Scientists from The University of Manchester and Northern Care Alliance NHS Foundation Trust have discovered that the combination of two biomarkers can reliably identify sarcopenia, a serious condition of the muscle linked to higher mortality in chronic Kidney Disease (CKD).
The test, say the researchers, could identify individuals at risk of the condition which is typified by loss of muscle mass and strength as well as an overall poorer quality of life.
The study, published in the journal PLOS Med today (12/02/26) and funded by Kidney Research UK and the Donal O'Donoghue Renal Research Centre", is the first large scale study to demonstrate the viability of the test - called creatinine muscle index (CMI) in CKD.
The researchers created CMI by combining two routine blood tests, creatinine and cystatin C.
While both tests used to assess kidney function, creatinine levels are influenced by how much muscle a person has, whereas cystatin C is not.
By comparing the two, the researchers were able to use this difference to estimate a person's risk of muscle loss and therefore sarcopenia.
Because kidney disease affects how creatinine is processed, scientists did not know if CMI would work well in people with CKD.
However, the study shows that CMI remains independently associated with both muscle function and survival.
The test could enable earlier detection of sarcopenia, allowing patients to start proven interventions-such as resistance exercise training and protein supplementation-sooner, and potentially lower their risk of death.
The study included 2,930 adults with non-dialysis CKD from 16 kidney centres across the UK between July 2017 and September 2019.
Participants had their CMI and muscle function in terms of grip strength and walking speed measured and were followed up for a median of 50 months.
In both men and women, lower CMI - indicating lower muscle mass- was linked to weaker hand grip strength, slower walking speed and a higher risk of sarcopenia.
Higher CMI was also linked to a lower risk of death. The average CMI in men and women was 864 mg/day and 704 mg/day. For every 100 mg/day per 1.73 m² increase in CMI The risk of death fell by 15% in men and 23% in women.
And CMI outperformed other cystatin C-creatinine-based measures in predicting mortality and sarcopenia.
Lead author Dr Thomas McDonnell is both a researcher at The University of Manchester and a kidney doctor at Salford Royal Hospital, part of Northern Care Alliance NHS Foundation Trust.
He said: "Sarcopenia, in people with chronic kidney disease is associated with increased mortality, poorer self-reported health-related quality of life, and reduced functional status.
"Simple identification of sarcopenia should be routinely undertaken in people with CKD, not only because of its association with adverse outcomes but also due to the availability of interventions that can reverse it in people with CKD.
"That could have significant implications on patient wellbeing.
"Our findings also highlight CMI's superiority over alternative tests, and provides exciting evidence for its potential as a blood-based biomarker of sarcopenia and mortality risk."
NURTuRE-CKD is a prospective, multicentre cohort study of people with non-dialysis CKD in the U.K
