Bioavailable Vitamin D Levels in Children With First Episode Nephrotic Syndrome: A Longitudinal Study.

Area of Science:

• Pediatric Nephrology
• Endocrinology
• Nutritional Science

Background:

• First episode nephrotic syndrome (FENS) is a common kidney disorder in children.
• Vitamin D deficiency is prevalent in various chronic conditions, potentially impacting FENS.
• Assessing bioavailable vitamin D is crucial for understanding its role in FENS.

Purpose of the Study:

• To measure serum bioavailable vitamin D in children with FENS at diagnosis and after treatment.
• To compare vitamin D levels in FENS patients with healthy controls.
• To evaluate changes in vitamin D status following steroid therapy in FENS remission.

Main Methods:

• Included children aged 1 month to 12 years with FENS.
• Measured serum calcium, phosphorus, alkaline phosphatase, 25-hydroxy vitamin D [25(OH)D], parathormone, and vitamin D binding protein (VDBP).
• Estimated bioavailable and free 25(OH)D at diagnosis and after 4 weeks of steroid therapy; included healthy controls.

Main Results:

• Children with FENS showed lower mean 25(OH)D levels (11.3 ng/mL) compared to controls (16 ng/mL).
• Bioavailable vitamin D was significantly lower in FENS patients (0.58 ng/mL) versus controls (0.97 ng/mL), improving to 0.87 ng/mL in remission.
• Strong positive correlation found between free and bioavailable vitamin D (r=0.9); negative correlation between VDBP and bioavailable vitamin D (r=-0.69).

Conclusions:

• Children with FENS exhibit vitamin D deficiency.
• Reduced free and bioavailable vitamin D levels are characteristic of the proteinuric phase in FENS.
• Further research is needed to link bioavailable vitamin D and bone mineral density in pediatric nephrotic syndrome.