Background: Organ transplant recipients (OTR) have an increased risk of non-melanoma skin cancer (NMSC) and are advised to avoid direct sunlight. OTR living in the Nordic countries are especially vulnerable to hypovitaminosis D as vitamin D production in the skin is restricted to the summer months.
Objectives: To investigate constitutional and external factors predicting hypovitaminosis and seasonal variation of vitamin D in renal transplant recipients (RTR) living in the vicinity of Oslo (59(o) N).
Methods: Ninety-four RTR were included. Interviews covering dietary intake of vitamin D and sun exposure were performed and blood samples were collected in February and August 2013. Results Mean age of patients was 56.8 years and mean graft age 14.5 years. The mean daily total vitamin D intake was 11.8 μg, and the prevalence of hypovitaminosis D (<75 nmol/L) was 67.0% in winter and 56.4% in summer. Sunscreen users had significantly higher 25(OH)D than non-users (p = 0.03). Excluding patients having travelled to southern latitudes during the last three months before blood sampling, no statistical difference was found between winter and summer values of vitamin D (p = 0.60). Being male or having red/light blond hair colour increased vitamin D values significantly from winter to summer.
Conclusions: Hypovitaminosis D is relatively frequent in Norwegian RTR but not as frequent as earlier reported in studies of RTR from lower latitudes. Lack of seasonal variation in vitamin D may be explained by sun protective behaviour and high dietary intake of vitamin D among patients in this study.
Keywords: Non-melanoma skin cancer; Vitamin D; organ transplant recipients; renal transplant recipients; seasonal variation vitamin D; skin cancer.