Serum biomarkers that predict lean mass loss over bed rest in older adults: An exploratory study

•Lean mass loss due to extended bed rest/hospitalization leads to long-term functional decline in older adults.•Blood biomarkers predictors of lean mass loss could increase awareness of lean mass loss that occurs during hospitalization.•Two pilot biomarker panels could predict lean mass loss over extended bed rest in older adults.•Panels included TIMP1 and Tenascin C, and Matrix metalloprotease-3 and Apolipoprotein A2. Lean mass (LM) loss during extended bed rest contributes to long term functional decline in older adults. Identifying blood biomarkers that predict a hospitalized individual’s risk of losing LM could allow for timely intervention. LM from 19 healthy subjects (age 60–76 y, 4 males, 15 females), who were confined to 10 days of complete bed rest, was measured pre- and post-bed rest. One hundred eighty-seven biomarkers from pre-bed rest fasted serum samples were obtained from all evaluable subjects (n = 18), analyzed using multiplexed immunoassay array and pooled. Decision tree analysis was used to identify pre-bed rest markers that predict LM loss over bed rest. Sixty-three markers were excluded due to being below assay detection limits. One pair of markers, Tissue inhibitor of metalloprotease-1 (TIMP1) and tenascin C (TNC), were found to correlate with percent change in total LM over bed rest: [R2 = 0.71, all subjects; R2 = 0.76, females]. Subjects with pre-bed rest TIMP1 ≥ 141 ng/ml had the highest loss of total LM over bed rest, whereas subjects with pre-bed rest TIMP1