Serum neuron-specific enolase - reference interval in Danish children and the impact of preanalytical factors.

Objectives: Neuron-specific enolase (NSE) is a clinically relevant biomarker used in the assessment of neuronal damage and in the diagnosis and monitoring of certain cancers. Despite its diagnostic importance, paediatric-specific reference intervals (RIs) for NSE are currently lacking. This study aimed to establish paediatric RIs for NSE in serum and to evaluate the influence of preanalytical factors on NSE measurements.

Methods: Residual serum samples from routine allergy testing in 242 Danish children (aged 0.1-17.9 years) were analysed using the Roche Elecsys^® NSE assay on a Cobas platform. Both traditional non-parametric, age-partitioned RIs and continuous RIs derived via quantile regression were established. In addition, we assessed the impact of preanalytical variables, including haemolysis, and evaluated a previously proposed correction method for haemolysed samples within this cohort.

Results: Both the non-parametric and continuous approaches yielded consistent RIs, showing an age-dependent decline in serum NSE concentrations irrespective of sex. The traditional age-partitioned RI (95th percentile, one-sided) indicated upper limits of 36.9 μg/L and 32.0 μg/L for the age groups 0-5 and 6-17 years of age, based on samples with haemolysis <10 mg/dL haemoglobin.

Conclusions: This study defines age-specific paediatric RIs for serum NSE, demonstrating a physiological decline with age and highlighting higher NSE levels in healthy children compared to adults. Furthermore, within a limited range, a previously proposed simple linear correction method was validated for adjusting NSE values in mildly haemolysed samples using the newly established RIs.