AbstractsBackground Thyroid hormones may play a key role in melasma; however, melasma link with thyroid disorders remains controversial.Objectives To compare the serum levels of thyroid-stimulating hormone (TSH), T4, T3, anti-thyroid peroxidase (anti-TPO), and antithyroglobulin between patients with melasma and control group using meta-analysis.Methods We screened 10 databanks and search engines, searched mesh and nonmesh terms. The identified evidences were reviewed and quality assessed using the Newcastle-Ottawa Scale (NOS). The heterogeneity between the primary results was investigated using Cochrane and I-square indices. Random effect model was applied to combine the standardized mean differences of thyroid function indicators between patients with and without melasma. P values meta-analysis was used to investigate the association between anti-TPO and melasma. ResultsWe included seven studies, 473 cases, and 379 controls that had been investigated. The total standardized mean differences (95% confidence intervals) of TSH, T3, T4, and antithyroglobulin antibody between cases and controls were estimated to be 0.33 (0.18, 0.47), À0.01 (À0.20, 0.19), À1.50 (À2.96, À0.04), and 0.62 (0.14, 1.11), respectively. The corresponding figures among women were 0.35 (0.17, 0.52), 0.10 (À0.17, 0.38), À2.75 (À6.30, 0.81), and 0.99 (0.14, 1.83), respectively. P value of metaanalysis showed a significant relationship between anti-TPO serum level and melasma (Fisher = 26.80, P = 0.020).Conclusion Serum levels of TSH, anti-TPO, and antithyroglobulin antibody were significantly higher in patients with melasma than those without melasma. Moreover, these differences were more severe among women with melasma. What is new?• Melasma is an acquired type of hyperpigmentation and might be associated with thyroid disorders.• Results of the present study showed that serum levels of TSH, anti-thyroid peroxidase (anti-TPO), and antithyroglobulin antibody were significantly higher in patients with melasma than those without melasma. Moreover, these differences were more severe among women with melasma.• Serum levels of TSH, anti-TPO, and antithyroglobulin antibodies are associated with melasma, especially among women. Risk of biasThe Newcastle-Ottawa Scale (NOS) checklist was applied to determine the risk of bias in primary studies. This checklist evaluates the studies in three section including selection (four scores), comparability (two scores), and exposure (three scores). Each study was achieved between 0 and 9 scores, and studies with less than five scores were removed from the metaanalysis. The quality assessment was performed by two independent methodologists. 20

The World Health Organization (WHO) has identified depression as the fourth reason of disability in the world, accounting for the greater portion of nonlethal diseases, and predicts it to be the second cause of death by 2020 1-3. In a review study, the prevalence of lifetime depression varied from 1.5 percent in Taiwan to 19 percent in Lebanon. The average in western Germany was 9.2 percent, and in Edmonton in Canada, it was reported at 9.6 percent 1. An international research by the WHO, reported the prevalence of major depression in the general population to be from 1 percent in the Czech Republic to 16.9 percent in the United States, with an average of 8.3 percent in Canada, and up to 9 percent in Chile 1. The average