Gross hematuria can be an impact of severe acute respiratory syndrome coronavirus 2 vaccination on immunoglobulin A nephropathy: a case report

BACKGROUND: Immunoglobulin A nephropathy is typically accelerated by upper respiratory tract infections and can relapse following vaccination. There have been reports of patients who presented with immunoglobulin A nephropathy flares with or without gross hematuria following coronavirus disease 2019 vaccination. However, this relationship remains to be elucidated. CASE PRESENTATION: Herein, we present the case of a patient with newly diagnosed immunoglobulin A nephropathy who presented with gross hematuria following the second dose of coronavirus disease 2019 vaccine. A 21-year-old Japanese woman presented with fever and new-onset gross hematuria 1 day after receiving the second dose of the coronavirus disease 2019 vaccine (Pfizer). She had microhematuria without proteinuria for 2 years at the time of her medical check-up. Gross hematuria resolved 6 days after the second dose of the coronavirus disease 2019 vaccine; however, microhematuria (> 100 per high-power field) and mild proteinuria were observed. She was admitted to our hospital 4 weeks after the second vaccination because of persistent urinary abnormalities. She was well before the vaccination and did not have any pulmonary involvement on chest radiography or any symptoms suggestive of coronavirus disease 2019. Renal biopsy revealed an immunoglobulin A nephropathy. The Oxford MEST-C score was M0E0S0T0C0. Our patient’s urinary abnormalities implied exacerbation of immunoglobulin A nephropathy after coronavirus disease 2019 vaccination. CONCLUSIONS: In our case, gross hematuria served as a trigger for immunoglobulin A nephropathy diagnosis, suggesting that nephrologists should pay close attention to gross hematuria and urinalysis after coronavirus disease 2019 vaccination.