The Role of Season and Climate in the Incidence of Congenital Hypothyroidism in Kerman Province, Southeastern Iran

Abstract

Objective: Congenital hypothyroidism (CH) is a common endocrine disease and an important cause of mental retardation. The purpose of this study was to investigate the probable role of season and climatic factors in the incidence of CH in Kerman Province, Iran which has various climates. Methods: Incidence data were collected from the CH screening program files from 2005 – 2011 in Kerman Province, Iran. Climate data was collected from the Kerman Province Meteorological Office. Data were analyzed using R version 3.0.2 and Minitab16 soft wares. The relations were tested by Negative binomial Regression and time series trend analysis. Results: The overall incidence of CH in Kerman was 2.7 per 1000 births. A similar pattern between CH incidence and temperature, humidity and rainfall was not observed in different cities with different climates. Changes in the incidence of hypothyroidism fitted a quadratic trend time series model. It is expected that the incidence of CH declines in the next 10 years. Conclusions: It seems like there is no relation between CH incidence and climate factors. Other world studies have not confirmed a specific pattern either.