Familial Aggregation in Vitamin D Deficiency Disorder.

Introduction The relationship between vitamin D deficiency and some diseases (i.e., heart diseases, malignancies, and infectious diseases) has extensively been studied. There is, however, no epidemiological report on whether the familial predisposing factors have any role in the occurrence of vitamin D deficiency. The aim of this study was to investigate the familial aggregation of vitamin D deficiency disorder in the northwest region of Iran. Materials and Methods A total number of 930 individuals from the general population were invited/registered to the Family Medicine Clinic of Asadabadi Hospital, Tabriz University of Medical Sciences, Iran. A blood sample was obtained from subjects to measure the level of vitamin D. The blood tests were carried out by the enzyme-linked immunosorbent assay method using Biorexfars diagnostics in the Asadabadi Hospital Laboratory. We calculated odds ratio (OR) with 95% confidence intervals (95% CI) to estimate the aggregation of vitamin D deficiency among relatives. Results We ascertained 580 cases with vitamin D deficiency disorder representing an overall prevalence rate of 62.4% (95% CI: 59-65%) in the northwest region. An aggregation of the vitamin D deficiency was found among brothers (OR = 1.55, 95% CI: 0.72-3.32), sisters (OR = 1.24, 95% CI: 0.80-1.93), and spouses (OR = 1.18, 95% CI: 0.76-1.82) of the cases. Other relatives (including parents, grandparents, grandchildren, aunts, nieces, and nephews) showed no aggregation of deficiency in the family in this study. Conclusion Our findings indicated that there might be an aggregational occurrence of vitamin D deficiency in some of the family members. Therefore, to be able to perform early preventive intervention, we would suggest testing the blood level of vitamin D for brothers, sisters, and spouse if one was diagnosed as having vitamin D deficiency.