Serum Gelsolin Combined with Albumin Might Be a Promising Marker for the Intensive Care Unit-Acquired Weakness—A Pilot Study

<b>Background/Objectives</b>: Intensive care unit-acquired weakness (ICUAW) is a frequent complication characterized by symmetrical and proximal limb muscle weakness. Its diagnosis is primarily based on clinical symptoms; however, ICUAW assessment can often be uncertain. Blood biomarkers have not yet been widely investigated for this purpose. Serum gelsolin (GSN) is synthesized by skeletal muscle cells. It plays a crucial role in binding extracellular actin filaments and pro-inflammatory cytokines. In sepsis-associated ICUAW, GSN levels might massively decrease due to their buffering activity and muscle wasting. We elucidated the predictive capacity of GSN regarding ICUAW and its additional diagnostic/prognostic potential in sepsis compared to classical parameters. <b>Methods</b>: We recruited septic and non-septic ICU patients for our follow-up study. Patients were retrospectively categorized into ICUAW positive (<i>n</i> = 26) and negative (<i>n</i> = 47) groups based on their clinical characteristics. Sera were collected on the 1st, 2nd and 3rd days of ICU stay. Ambulatory patients (<i>n</i> = 34) served as controls. GSN levels were measured by our previously developed automated immunoturbidimetric assay. Clinical and laboratory parameters were collected from our hospital information system. <b>Results</b>: Admission GSN levels were significantly reduced in ICU patients compared to controls (median: 11.60 vs. 75.99 mg/L). ICUAW positive patients had significantly lower admission GSN levels than ICUAW negative patients (median: 8.10 vs. 14.30 mg/L), and a similar tendency was observed during follow-up. GSN showed predictive capacity regarding ICUAW (ROC AUC: 0.711, <i>p</i> < 0.01), especially when combined with albumin (ROC AUC: 0.750, <i>p</i> < 0.01). The combination of admission GSN, albumin, and procalcitonin demonstrated significant diagnostic performance (ROC AUC: 0.803) regarding the requirement for invasive ventilation, and GSN had prognostic value for 28-day mortality as well. <b>Conclusions</b>: GSN might serve as an intriguing marker in the prediction of ICUAW, especially when combined with albumin. The parallel decline of GSN and albumin could reflect the combined effects of systemic inflammation and muscle wasting seen in ICUAW.