Kidney Week

Abstract: TH-PO1008

Single Nephron Parameters in Patients with IgA Nephropathy

Session Information

• Glomerular Diseases: Minimal Change Disease, FSGS, IgAN
  November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

• Marumoto, Hirokazu, The Jikei University School of Medicine, Tokyo, Japan

Hirokazu Marumoto,

• Tsuboi, Nobuo, The Jikei University School of Medicine, Tokyo, Japan

Nobuo Tsuboi,

• Sasaki, Takaya, The Jikei University School of Medicine, Tokyo, Japan

Takaya Sasaki,

• Okabayashi, Yusuke, The Jikei University School of Medicine, Tokyo, Japan

Yusuke Okabayashi,

• Haruhara, Kotaro, The Jikei University School of Medicine, Tokyo, Japan

Kotaro Haruhara,

• Kanzaki, Go, The Jikei University School of Medicine, Tokyo, Japan

Go Kanzaki,

• Koike, Kentaro, The Jikei University School of Medicine, Tokyo, Japan

Kentaro Koike,

• Kawamura, Tetsuya, The Jikei University School of Medicine, Tokyo, Japan

Tetsuya Kawamura,

• Yokoo, Takashi, The Jikei University School of Medicine, Tokyo, Japan

Takashi Yokoo,

Background

The progression of IgA nephropathy (IgAN) may be characterized by progressive loss of functional nephrons and subsequent alterations in single nephron function in remnant nephrons. In this study, we estimated total nephron number and examined the related single nephron parameters in patients with IgAN at different renal function stages of the disease.

Methods

The total nephron number was calculated using a simplified method based on the combined use of unenhanced computed tomography and stereology-based estimation of non-sclerotic glomerular density on renal biopsy (Sasaki T et al. 2018, ASN). Single-nephron glomerular filtration rate (SNGFR) and single-nephron urinary protein excretion (SNUPE) were calculated by dividing the estimated glomerular filtration rate (eGFR) and urinary protein excretion by total nephron number, respectively. The glomerular volume (GV) was estimated from the measured mean glomerular area.

Results

A total of 107 Japanese IgAN patients (age 43, male 54%, eGFR 61.5 ± 24.2 ml/min/1.73m², urinary protein excretion 1.4 ± 1.6 g/day) were included. The total nephron number ranged from 78,000 to 1,989,000 per kidney (602,000 ± 378,000 on average per kidney). SNGFR showed a positive correlation with the GV (r = -0.37, p < 0.001). Advanced renal impairment of CKD stage 3b or more was characterized by increased SNGFR and markedly elevated SNUPE levels (Figure).

Conclusion

These results suggest a close association between loss of functional nephrons and changes in single nephron parameters in remnant nephrons, in parallel with progression of IgAN.