Kidney Week

Abstract: TH-PO0575

Combined Cystatin C- and Creatinine-Based Kidney Function Assessment in Patients with High BMI and Low Lean BMI: An Observational Study in Japan

Session Information

• CKD: From Global Burden to Precision Care - Epidemiology, Demographics, Geographies, and Risk Factors
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 2201 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

• Hiramatsu, Miya, Nagoya Daigaku Daigakuin Igakukei Kenkyuka Igakubu, Nagoya, Aichi Prefecture, Japan

Miya Hiramatsu, MD

• Kato, Sawako, Nagoya Daigaku Daigakuin Igakukei Kenkyuka Igakubu, Nagoya, Aichi Prefecture, Japan

Sawako Kato, MD, PhD

• Sugishita, Akitaka, Nagoya Daigaku Igakubu Fuzoku Byoin, Nagoya, Aichi Prefecture, Japan

Akitaka Sugishita

• Yamada, Takumi, Nagoya Daigaku Daigakuin Igakukei Kenkyuka Igakubu, Nagoya, Aichi Prefecture, Japan

Takumi Yamada, MD

• Asano, Yuko, Nagoya Daigaku Daigakuin Igakukei Kenkyuka Igakubu, Nagoya, Aichi Prefecture, Japan

Yuko Asano, MD

• Imaizumi, Takahiro, Nagoya Daigaku Daigakuin Igakukei Kenkyuka Igakubu, Nagoya, Aichi Prefecture, Japan

Takahiro Imaizumi, MD, PhD

• Maruyama, Shoichi, Nagoya Daigaku Daigakuin Igakukei Kenkyuka Igakubu, Nagoya, Aichi Prefecture, Japan

Shoichi Maruyama, MD, PhD

• Mizuno, Masaaki, Nagoya Daigaku Igakubu Fuzoku Byoin, Nagoya, Aichi Prefecture, Japan

Masaaki Mizuno, MD, PhD

Background

Cystatin C- and creatinine-based eGFR are widely used in clinical practice, but creatinine is influenced by muscle mass and cystatin C by fat mass and inflammation, so either marker alone may misrepresent renal function. We therefore used Body Mass Index (BMI)–Lean Body Mass Index (LBMI) combinations to identify populations in which the discrepancy between the two markers (eGFR_diff) is more likely to occur.

Methods

This cross-sectional retrospective study used 2018 health checkup data from Kasugai City, Japan. Participants with eGFR_cr < 15 mL/min/1.73 m² or a history of Parkinson's disease were excluded, and a complete-case analysis was performed on those with both cystatin C and creatinine measurements. eGFR was calculated using the Japanese Society of Nephrology formula, and eGFR_diff was defined as eGFR_cys − eGFR_cr. Correlation and multivariate regression analyses were performed between creatinine and cystatin C.

Results

This study included 9,321 participants (mean age 63.7 ± 13.3 years; 4,621 [49.6%] male). Mean eGFR_cr was 70.3 ± 14.8 mL/min/1.73 m², eGFR_cys 87.3 ± 21.6 mL/min/1.73 m², and BMI 22.5 ± 3.2 kg/m². eGFR_cr and eGFR_cys were strongly correlated (ρ = 0.71; Figure 1). Participants were stratified by sex into four groups based on median BMI and LBMI: Group 1 (high BMI, low LBMI), Group 2 (low BMI, low LBMI), Group 3 (low BMI, high LBMI; reference), and Group 4 (high BMI, high LBMI). In multivariate regression, Group 1 showed the largest negative deviation in eGFR_diff vs. Group 3, followed by Group 4 and Group 2 in both sexes (women: β = −8.28, −7.70, −4.91; men: β = −5.88, −5.04, −3.44; all p < 0.001).

Conclusion

The negative deviation in eGFR_diff was greater in individuals with normal-to-high BMI but low LBMI than in those with both low BMI and low LBMI. In such populations, renal function should be carefully evaluated using cystatin C in addition to creatinine.