Venous bicarbonate and creatine kinase as diagnostic and prognostic tools in the setting of acute traumatic rhabdomyolysis

Background. Myorenal or crush syndrome often develops following soft-tissue traumatic injury. It is a spectrum of disease that may result in severe renal dysfunction and kidney injury requiring renal replacement therapy. Objectives. To review a large cohort of patients with so-called myorenal or crush syndrome and assess the biochemical markers of venous bicarbonate and creatine kinase as predictors for the development of acute kidney injury (AKI). Methods. All patients with myorenal syndrome who presented to Khayelitsha District Hospital, Cape Town, South Africa (SA), and Ngwelezana Hospital, Empangeni, KwaZulu-Natal, SA, between January and December 2017 were identified and reviewed. Results. A total of 212 patients were included in the study At both hospitals, 94% of the patients were male. Using the Pearson correlation coefficient, we compared creatinine kinase (CK) against serum creatinine. The mean CK level was 5 311.8 U/L and the mean creatinine level 133.457 mu mol/L. The r-value was 0.2533. Although this is a technically positive correlation, the relationship between the variables is weak. Using the Pearson R Calculator, we inserted the r-value to calculate the p-value. The p-value was 0.000208. When comparing venous bicarbonate (HCO3) against creatinine, the mean HCO3 level was 22.296 mmol/L and the mean creatinine level 162.053 mu mol/L. The r-value was -0.3468. Although this is a technically negative correlation, the relationship between the variables is weak. Using the Pearson R Calculator, we inserted the r-value to calculate the p-value. The p-value was 0.000013. The inverse ratio shown with HCO3 v. creatinine, although still a weak correlation, is significantly better in predicting an increase in creatinine compared with the weak positive correlation of CK v. creatinine. Conclusions. Although both venous HCO3, and CK showed a weak correlation with creatinine, the former performed significantly better in predicting AKI. In a resource-constrained system, we recommend that HCO3 be measured to assess patients with crush injury and that CK be regarded as a complementary modality.

Automated summary

The study found that the negative correlation between venous bicarbonate (HCO3) and creatinine was weak, but significantly better in predicting acute kidney injury compared to the weak positive correlation of creatine kinase (CK) and creatinine. It is recommended in resource-constrained settings to measure HCO3 to assess crush injury patients and consider CK as a complementary modality.