Do specific plasma metabolites change in older patients with sepsis and sarcopenia?
Sepsis triggers a severe stress response, and when older patients also have sarcopenia (loss of muscle mass and strength), their metabolism may be affected in unique ways. A 2025 study directly examined this question by comparing plasma metabolites in older septic patients with and without sarcopenia. The researchers found clear differences: the sarcopenia group had 203 significantly changed metabolites, with most being downregulated, suggesting an overall 'inhibitory' metabolic state 3. These changes involved key pathways such as amino acid breakdown, fatty acid metabolism, and steroid hormone synthesis 3.
What the research says
A prospective observational study of 84 older patients with sepsis (35 with sarcopenia, 49 without) used advanced mass spectrometry to analyze fasting plasma samples 3. Out of 4,752 identified metabolites, 203 were significantly different between the two groups: 71 were increased and 132 were decreased in the sarcopenia group 3. The downregulated metabolites were mainly involved in the breakdown of branched-chain amino acids (valine, leucine, isoleucine), arachidonic acid metabolism, and steroid hormone synthesis 3. These findings indicate that sarcopenia in sepsis is linked to a distinct 'inhibitory' metabolic profile, which may reflect altered energy use and inflammation regulation 3.
Separate research in non-sepsis populations also highlights specific metabolites linked to sarcopenia. A large study of 1,013 individuals found that plasma sarcosine levels were notably lower in older adults with sarcopenia 9. In mice, sarcosine helped preserve muscle mass and promote muscle regeneration by activating anti-inflammatory immune cells 9. While this study did not involve sepsis, it suggests that sarcosine decline may be a general feature of sarcopenia that could be relevant in sepsis as well 9.
Other sources provide context on related metabolic factors. For example, a meta-analysis found that exercise interventions can reduce the inflammatory marker TNF-alpha in older adults with sarcopenia, though effects on IL-6 and CRP were not significant 4. Additionally, a narrative review linked ultra-processed food intake to low-grade inflammation and functional decline, which may worsen sarcopenia 7. These findings underscore that metabolism and inflammation are closely tied to muscle health in older adults.
What to ask your doctor
- Could my or my family member's plasma metabolite levels be tested to assess sarcopenia risk during sepsis?
- What do changes in amino acid or steroid hormone levels mean for recovery from sepsis?
- Are there any dietary or supplement strategies (like branched-chain amino acids or sarcosine) that might help support muscle health during sepsis recovery?
- How does inflammation affect muscle loss in sepsis, and are there treatments to reduce that effect?
- Should we monitor muscle mass and function regularly after sepsis to catch sarcopenia early?
This question is drawn from common patient questions about Geriatrics & Aging and answered using cited medical research. We do not provide individualized advice.