Objectives:
Henoch-Schönlein purpura (HSP), also known as IgA vasculitis (IgAV), is the most prevalent systemic vasculitis. Renal involvement occurs in approximately one third of children with IgAV, while biopsy-proven nephritis could be diagnosed in only 6% of patients with prolonged proteinuria or nephritic syndrome. The renal resistive index (RRI) provides insights into intrarenal arte­rial resistance. The aim of this study was to assess the potential utility of RRI measurements in patients with IgA vasculitis (IgAV).

Material and methods:
This cross-sectional study included 27 children diagnosed with HSP/IgAV between January 2021 and January 2023. Additionally, 27 healthy controls were included to the study. Age, sex, symptoms recorded and initial laboratory test results, including renal function tests, serum albumin levels, complete blood count, erythrocyte sedimentation rate, C-reactive protein, renal function tests, spot urine protein/creatinine and albumin/creatinine ratio were obtained at study enrollment. The RRI measurements were obtained from intrarenal arteries using color Doppler ultrasonography.

Results:
Among the 27 IgAV patients (13 male, 14 female), 3 (11.1%) exhibited renal involvement, with renal biopsy performed in only one patient, revealing class IIIa nephritis. The RRI values were not significantly different between the IgAV and control groups. Additionally, RRI was 0.61 ±0.05 and 0.56 ±0.06 in patients with and without antecedent infection, respectively (p = 0.04). Furthermore, RRI was not significantly different among patients grouped based on the presence of arthritis, severe gastrointestinal symptoms, or renal involvement.

Conclusions:
Our findings indicate that RRI remains unaffected in patients with IgAV, reflecting the relatively benign nature of the disease, particularly in children. Further investigations, involving a larger cohort of patients with nephritis, are warranted to elucidate the utility of RRI in assessing renal involvement in IgAV.