Two-year Follow-up of IgA Nephropathy Patients Who Developed Gross Hematuria Following COVID-19 Vaccination: A Case Series and Literature Review.

Abstract

Objective Recent reports have shown that patients with immunoglobulin A nephropathy (IgAN) develop gross hematuria after COVID-19 vaccination. However, the two-year prognosis remains uncertain. Methods We conducted a retrospective review of 301 patients with IgAN at our institution to identify those who developed gross hematuria after COVID-19 vaccination. We evaluated the patients' baseline characteristics, clinical courses, and changes in the renal function, proteinuria, and hematuria for two years post-vaccination. In addition, we conducted a systematic literature review of 16 case studies, with 28 cases and 5 cohort studies. Results Gross hematuria was observed in eight patients after vaccination. Their mean age was 42.9 years, and 87.5% were women. All patients relapsed or did not achieve clinical remission prior to vaccination. The median time to gross hematuria onset was 1.6 days, resolving within 3 days. The mean baseline estimated glomerular filtration rate (eGFR) was 69.4 mL/min/1.73 m², the urine protein-to-creatinine ratio (UPCR) was 0.23 g/gCr, and the median baseline hematuria was 10-19 red blood cells (RBCs)/high-power field (HPF). One month after vaccination, the eGFR decreased by 8.6 mL/min/1.73 m² (-12.3%), the UPCR increased by 0.64 g/gCr, and hematuria increased to 50-99 RBCs/HPF. By 6 months, the eGFR and UPCR had recovered, with median hematuria decreasing to 5-9 RBCs/HPF and stabilizing by 24 months. Conclusion We revealed the extended prognosis of gross hematuria in patients with IgAN following COVID-19 vaccination. With appropriate follow-up, temporary renal deterioration improved within six months and remained stable for two years. These findings support the safety of the COVID-19 vaccination in this vulnerable population.