A systematic review on the definition of rhabdomyolysis.

BACKGROUND: Rhabdomyolysis (RML) is an interdisciplinary condition due to muscle cell injury followed by the release of cell components into circulation. Etiology of RML has a broad range; a serious complication is acute kidney injury (AKI). Despite its high relevance, there is no established formal definition for RML. OBJECTIVES: A systematic review, focusing on RML definition, providing a recommendation for clinicians. METHOD: Systematic literature research in PubMed and Embase (1968-07/2018). RESULTS: The database research presented 8136 articles in PubMed and 2151 in Embase. After screening, 614 papers were retained for statistical analysis. A retrospective study was the most used design (44%). A definition of RML was stated in 231 studies (37.6%), including a precise creatine kinase level (CK) cut-off most frequently (67.1%). In 53/231 (22.9%) studies the CK cut-off was > 5 × upper limit of normal (ULN), and in 64/231 (27.7%) studies > 1000 IU/L. Further components of definitions were elevated CK without specific thresholds, and clinical symptoms. Exclusion criteria referring to the definition of RML were established in 113 studies, including myocardial, renal, cerebral and neuromuscular characteristics. CONCLUSION: At present, we recommend a clinical syndrome of acute muscle weakness, myalgia, and muscle swelling combined with a CK cut-off value of > 1000 IU/L/ or CK > 5 × ULN for the standard definition of a mild RML. Additionally measured myoglobinuria and AKI indicate a severe type of RML. Exclusion criteria as well as the chronological sequence need to be considered for a conclusive RML definition.