There is a dearth of data assessing serum
25-hydroxyvitamin D (25[
OH]D) status in
psoriasis. This population-based study in the United States evaluated 25(
OH)D status in
psoriasis and examined the associations between 25(
OH)D and
psoriasis severity. The 2003-2006 National Health and Nutrition Examination Survey was analyzed. Participants aged 20-59 years self-reported
psoriasis,
psoriasis body surface area (BSA), and
psoriasis life impairment (PLI). Serum 25(
OH)D was assessed with the DiaSorin radioimmunoassay. General linear models were used to examine the associations between
psoriasis and 25(
OH)D while accounting for age, gender, race/ethnicity, season, and body mass index (BMI). Among the 5,841 participants with complete data, 148 reported a
psoriasis diagnosis. Mean 25(
OH)D levels and deficiency prevalences (<20 and <30 ng/mL) were not different between those with and without
psoriasis. Among those with
psoriasis, a multivariate model showed participants with BSA >10 hand palms trended towards lower 25(
OH)D compared to those with minimal BSA (-4.98 ng/mL, P = 0.07). PLI was not associated with 25(
OH)D, but BMI showed an inverse association with 25(
OH)D (coefficient = -0.40, P < 0.001). In summary, dermatologists may consider measures of adiposity as better screening tools for
vitamin D deficiency than BSA involvement among psoriatics with mild-to-moderate disease.