Serum levels of C-terminal agrin fragment (CAF) are associated with sarcopenia in older hip fractured patients

Abstract

Background: Serum concentrations of the C-terminal fragment of agrin (CAF), a component of the neuromuscular junction (NMJ), are elevated in older community-dwellers with sarcopenia. Whether CAF may be used as a marker for muscle wasting in the presence of NMJ mechanical damage is presently unknown. The present study was undertaken to verify if serum CAF levels were associated with sarcopenia in older hip fractured patients.

Methods: Analyses were conducted in older adults hospitalized for traumatic hip fracture. The presence of sarcopenia was established according to the European Working Group on Sarcopenia in Older People criteria, with bioelectrical impedance analysis used for muscle mass estimation. Serum levels of CAF were determined using a commercial ELISA kit.

Results: Among 42 hip fractured patients (age 83.7±8.6 years, 76.2% women), sarcopenia was diagnosed in 7 individuals (16.7%). Serum CAF levels were significantly higher in sarcopenic relative to non-sarcopenic patients (172.2±47.5 pM vs. 93.1±44.0 pM; p<0.001). The association remained significant in both genders after adjustment for several potential confounders.

Conclusion: Elevated serum CAF concentrations are associated with sarcopenia in older adults with hip fracture. The determination of serum CAF levels could therefore serve to identify a subset of hip fractured patients at especially high risk for adverse health outcomes.

Keywords: Aging; Bioelectrical impedance analysis (BIA); Biomarker; Handgrip; Muscle atrophy; Muscle injury; Neuromuscular junction.