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Abstract: TH-PO1035

The Impact of Muscle Mass on eGFR Accuracy with Creatinine and Cystatin C

Session Information

Category: CKD (Non-Dialysis)

  • 2302 CKD (Non-Dialysis): Clinical, Outcomes, and Trials


  • Gama, Rouvick, King's College London, London, United Kingdom
  • Dalrymple, Kathryn, King's College London, London, United Kingdom
  • Mangahis, Emmanuel, King's College London, London, United Kingdom
  • Bramham, Kate, King's College London, London, United Kingdom
  • Greenwood, Sharlene A., King's College London, London, United Kingdom

The use of creatinine (Cr) for estimating glomerular filtration rate (eGFR) is limited by non-GFR factors such as muscle mass, diet and drugs. Calculating lean tissue mass (LTM), a surrogate for muscle mass, or cystatin-c (Cys-c) – an alternative filtration marker unaffected by muscle mass or diet - may improve GFR estimation. We explored the relationship between LTM and eGFR accuracy using Cr and/or Cys-c, compared to measured GFR (mGFR) at multiple timepoints.


Participants with CKD were recruited. Demographics (age, sex, ethnicity) and 0, 6- and 12-month weight (kg), LTM (kg), mGFR, Cr and Cys-c were recorded. eGFR was calculated using the Modification of Diet for Renal Disease (MDRD), European Kidney Function Consortium (EKFC), CKD Epidemiology Collaboration (CKD-EPI) 2009, 2012 and 2021 equations for Cr, Cys-c and combined Cr-Cys-c. The relationship between LTM, mGFR and eGFR equations were assessed using beta coefficient. Association at baseline and over 12 months with LTM was assessed using regression analysis and multilevel mixed-effects linear regression respectively.


Of 41 participants, 28 (68.3%) were male and mean age was 53.2 ± 14.1 yrs. Baseline median (IQR) weight, LTM and mGFR were 85.5kg (71.2, 104.4), 44.3kg (36.5, 53.6) and 35 mL/min/1.73m2 (23.0, 46.0) respectively.

Baseline LTM (kg) was associated with higher values of mGFR-eGFR beta-coefficients for all Cr based equations (p<0.05). LTM as percentage of weight was weakly associated with CKD-EPI 2021 Cr equation (0.66; 95% CI 0.01-1.31;p<0.05). Cys-c eGFR equations compared with mGFR showed no significant associations with LTM. At 12 months, there was also a significant relationship between mGFR-eGFR Cr-based beta-coefficients (figure 1).


LTM was associated with Cr-based eGFR’s relationship with mGFR. There was no significant association involving Cys-c based equations, providing further evidence of independence of muscle mass, making its use more appealing in specific cohorts (e.g. liver cirrhosis, malignancy). Analysis of a larger cohort may allow a factor for LTM to further improve eGFR equation accuracy.