Utility of Sun-reactive Skin Typing and Melanin Index for Discerning Vitamin D Deficiency

BACKGROUND: Skin color, a vitamin D status determinant, can be assessed subjectively by Fitzpatrick sun-reactive skin typing (FST) and objectively by melanin index (MI). FST was validated against MI for discerning vitamin D deficiency [serum 25-hydroxyvitamin D (25(OH)D) <20 ng/ml] in children. METHODS: We measured FST, MI, and serum 25(OH)D in healthy, 8- to 18-year-old children from one of two vitamin D trials. MI from forehead, hand, and upper arm split at the median of the more racially-balanced study cohort and FST (I-III vs. IV-V) were used for discriminating vitamin D deficiency. RESULTS: A total of 296 participants (mean age, 12.3±2.3 yr; black, 208; FST IV-V, 209; 25(OH)D <20 ng/mL, 159) were studied. MI and FST had a strong positive association. Serum 25(OH)D was negatively associated with MI and FST. Sensitivity, specificity, and predictive values were similar for discriminating vitamin D deficiency between higher vs. lower MI and between FST I-III vs. IV-V. ROC AUCs for FST (0.59) and MI (forehead [0.63]; hand [0.62]; arm [0.64]) were similar. CONCLUSIONS: FST is comparable to MI for discerning vitamin D deficiency and can be deemed as an inexpensive, useful surrogate measure of skin color in the context of vitamin D research.