Because exposure to UV radiation accounts for a significant portion of endogenous vitamin D production, cutaneous lupus (CLE) subjects practicing sun-protective measures are at risk for vitamin D insufficiency. Previous studies have shown light-skinned CLE subjects to have lower serum 25-hydroxy (25-OH) vitamin D levels than normal controls.
To assess the status of vitamin D insufficiency in dark-skinned CLE individuals.
We performed a cross-sectional study comparing serum 25-OH vitamin D levels in 25 CLE and 26 normal African American (AA) age-, gender-, and season-matched subjects in Dallas, Texas. A questionnaire on demographics, medical history, and lifestyle habits was administered to determine factors potentially affecting vitamin D levels. Findings were contrasted to a similar comparison in 26 CLE and 24 age-, gender-, and season-matched normal Caucasian and Hispanic (C/H) subjects.
We found similar 25-OH vitamin D levels in CLE (52.0±18.5 nmol/L) and normal AA subjects (54.8±21.2 nmol/L) (p = 0.62). Almost half of AA subjects in both groups were vitamin D-insufficient. A larger gap in 25-OH vitamin D levels was found in C/H CLE (59.4±21.0 nmol/L) and normal subjects (70.5±27.4 nmol/L) (p = 0.12). Two-way ANOVA analysis demonstrated that skin color (AA vs. C/H) had a significant effect on 25-OH vitamin D levels (p = 0.008), though CLE status (CLE vs. normal) did not (p = 0.13).
Providers are encouraged to address vitamin D insufficiency concerns in all dark-skinned individuals. Future studies should stratify subjects by skin color in determining differences between CLE and normal controls.