Vitamin D deficiency in urban indigent patients in Southern California.

Objective: To determine the prevalence of 25-hydroxy (OH) vitamin D deficiency in ambulatory and hospitalized patients from a large urban county medical center in Southern California, and assess the effects of season, ethnicity, age, location of care, and comorbidities on prevalence. Methods: Data for all serum 25(OH)-D2 and -D3 concentrations measured during 2010, along with associated demographic characteristics and comorbidity data, were analyzed. 25(OH) D concentrations were measured using liquid chromatography-tandem mass spectrometry. Results: Of 210,695 patients, serum 25(OH) D concentrations were measured for 3,276 (1.6%), 78% of whom were Hispanic, 69% female, 14% hospitalized, and 86% ambulatory. Median patient age was 54 years. Prevalence of 25(OH) D <10 ng/mL was 6.5% overall, 5.5% in Hispanics, 6.7% in Asians, 15.5% in African Americans, and 8.9% in whites. Prevalence was significantly higher in African Americans than in Hispanics (relative risk (RR): 2.79), males (RR: 2.07), hospitalized patients (RR: 4.96), and winter (RR: 1.34). Prevalence of 25(OH) D <20 ng/mL was 35% overall, 34% in Hispanics, 32% in Asians, 49% in African Americans, and 33% in whites, and was significantly higher in African Americans than Hispanics (RR: 1.45), males (RR: 1.32), hospitalized patients (RR: 2.02), and younger patients (RR: 1.21, age <= 30; 1.16, age 31-50) versus those age 51 to 70 years, and in winter (RR: 1.21). Conclusion: Our study estimated the prevalence of 25(OH) D deficiency and identified at-risk patient groups in Southern California; 25(OH) D deficiency should be suspected, diagnosed, and adequately treated to improve the health status in at-risk urban indigent patient populations.