Comparison of neutrophil gelatinase-associated lipocalin in cerebrospinal fluid and serum of dogs with meningoencephalitis of unknown origin and intracranial neoplasia

Objective Neutrophil gelatinase-associated lipocalin (NGAL) is a versatile protein proposed as a marker of renal disease but is also involved in immune response and iron metabolism. Recently, elevated levels of NGAL in cerebrospinal fluid (CSF) of dogs with steroid-responsive meningitis arteriitis and meningoencephalitis of unknown origin (MUO) were detected. Distinction of inflammation and neoplasia in the central nervous system is not always possible using magnetic resonance imaging in dogs and additional biomarkers are needed.

Material and methods We retrospectively measured NGAL levels by use of a previously validated commercial ELISA in CSF and serum of client-owned dogs with MUO (n = 29) and intracranial neoplasia (n = 40) presented between 2016 and 2020. Levels of NGAL in CSF and serum of both patient groups were compared by unpaired t-test. Hypotheses were that levels of NGAL in patients with MUO would be higher than in patients with intracranial neoplasia and that serum- and CSF levels would decrease in patients with MUO under immunomodulatory treatment.

Results Concentration of NGAL was overall significantly higher in serum than in CSF (p < 0.0001). Mean values in CSF were 2.4 ng/ml (range 0.07–16.68 ng/ml) for MUO patients and 0.55 ng/ml (0.17–1.5 ng/ml) in patients with intracranial neoplasia. In serum, mean level of MUO patients was 10.86 ng/ml (2.42–66.95 ng/ml) and 9.37 ng/ml (2.48–36.14 ng/ml) in patients with intracranial neoplasia. Levels of NGAL in CSF were significantly higher in the MUO group compared to patients with intracranial neoplasia (p < 0.05). No significant difference between both groups was detected in serum (p = 0.5260). Levels in CSF of individual dogs with MUO under therapy (n = 7) decreased compared to levels at timepoint of diagnosis in all but one patient.

Conclusion Despite overlap of NGAL CSF-levels in the 2 disease groups, we propose that NGAL adds information to differentiate between inflammatory and neoplastic brain disease and might be one part of the puzzle to establish a diagnosis.

Publication History

Article published online:
15 February 2021