Neuron-specific enolase correlates to laboratory markers of haemolysis in patients on long-term circulatory support

Objectives: Neuron-specific enolase (NSE) is used as a diagnostic tool in neuropathies, cerebral diseases or traumata and for some tumours. Furthermore, it is also expressed by erythrocytes and platelets and has been linked to haemolysis ex vivo as a laboratory issue. Chronic haemolysis is frequently associated with mechanical circulatory support by ventricular assist device (VAD) or total artificial heart (TAH). Therefore, we compared NSE with indicators of haemolysis in VAD and TAH patients.

Methods: We included 599 data sets of 97 patients who underwent VAD or TAH implantation. NSE, haptoglobin (HAPT), haemopexin (HPX), free haemoglobin (frHB), lactate dehydrogenase activity (LDH), platelet counts and total bilirubin (TBIL) in plasma were analysed. Further, all major cerebral events were assessed.

Results: NSE correlated to frHB (rs = 0.553) and to LDH (rs = 0.695). An inverse correlation was found with HAPT (rs = -0.484) and HPX (rs = -0.398). Thirty-two patients suffered neurological events. Within the time frame of 1 day before to 4 days after a neurological event, correlations of NSE to HAPT (rs = -0.540) and HPX (rs = -0.611) in negative and to frHB (rs = 0.757), LDH (rs = 0.862) and TBIL (rs = 0.549) in positive direction were established (all P < 0.05). Furthermore, haemolysis was graded into three groups for severe, moderate or no or only slight haemolysis. NSE values differed correspondingly between these groups (P < 0.001).

Conclusion: NSE correlates to laboratory parameters indicative of haemolysis in VAD and TAH patients. Our data suggest an influence of intravascular haemolysis on NSE. Therefore, the parameter should be used with caution when it is used to assess cerebral damage.