Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 48 4 2019 04 16 644 654 Dariush D. FARHUD School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Department of Basic Sciences/Ethics, Iranian Academy of Medical Sciences, Tehran, Iran AND Farhud Genetic Clinic, Tehran, Iran Atefeh MEHRABI Farhud Genetic Clinic, Tehran, Iran and School of Advanced Medical Sciences, Islamic Azad University, Tehran Medical Branch, Tehran, Iran Abdolfattah SARAFNEJAD Noor Pathobiology Laboratory, Tehran, Iran and Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Hamid Reza SADEGHIPOUR Noor Pathobiology Laboratory, Tehran, Iran and Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Abbas RAHIMIFOROUSHANI Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammdad Bagher ROKNI School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Keyvan MAJIDI Noor Pathobiology Laboratory, Tehran, Iran Ahad ALIZADEH Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Marjan ZARIF-YEGANEH Farhud Genetic Clinic, Tehran, Iran and Cellular and Molecular Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Maryam JALALI Noor Pathobiology Laboratory, Tehran, Iran Mahmoud JALALI Noor Pathobiology Laboratory, Tehran, Iran and Department of Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Ali Akbar AMIR ZARGAR Noor Pathobiology Laboratory, Tehran, Iran and Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Farideh KHOSRAVI Noor Pathobiology Laboratory, Tehran, Iran and Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Amir MOMENI Booali Pathobiology Laboratory, Qom, Iran Mohammad KHAZENI Noor Pathobiology Laboratory, Tehran, Iran and Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Asadallah HENDIANI Booali Pathobiology Laboratory, Qom, Iran Mehdi AHMADI Booali Pathobiology Laboratory, Qom, Iran Alireza DEHSHIRI Booali Pathobiology Laboratory, Qom, Iran Payam RASOOLI Payvand Teb va Narmafzar Company (PTN), Tehran, Iran 2019 04 16 Background: Vitamin D is an essential substance for absorption of calcium and phosphorus from intestine so it is vital for muscles and skeletal development. Deficiency of this vitamin is pandemic. The vitamin D status depends on the different factors such as UV exposure, diet, and ecological features of living location, age and gender. The aim of this study was to describe the vitamin D level in different provinces of Iran and to investigate the association between vitamin D status and multiple variables. Methods: We collected the serum 25(OH)D (Vitamin D) level data of 308,005 people referred to different laboratories from 30 provinces of Iran and organized them by each province, year, age, gender, precipitation, latitude and longitude, and humidity over 10 yr (2009-2018). Data were analyzed to find out the correlation between age, gender, longitude and latitude, humidity and sum of precipitation. Results: West Azerbaijan had the highest level of vitamin D with a mean level of 33.24 and a standard deviation of 32.001, and North Khorasan had the lowest level with a mean level of 14.46 and a standard deviation of 8.980 among 30 provinces of Iran. The correlation between all studied variables (age, and gender, latitude and longitude, humidity, the sum of precipitation) was significant (P<0.001). Conclusion: The average total vitamin D level in Iran is 25.41 ng/ml, which is within the area of deficiency. Vitamin D is associated with age, and gender, latitude and longitude, humidity, the sum of precipitation. So changes in any of these variables can lead to vitamin D alteration.     https://ijph.tums.ac.ir/index.php/ijph/article/view/16854 https://ijph.tums.ac.ir/index.php/ijph/article/download/16854/6351