Evaluation of correlation between plasma zinc level and autoimmune and functional thyroid tests in patients with subclinical hypothyroidism

Subclinical hypothyroidism is a relatively common disease with different etiologies. zinc deficiency that is common in Iran is suggested as a potential cause of subclinical hypothyroidism .The aim of this study was the evaluation of the role of plasma zinc in subclinical hypothyroidism.
This cross-sectional study was performed in Mashhad in Khorasan Province between 2009-2010.Atotal of Fifty- seven patients with subclinical hypothyroidism as case group and 57 patients with age- and sex-matched , normal thyroid function were enrolled. Zinc and TSH in controls and TSH, Anti-thyroid peroxidase, free T4 or free T4 index in case group were measured. Results were analyzed with SPSS version 11.5. Based on distribution of variables, parametric and non-parametric tests for comparing means and evaluation of correlation were used.P value less than 0.05 was considered significant.
Mean of plasma zinc was 83 μg/dl in case group and 90 μg/dl in control group and difference between them was statistically significant ( p=0.022) .Frequency of zinc deficiency was 10.5% in case and 14% in control group. There was no statistically significant correlation between plasma zinc level and TSH and Anti-TPO in case group.
There was a negative correlation between zinc level and TSH in patients with subclinical hypothyroidism but this correlation was not statistically significant. So this study does not support the role of plasma zinc in subclinical hypothyroidism.