Clinical and laboratory parameters associated with renal involvement in childhood IgA vasculitis: a prospective cohort study

Immunoglobulin A vasculitis (IgAV) is the most common small-vessel vasculitis in children and is a multisystemic disease affecting the skin, joints, gastrointestinal tract, and kidneys. Nephritis develops in 20–55% of children diagnosed with IgAV. This study aimed to evaluate the associations of admission neutrophil-to-lymphocyte ratio (NLR), serum osmolarity, homocysteine, vitamin B12, and antiphospholipid antibodies with renal involvement in children with IgAV. Forty children with IgAV were prospectively enrolled and followed for at least six months. The laboratory values analyzed were the first values obtained at the initial hospital presentation. Renal involvement was present at admission in eight patients and developed during follow-up in three patients; therefore, the admission measurements were concurrent with renal involvement in the former group and preceded renal involvement in the latter group. A total of 40 children with IgAV were included, of whom 23 (57.5%) were female and 17 (42.5%) were male, with a female-to-male ratio of 1.35. The mean age at diagnosis was 107.7 ± 40.3 months (9.0 ± 3.4 years). Renal involvement was identified in 11 patients (27.5%): eight at presentation and three during follow-up. NLR, serum urea, and serum osmolarity were significantly higher, whereas vitamin B12 levels were significantly lower, in patients with renal involvement ( p < 0.05). Serum potassium and homocysteine levels did not differ significantly between groups ( p > 0.05). Antiphospholipid antibody positivity was not associated with renal involvement. Admission NLR, serum osmolarity, and vitamin B12 levels were associated with renal involvement in this small prospective cohort. Because renal involvement was already present in most affected patients at the time of measurement, these findings should be interpreted as concurrent associations rather than validated predictors. Routine urinalysis remain essential, and these exploratory biomarkers require confirmation in larger prospective cohorts.