Acanthosis Nigricans Is a Strong Predictor of Low Blood Calcidiol Levels in Children and Adolescents.

Background: Clinical consensus differs as to when blood vitamin D (VD) levels should be measured in children. Obesity and metabolic syndrome are risk factors for low VD levels and are also associated with acanthosis nigricans (AN). Objectives: To test whether the clinical diagnosis of AN is a strong predictor for vitamin D deficiency (VDD) in children. Methods: Within the study period (2015-2020), we identified 677 consecutive individuals (age <18 years) with available calcidiol measurements and compared those with (n = 273) and without (n = 404) AN. Bivariate associations and the occurrence of AN were tested using the chi-squared test. Multivariate logistic regression was performed to control for confounding variables, and adjusted odds ratios with 95% confidence intervals (CI) were reported. Multiple regression analysis was performed, and unstandardized beta coefficients, standard errors, and standardized beta coefficients were reported. Results: Individuals with AN had 3.6 times higher odds of VDD than those without (95% CI: 1.38-9.51, P = 0.009). Males had 0.41 times lower odds of having AN than females (95% CI: 0.21-0.79, P = 0.008). Individuals with vitamin D sufficiency (VDS) were much less likely to be diagnosed with metabolic syndrome compared with those who were vitamin D deficient (P = 0.011), even after adjusting for body mass index z-scores. Conclusion: Children and adolescents with AN are at a higher risk of VDD and should likely be tested for low calcidiol levels.