Abstract Background: Hidradenitis suppurativa is a chronic inflammatory skin disease of terminal follicular acroinfundibulum. Objectives: This study aimed to evaluate serum irisin, plasma glucose, insulin, and lipid levels in hidradenitis suppurativa, and elucidate possible associations with disease activity, inflammatory, or metabolic parameters. Methods: This case-control study included 37 patients (M/F: 9/28) and 37 sex-, age- and body mass index -matched healthy controls (M/F: 11/26). Demographic data, Hurley stage of disease, fasting glucose, insulin, total cholesterol, high density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, C-reactive protein levels, erythrocyte sedimentation rate, hematologic parameters, and serum irisin were assessed. Results: The hidradenitis suppurativa group had significantly higher waist circumference than controls (p < 0.001). Insulin resistance, defined as a homeostatic model assessment for insulin resistance value greater than 2.5, was observed in 45.9% of patients and 8.1% of controls (p = 0.003), whereas metabolic syndrome was observed in 32.4% of patients and 5.4% of controls (p < 0.001). Furthermore, plasma triglycerids, glucose, and insulin levels were significantly higher in the hidradenitis suppurativa (p = 0.013, p = 0.001, and p = 0.004), respectively. Mean irisin level was insignificantly higher in the hidradenitis suppurativa group (37.4 ± 32.6) than in controls (26.2 ± 24.7, p = 0.217). Study limitation: Physical activity and the exercise levels of participants were not documented. Conclusion: This study indicates that hidradenitis suppurativa patients have higher serum irisin, fasting plasma glucose, insulin, and triglycerides levels than healthy controls. Thus, the authors suggest that hidradenitis suppurativa patients should be evaluated for insulin resistance and metabolic syndrome, and monitored accordingly.

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.