/week) had the same prevalence of thyroid enlargement and nodularity, bu t participants with moderate (8-28 drinks/week for women, 8-42 for men) or high (> 28/42 drinks/week) alcohol consumption had much lower prevalence of thyroid abnormalities. Possible confounding by sex, age, iodine status and smoking was considered in all models. Odds ratios compared to abstainers f or thyroid enlargement were 0.74 [95% confidence interval (CI) 0.57-0.96] f or moderate- and 0.44 (95% Cl 0.22-0.88) for high alcohol consumption. Odds ratios compared to abstainers for a solitary nodule were 0.64 (95% Cl 0.42 -0.96) for moderate- and 0.41 (95% Cl 0.12-1.37) for high alcohol consumpti on. Mean thyroid volume was 13.5 ml among abstainers compared to 10.9 ml am ong participants with high alcohol consumption (P < 0.001). Both wine- and beer consumption were associated to lower prevalence of thyroid abnormaliti es. CONCLUSIONS Increasing levels of alcohol consumption were associated to low er prevalence of thyroid enlargement and to lower prevalence of a solitary nodule in the thyroid, and indications of a causal relationship were found.