New Blood Test Reliably Detects Muscle Wasting in Kidney Disease Patients
Scientists from The University of Manchester and Northern Care Alliance NHS Foundation Trust have identified a new method using two biomarkers to reliably detect sarcopenia, a muscle-wasting condition linked to increased mortality in chronic kidney disease (CKD) patients. This breakthrough offers a promising tool for early diagnosis and intervention.
Introducing Creatinine Muscle Index (CMI)
The novel test, named creatinine muscle index (CMI), combines two routine blood tests: creatinine and cystatin C. Creatinine levels are primarily influenced by muscle mass, while cystatin C levels are not. This crucial difference allows researchers to estimate an individual's risk of muscle loss and sarcopenia by comparing these two markers.
Validating CMI in CKD Patients
Previous concerns existed regarding CMI's efficacy in CKD patients, mainly due to how kidney disease affects creatinine processing. However, a large-scale study, published in PLOS Med and funded by Kidney Research UK and the Donal O'Donoghue Renal Research Centre, has now definitively demonstrated CMI's independent association with muscle function and survival in individuals with CKD.
"CMI's independent association with muscle function and survival in CKD has been definitively demonstrated."
Key Study Findings
The study involved 2,930 adults with non-dialysis CKD from 16 UK kidney centers. Participants' CMI and muscle function (measured by grip strength and walking speed) were assessed, with follow-up conducted for a median of 50 months.
Results showed a clear correlation:
- Lower CMI, indicating reduced muscle mass, correlated with weaker hand grip strength, slower walking speed, and a higher risk of sarcopenia.
- Conversely, higher CMI was significantly linked to a lower risk of death.
- Specifically, for every 100 mg/day per 1.73 m² increase in CMI, the risk of death decreased by 15% in men and 23% in women.
Implications for Patient Care
CMI was found to outperform other cystatin C-creatinine-based measurements in predicting both mortality and sarcopenia. This early detection capability is crucial, as it could enable patients to access proven interventions, such as resistance exercise and protein supplementation, sooner. Such timely interventions have the potential to significantly reduce their risk of death and improve quality of life.
Dr. Thomas McDonnell, lead author of the study and a kidney doctor at Salford Royal Hospital, underscored the importance of these findings.
"Sarcopenia in CKD is associated with increased mortality, poorer quality of life, and reduced functional status. Given its strong link with adverse outcomes and the availability of effective reversal interventions, routine sarcopenia identification in CKD patients is something we should be doing."