Quinolinate
Overview
Quinolinate, also known as quinolinic acid, is a neuroactive metabolite in the kynurenine pathway of tryptophan catabolism, measured primarily in cerebrospinal fluid, plasma, or urine. It functions as a potent NMDA receptor agonist, contributing to excitotoxicity and neuroinflammation in the central nervous system. Elevated levels indicate neuroinflammatory conditions, neurodegeneration, or infections like HIV encephalopathy, while low levels have limited clinical interpretation; it serves as a research biomarker for monitoring disease activity in neurological disorders where evidence from human studies shows correlation with pathology severity.
Clinical Use Cases
- Research assessment of neuroinflammation in multiple sclerosis and Alzheimer's disease.
- Monitoring HIV-associated neurocognitive disorders.
- Investigating excitotoxic mechanisms in stroke and traumatic brain injury.
- Studying progression in Huntington's and Parkinson's diseases.
- Evaluating kynurenine pathway dysregulation in psychiatric conditions.
Specimen Types
- Cerebrospinal fluid (preferred for CNS evaluation).
- Plasma.
- Serum.
- Urine.
Measurement Methods
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS).
- High-performance liquid chromatography (HPLC) with electrochemical detection.
- Gas chromatography-mass spectrometry (GC-MS).
Test Preparation and Influencing Factors
- No fasting required.
- Prompt freezing of samples at -80°C to prevent degradation.
- Levels influenced by systemic inflammation, infections, or interferon-gamma.
- Tryptophan supplementation or pathway inhibitors may alter concentrations.
- Diurnal variation and renal function affect plasma measurements.
Synonyms
- Quinolinic acid.
- QUIN.
- 2,3-Pyridinedicarboxylic acid.