Seasonal and regional variations of asthma and association with osteoporosis: possible role of vitamin D in asthma.
Background. Based on the evidence that vitamin D is involved in the development of immune system and vitamin D receptor gene is associated with asthma, we supposed that vitamin D is related to the development of asthma. Methods. Asthma patients were identified from the Swedish Hospital Discharge Register and the hospitalization rate was examined by different seasons and regions. Standardized incid