THE ASSOCIATION of anemia with primary hypothyroidism is well known [1,2] since the prevalence of anemia in patients with hypothyroidism has been shown to be high (20-60%) [3]. Hypothyroidism is much more frequently observed in women than men [4], in the former particularly between puberty and menopause [5], while the prevalence of anemia is also known to be higher for women than men [6] since menstruation is an acknowledged cause of anemia in women. In fact, previous studies reported that the higher percentage of anemia among women with hypothyroidism might be linked to menorrhagia [2,3]. Therefore, the evidence of the association between thyroid function and anemia was limited since the study populations included Endocrine Journal 2013, 60 (9), [1029][1030][1031][1032][1033][1034] Free thyroxine (FT4) and anemia in relation to drinking status of Japanese men: The Nagasaki islands study Abstract. It is well known that hypothyroidism is associated with anemia. It has also been reported that alcohol consumption may affect thyroid function. Furthermore, hemoglobin levels of drinkers are reportedly higher than those of non-drinkers. However, no published study has investigated the association between thyroid function evaluated with the free thyroxine (FT4) test and anemia while taking drinking status into account. We conducted a cross-sectional study of 843 men aged 30-89 years undergoing general health checks. While no significant associations were noted between FT4 and anemia for total subjects, when the analysis was limited to non-drinkers, a significant association was observed. After adjustment for classical cardiovascular risk factors and thyroid stimulating hormones (TSH), adjusted odds ratio (OR) and 95% confidence interval (CI) for an increment of 1SD (standard deviation) for FT4 (0.17 ng/dL) for anemia were 0.85 (0.67-1.09) for total subjects, 0.59 (0.41-0.85) for non-drinkers, and 1.23 (0.83-1.83) for drinkers. In conclusion, FT4 is inversely associated with anemia for non-drinking but not for drinking men. However, drinking may act as a confounding factor for this association.Key words: FT4, Anemia, Non-drinker, Men women. Furthermore, previous studies reported that light to moderate alcohol consumption might affect thyroid function [7] and that hemoglobin levels of drinkers were higher than those of non-drinkers [8,9]. Since the prevalence of drinkers is high among Japanese men [10], a study to investigate the association between thyroid function and anemia among Japanese men should take drinking status into account. To investigate those associations we conducted a cross-sectional study of Japanese men aged 30-89 years.