RESUMO
Abstract: Background: Recent studies that investigated the effect of vitamin D on skin cancer risk have exhibited inconsistent results. Objective: The aim of the study was to evaluate vitamin D status in patients with actinic keratosis. Methods: A cross-sectional study was conducted on 31 patients with actinic keratosis and 29 healthy controls. Serum vitamin D levels in the study group were determined by liquid chromatography/tandem mass spectrometry. Results: Serum 25(OH)D levels in patients with actinic keratosis were significantly higher than those of the healthy controls (P=0.04). Prevalence of 25(OH)D deficiency was significantly higher in the healthy controls (75.9%) compared to the patients with actinic keratosis (54.8%), but the difference was not statistically significant (P= 0.09). Study limitations: The cross-sectional design of the study, data on smoking based on patient self-report, and subjects' different dietary habits, which can influence 25(OH)D levels, are the study's limitations. Conclusion: Serum vitamin D level can be used as a marker for ultraviolet B radiation from sun exposure; therefore, it can be used in individuals at risk of actinic keratosis. Oral intake of vitamin D through diet or supplements is proposed instead of prolonged ultraviolet exposure to maintain adequate vitamin D serum levels. Further research is needed to elucidate the role of vitamin D in skin carcinogenesis.