# Vitamin D Deficiency in Relapsing Idiopathic Nephrotic Syndrome in Children: Prevalence, Correlates, and Therapeutic Implications

## TL;DR

This study finds that most children with relapsing kidney disease have low vitamin D levels, which are linked to more severe symptoms and frequent relapses.

## Contribution

The study identifies a strong link between vitamin D deficiency and disease severity in relapsing pediatric nephrotic syndrome.

## Key findings

- 84% of children with relapsing nephrotic syndrome were vitamin D deficient during relapse.
- Low vitamin D levels correlated strongly with higher proteinuria and more frequent relapses.
- Only 7% of patients achieved sufficient vitamin D levels after six months.

## Abstract

Idiopathic nephrotic syndrome (NS) is a common cause of glomerulonephritis in children, often complicated by relapses and steroid dependence or resistance. Emerging evidence underscores the interplay between vitamin D metabolism and NS pathophysiology, particularly during relapse episodes.

To investigate the prevalence of vitamin D deficiency in pediatric patients aged 2–12 years with relapsing idiopathic NS and to evaluate associations with proteinuria severity, relapse frequency, and steroid exposure.

This cross‐sectional study included 100 children diagnosed with idiopathic NS and at least one documented relapse. We enrolled all NS patients with completed follow‐up for 1 year. Serum 25‐hydroxyvitamin D (25[OH]D) levels were measured during relapse and six months later. Clinical and biochemical data, including proteinuria, albumin, creatinine, and corticosteroid usage, were analyzed.

At relapse, 84% of patients were vitamin D deficient, with only 7% reaching sufficiency after 6 months. A significant inverse correlation was observed between 25(OH)D levels and both proteinuria (r = −0.62, p < 0.001) and relapse frequency (r = −0.48, p < 0.01). Corticosteroid dosage was not significantly associated with vitamin D recovery.

Vitamin D deficiency is highly prevalent among children with relapsing idiopathic NS and correlates with greater disease activity. Routine monitoring and timely supplementation of vitamin D may be essential components in managing NS flares and preventing long‐term complications.