Stability of serum cytokeratin 18-M30 under different storage conditions for drug-induced liver injury assessment

Background: CK18-M30 is an emerging biomarker to be used in patients who have liver damage from drugs or other causes and is now commonly used as a marker of liver apoptosis in patients with drug-induced liver damage. Objectives: To investigate the effects of different storage conditions on the stability of human cytokeratin 18-M30 (CK18-M30) in serum, this study aims to provide data-driven evidence on sample stability for deferred laboratory testing of clinical specimens that cannot be analysed immediately. Methods: A total of 22 serum samples from individuals undergoing routine physical examination were collected and had different concentration levels of CK18-M30 in the Fourth Affiliated Hospital, Zhejiang University School. Baseline value from the immediate test. The remaining samples were distributed into five groups. Results: Aliquots stored at -20°C in cryotubes for 3 days and 2-8°C separation gel tube samples for 3 days had >80% concordance with the baseline and were not different (P > 0.05). Conversely, 2-8°C cryotube aliquots stored for 3 or 7 days, as well as 2-8°C separation gel tubes stored for 7 days, had concordance rates below 80%, significantly discrepant from the baseline (P < 0.01). Conclusions: CK18-M30 is relatively stable at -20°C. Between 2 and 8°C, the separation gel tubes were more stable than the aliquot tubes for up to three days. Aliquot tubes stored at 2-8oC were suboptimal, as the CK18-M30 became unstable after 3 days. The demonstrated stability characteristics of serum CK18-M30 are crucial for ensuring trustworthy biomarker-based safety evaluation when immediate analysis is not possible, given its expanding use as a safety and pharmacodynamic biomarker in pharmaceutical research, especially for tracking drug-induced liver injury in clinical trials and pharmacovigilance programs.