Inflammatory processes of the respiratory tract are associated
with up regulation of both cough hyperactivity and bronchial
hyperactivity and may lead to asthma or be associated
with chronic cough. In nutritional rickets, Vitamin D has been
shown to influence allergy-mediating immune cells such as T
cells suggesting that vitamin D plays a role in allergy development.
In children, lower 25(OH)D serum levels are associated
with increased risks for allergic diseases [24, 25].
Zitterman et al. demonstrated an association between vitamin
D deficiency and allergic diseases [26]. Vitamin D deficiency
was found to increase the risk of allergic diseases in children
such as asthma [27]. In the present study authors found an
association between allergy history, family history of allergic
diseases and serum vitamin D levels. Allergy history and family
history of allergic diseases were found higher in RRI and
chronic cough group than control group.VitaminD deficiency
may be common in children with allergic diseases. Supporting
this notion, authors also found that serum 25(OH)D levels in
children having chronic cough with positive allergy history
were lower than children having chronic cough without allergy
history. It is important to follow up children with history of
chronic cough for developing allergic diseases.