Gross Hematuria After COVID-19 Vaccination Tied to Temporary Kidney Function Decline in IgAN Patients: Study
Japan: New research indicates that patients with IgA nephropathy (IgAN) who develop gross hematuria (GH) after COVID-19 vaccination may experience a short-term decline in kidney function, though differences lessen over time. Further, female patients and those with IgAN or IgA vasculitis appear more susceptible to gross hematuria (GH) following vaccination.
A recent study published in Scientific Reports by Dr. Shinya Yokote and colleagues from the Division of Nephrology at Kawaguchi Municipal Medical Center, Japan, examined how the onset of GH after COVID-19 mRNA vaccination affects kidney function in patients with biopsy-confirmed IgAN. While there have been increasing reports of GH after vaccination in this patient group, the long-term clinical implications have remained uncertain.
The researchers retrospectively analyzed data from 441 Japanese outpatients diagnosed with IgAN, with a median age of 51 years, of whom 56% were female. The participants were divided into three groups: unvaccinated individuals (25), vaccinated individuals without GH (391), and vaccinated individuals who experienced GH (25). Kidney function was tracked over approximately two years, using estimated glomerular filtration rate (eGFR) as the primary indicator.
The key findings of the study were as follows:
- At the one-year follow-up, the annual change in eGFR was −1.16 mL/min/1.73 m² in the unvaccinated group, −1.03 in the vaccinated group without gross hematuria (GH), and −2.50 in the vaccinated group with GH.
- Patients who developed GH showed a significantly greater decline in kidney function compared to those without GH.
- GH was independently associated with an increased risk of eGFR decline at the one-year mark (odds ratio, 2.97).
- At the two-year follow-up, the annual eGFR change was −0.45 in the unvaccinated group, −1.93 in the vaccinated non-GH group, and −1.72 in the GH group.
- No significant long-term differences in kidney function were observed among the three groups.
- The findings suggest that while GH after vaccination is associated with an early decline in kidney function, this decline tends to stabilize over time.
According to the authors, this is the first study to specifically explore the relationship between post-vaccination GH and kidney function trajectory in IgAN patients using longitudinal eGFR data. The findings provide valuable real-world evidence regarding the short-term effects of GH following COVID-19 vaccination.
The researchers cautioned that the study’s retrospective nature and the relatively small number of GH cases limit the strength of the conclusions. Since the classification of GH relied on self-reported data collected during routine visits, recall bias and underreporting cannot be ruled out. Additionally, kidney function was evaluated only at three time points—baseline, one year, and two years—potentially missing transient changes in kidney function.
In conclusion, the study suggests that GH levels after COVID-19 mRNA vaccination may be associated with a temporary decline in kidney function in patients with IgA nephropathy, without lasting long-term effects. The authors emphasized that these results are associative and should be interpreted cautiously. They called for larger, multicenter prospective studies to validate the findings and clarify whether the observed relationship is causal.
Reference:
Yokote, S., Okabe, M., Shimizu, A., Haruhara, K., Fukunaga, S., Sasaki, T., Fujimoto, T., Ueda, H., Tsuboi, N., & Yokoo, T. (2025). Gross hematuria after COVID-19 mRNA vaccination and kidney function trajectory in IgA nephropathy. Scientific Reports, 15(1), 1-8. https://doi.org/10.1038/s41598-025-19068-6
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