Background:
Standard biomarkers are not yet available for use in clinical practice as part of ALS diagnosis or therapeutic guidance. Neurofilament light chain (NfL), a neuronal cytoplasmic protein, has emerged as a potential marker of axonal damage, offering insights into disease diagnosis and management (Gaetani et al., 2019). However, since serum NfL testing has become commercially available, its use in the clinical setting has not been extensively explored. An understanding of the use of commercial assays and its application to different neurological clinical settings may be valuable.
Objective:
We sought to outline patterns of serum NfL levels obtained via commercial lab testing in our Neurology department patient population, aiming to discern whether there were significant differences between a neurodegenerative disease, ALS, and other types of neuronal disorders.
Methods:
We examined all serum NfL test results ordered by Neuromuscular or Neuroimmunology providers for patients in our clinic through the same commercial laboratory (Labcorp). We assessed patients with four diagnoses, ALS, MS, autoimmune neuropathies, and other neuropathies, evaluating 16 test results in the ALS group, 81 in the MS group, 3 in the autoimmune neuropathies (GBS/CIDP) group, and 118 in the group with other neuropathies. ANOVA and Tukey’s tests were performed to identify any significant differences between these groups.
Results:
The average age within our patient population at the time of NfL testing was 52.5 years. Mean serum NfL levels of ALS patients differed significantly from mean NfL levels of all other groups (ANOVA, F3, 213 = 17.5; p < 0.05). The ALS group mean of 10.6 pg/ml was the only group mean outside the commercial laboratory’s normal reference range for 50-59 year-olds (<3.79 pg/ml). The ALS group had greater mean NfL levels than MS (padj=0), GBS/CIDP (padj=0.019), and other neuropathies (padj=0). The mean Nfl levels in MS, GBS/CIDP, and other neuropathies groups did not differ significantly (padj>0.6).
Discussion/Conclusions:
Our real-world data is consistent with data from clinical trials, indicating patterns of NfL levels in various disease states, with neurodegenerative disorders being associated with higher NfL levels than demyelinating diseases (Gaetani et al., 2019). Commercial serum NfL testing could be a valuable tool particularly for neurologists working with patients with neurodegenerative diseases.