Vitamin D Deficiency More Common in Lupus Nephritis Than Lupus Without Kidney Disease

Alicia Yupe, MD

Credit: LinkedIn

Hypovitaminosis D is more prevalent in patients with lupus nephritis than in patients with systemic lupus erythematosus without kidney disease, according to findings from a recent study.¹

The research was presented at the American College of Rheumatology (ACR) Convergence 2024, in Washington, DC, by Alicia Yupe, MD, faculty of medical sciences at the University of San Carlos in Guatemala, and additionally links greater proteinuria in lupus nephritis to more severe vitamin D deficiency in these patients.¹

Although the prevalence of vitamin D deficiency is known to be increased in patients with systemic lupus erythematosus relative to the healthy population, recent studies have observed a greater prevalence of hypovitaminosis D in patients with associated kidney disease. Notably, this deficiency has been proposed as a risk factor for a higher incidence and activity of autoimmune diseases, a topic discussed by Margherita Cantorna, PhD, a distinguished professor of molecular immunology at Penn State University, during a session at ACR.^1,2

“Cells of the immune system require vitamin D to control the amount of inflammation. Without vitamin D, inflammation is increased and contributes to autoimmunity,” Cantorna said in a press release, calling attention to a current lack of consensus about optimal vitamin D levels and subsequent uncertainties about vitamin D requirements in different patient populations to improve outcomes.²

To determine the prevalence of hypovitaminosis D and its correlation with clinical and renal activity and histopathological findings of renal biopsy, Yupe and colleagues conducted an analytical cross-sectional study in patients with systemic lupus erythematosus according to the 2019 EULAR/ACR criteria and lupus nephritis by renal biopsy according to ISN/RPS of 2003.¹

Disease activity was measured by SLEDAI 2K, with high activity defined as > 4 points. Renal activity was measured through creatinine, BUN, urinary sediment, albuminuria, urinary creatinine protein ratio, 24-hour urine protein count, GFR, renal biopsy report, activity index, and chronicity. Serum vitamin D levels were measured by ELISA (Human soluble 25-OH Vitamin D ELISA Kit Eagle Bioscences), with hypovitaminosis D defined as < 30 ng/mL.¹

In total, 24 patients with systemic lupus erythematosus were included in the study, 16.7% of whom were male with a mean age of 30.8 (SD, 9.2) years. Investigators divided patients into 2 groups: those with lupus nephritis (n = 12) and those without renal involvement (n = 12).¹

Among the cohort, 58% of patients had hypovitaminosis D. Investigators noted there was a higher prevalence of vitamin D deficiency in patients with lupus nephritis than in those with systemic lupus erythematosus without kidney disease (75% vs 42%).¹

Further analysis revealed vitamin D levels had a moderate negative correlation with 24-hour urine protein count (r =-0.594; P = .042) in patients with lupus nephritis. Additionally, in the renal biopsy lesions, 100% of patients had rupture of the glomerular basement membrane and interstitial inflammation, followed by endocapillary hypercellularity in 91.7%, although neither was specifically correlated to hypovitaminosis D.¹

“Hypovitaminosis D has a higher prevalence in patients with lupus nephritis compared to patients with systemic lupus erythematosus without kidney disease,” investigators concluded.¹ “In patients with lupus nephritis, the greater the proteinuria, the greater the vitamin D deficiency.”

References

1. ^{Yupe A, Gonzalez EP, Salatino E, et al. Hypovitaminosis D in Lupus Nephitis [abstract]. Arthritis Rheumatol. 2024. https://acrabstracts.org/abstract/hypovitaminosis-d-in-lupus-nephitis/.}
2. ^{American College of Rheumatology. Vitamin D Research Goes Beyond Bones to Show Autoimmune & Inflammation Connection. November 14, 2024. Accessed November 25, 2024. https://assets.contentstack.io/v3/assets/bltee37abb6b278ab2c/bltd292facfe74bf4cd/annual-meeting-press-release-catorna-vitamin-d.pdf}