Kidney Week

Abstract: FR-PO0934

Pathological Progression During Isolated Hematuria in Childhood IgAN

Session Information

• Pediatric Nephrology: Genetic Diseases, Development, Neonatal Nephrology, Glomerular Diseases, and More
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

• 1800 Pediatric Nephrology

Authors

• Shima, Yuko, Wakayama Kenritsu Ika Daigaku, Wakayama, Wakayama Prefecture, Japan

Yuko Shima, MD, PhD

• Mukaiyama, Hironobu, Wakayama Kenritsu Ika Daigaku, Wakayama, Wakayama Prefecture, Japan

Hironobu Mukaiyama, MD

• Tanaka, Yu, Wakayama Kenritsu Ika Daigaku, Wakayama, Wakayama Prefecture, Japan

Yu Tanaka

• Shimabukuro, Wataru, Ryukyu Daigaku Igakubu Daigakuin Igaku Kenkyuka, Ginowan, Okinawa Prefecture, Japan

Wataru Shimabukuro, MD, PhD

• Kaito, Hiroshi, Hyogo Kenritsu Kodomo Byoin, Kobe, Hyogo Prefecture, Japan

Hiroshi Kaito, MD, PhD

• Tanaka, Ryojiro, Hyogo Kenritsu Kodomo Byoin, Kobe, Hyogo Prefecture, Japan

Ryojiro Tanaka, MD

• Nozu, Kandai, Kobe Daigaku Daigakuin Igakukei Kenkyuka Igakubu, Kobe, Hyogo Prefecture, Japan

Kandai Nozu, MD, PhD

• Iijima, Kazumoto, Kobe Daigaku Daigakuin Igakukei Kenkyuka Igakubu, Kobe, Hyogo Prefecture, Japan

Kazumoto Iijima, MD, PhD

• Tokuhara, Daisuke, Wakayama Kenritsu Ika Daigaku, Wakayama, Wakayama Prefecture, Japan

Daisuke Tokuhara, MD, PhD

• Yoshikawa, Norishige, Takatsuki Byoin, Takatsuki, Osaka Prefecture, Japan

Norishige Yoshikawa, MD, PhD

• Nakanishi, Koichi, Ryukyu Daigaku Igakubu Daigakuin Igaku Kenkyuka, Ginowan, Okinawa Prefecture, Japan

Koichi Nakanishi, MD, PhD

Background

Proteinuria remission is a key predictor of kidney outcome in childhood IgA nephropathy (cIgAN). In Japan, kidney biopsy is generally performed after persistent proteinuria develops, whereas patients with isolated hematuria are usually monitored without biopsy. This strategy assumes limited clinicopathological progression before overt proteinuria; however, supporting evidence remains limited.

Methods

We retrospectively analyzed 327 patients with biopsy-proven cIgAN diagnosed at Kobe University and Wakayama Medical University between 1990 and 2022 and followed for at least 2 years. Patients were stratified according to the interval from onset to kidney biopsy into three groups: ≤1 year, 1–3 years, and ≥3 years. In both institutions, persistent proteinuria generally prompted biopsy, with earlier biopsy in patients with heavy proteinuria or severe clinical findings. Clinical and pathological data were compared among groups. Proteinuria remission was evaluated using the Kaplan–Meier method.

Results

Patients biopsied within 1 year of onset commonly had persistent proteinuria from the early disease phase and therefore underwent earlier biopsy. In contrast, many patients biopsied ≥3 years after onset had prolonged isolated hematuria or fluctuating mild urinary abnormalities before biopsy. Clinical and histopathological analyses demonstrated limited disease progression, although patients with longer pre-biopsy duration exhibited a modestly greater burden of chronic lesions. However, patients biopsied ≥3 years after onset showed significantly lower proteinuria remission rates than those biopsied within ≤1 year (p=0.007) or 1–3 years (p=0.04), whereas no significant difference was observed between the 1-year and 1–3-year groups (p=0.49). Kidney survival did not differ significantly among groups.

Conclusion

Although major clinicopathological progression before overt proteinuria appeared limited in most patients with cIgAN, delayed biopsy beyond 3 years from urinary abnormality onset was associated with poorer proteinuria remission. These findings suggest that prolonged observation before biopsy may be associated with reduced treatment responsiveness and warrant careful monitoring.