Proteinuria occurs commonly among HIV-infected and -uninfected injection drug users (IDUs) and is associated with increased mortality risk. Vitamin D deficiency, highly prevalent among IDUs and potentially modifiable, may contribute to proteinuria. To determine whether vitamin D is associated with proteinuria in this population, we conducted a cross-sectional study in the AIDS Linked to the IntraVenous Experience (ALIVE) Study.
25(OH)-vitamin D levels were measured in 268 HIV-infected and 614 HIV-uninfected participants. The association between vitamin D deficiency (<10 ng/mL) and urinary protein excretion was evaluated by linear regression. The odds of persistent proteinuria (urine protein-to-creatinine ratio >200 mg/g on two occasions) associated with vitamin D deficiency was examined using logistic regression.
One-third of participants were vitamin D-deficient. Vitamin D deficiency was independently associated with higher urinary protein excretion (P<0.05) among HIV-infected and diabetic IDUs (P-interaction<0.05 for all). Persistent proteinuria occurred in 18% of participants. Vitamin D deficiency was associated with >6-fold odds of persistent proteinuria among diabetic IDUs (odds ratio [OR]=6.29, 95% confidence interval [CI]: 1.54, 25.69) independent of sociodemographic characteristics, co-morbid conditions, body mass index, and impaired kidney function (estimated GFR <60 mL/min|1.73 m2); no association, however, was observed among non-diabetic IDUs (OR=1.06, 95% CI: 0.64, 1.76) (P-interaction<0.05).
Vitamin D deficiency was associated with higher urinary protein excretion among those with HIV infection and diabetes. Vitamin D deficiency was independently associated with persistent proteinuria among diabetic IDUs, although not in non-diabetic persons. Whether vitamin D repletion ameliorates proteinuria in these patients requires further study.