The MetaBolomiX™ Neuro is a specialized diagnostic panel designed to assess biochemical markers related to neurotransmitter metabolism and tryptophan degradation in the body. This test provides insight into the metabolic pathways that influence neurological function, particularly those related to catecholamine and serotonin metabolism, as well as the kynurenine pathway. The analysis includes the measurement of key metabolites such as vanillylmandelic acid (VMA), homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), tryptophan, xanthurenic acid, L-kynurenine, kynurenic acid, quinolinic acid, and the calculated ratios L-kynurenine/tryptophan and kynurenic acid/L-kynurenine. These biomarkers play a crucial role in neurotransmitter balance, neuroinflammation, and oxidative stress, making the test valuable in investigating conditions associated with neurodegenerative diseases, mood disorders, and metabolic dysfunctions affecting brain chemistry.
Vanillylmandelic acid (VMA) and homovanillic acid (HVA) serve as end products of catecholamine metabolism, reflecting the degradation of epinephrine, norepinephrine, and dopamine. Elevated levels of VMA and HVA may indicate excessive catecholamine turnover, which is often observed in conditions such as stress-related disorders and certain neuroendocrine tumors. Conversely, low concentrations can be indicative of impaired neurotransmitter synthesis or metabolism, potentially associated with neurodegenerative conditions such as Parkinson’s disease. The measurement of these metabolites indirectly assesses dopamine and adrenergic function, which are essential for motor control, cognitive performance, and emotional regulation.
5-Hydroxyindoleacetic acid (5-HIAA) represents the primary metabolite of serotonin, a neurotransmitter involved in mood regulation, cognitive function, and sleep-wake cycles. The serotoninergic system plays a fundamental role in maintaining emotional stability, and alterations in serotonin metabolism are linked to mood disorders, anxiety, and depression. Low levels of 5-HIAA in urine may suggest a deficiency in serotonin synthesis or increased central nervous system utilization, which has been implicated in psychiatric disorders and neurodegenerative diseases such as Alzheimer’s disease. Increased excretion of 5-HIAA may be observed in conditions associated with excessive serotonin turnover, such as carcinoid syndrome.
Tryptophan, an essential amino acid, is a precursor for serotonin and the kynurenine pathway. The balance between serotonin production and kynurenine metabolism is critical for neuroimmune function and cognitive health. The breakdown of tryptophan through the kynurenine pathway results in metabolites such as L-kynurenine, kynurenic acid, and quinolinic acid. Inflammatory signals highly regulate this pathway, and disruptions in tryptophan metabolism have been associated with neurological disorders, immune dysfunction, and psychiatric conditions.
Xanthurenic acid and L-kynurenine are intermediate metabolites in the kynurenine pathway, and their presence provides valuable information about the body’s inflammatory and oxidative stress status. Xanthurenic acid accumulation has been linked to vitamin B6 deficiency, which affects neurotransmitter synthesis and energy metabolism. Elevated L-kynurenine levels are often associated with chronic inflammation, as the enzyme indoleamine 2,3-dioxygenase (IDO) is upregulated in response to pro-inflammatory cytokines, diverting tryptophan metabolism away from serotonin production and toward kynurenine synthesis.
Kynurenic acid and quinolinic acid play opposing roles in neuroprotection and neurotoxicity. Kynurenic acid acts as an antagonist at NMDA receptors and is involved in neuroprotection by reducing excitotoxicity. However, excessive kynurenic acid levels have been associated with cognitive impairment and schizophrenia-like symptoms due to its role in modulating glutamatergic neurotransmission. Quinolinic acid, on the other hand, is a potent neurotoxin that promotes oxidative stress and excitotoxic damage through NMDA receptor activation. Elevated levels of quinolinic acid have been implicated in neuroinflammatory conditions, such as multiple sclerosis, depression, and neurodegenerative diseases. The kynurenine pathway is crucial in understanding the biochemical basis of neuroinflammation, and imbalances between kynurenic acid and quinolinic acid provide insights into underlying pathological processes.
The L-kynurenine/tryptophan ratio indicates IDO enzyme activity, which is upregulated in response to inflammatory conditions. A higher ratio suggests increased tryptophan degradation through the kynurenine pathway, often observed in chronic immune activation and neurodegenerative diseases. This ratio provides a functional measure of systemic inflammation and is valuable in identifying metabolic disturbances linked to neurological and psychiatric conditions. Similarly, the kynurenic acid/L-kynurenine ratio reflects the relative activity of the kynurenine aminotransferases responsible for converting kynurenine into its neuroprotective form. A low ratio may indicate an imbalance favoring neurotoxic quinolinic acid production, contributing to neuronal damage and cognitive decline.
The MetaBolomiX® Neuro provides a comprehensive metabolic profile that aids in understanding neurochemical imbalances, neurotransmitter metabolism, and the impact of inflammation on brain function. The intricate relationships between these biochemical markers offer valuable insights into the pathophysiology of neurological and psychiatric conditions, supporting a deeper understanding of how metabolic dysfunction influences brain health.
