Announcing Xanthurenic and Kynurenic Acids
May 1st, 2018
Meridian Valley Lab now measures Xanthurenic and Kynurenic Acids to provide clinical information regarding the patient’s inflammatory and vitamin B-6 status. The function of the Kynurenine Pathway, which generates Xanthurenic and Kynurenic Acid, is affected by hormone status. A deeper understanding of both of these biomarkers, provided at MVL, provides an “early warning system” and additional layers of interpretation regarding a variety of health risks including blood sugar metabolism, cancer risk, depression, cardiovascular disease, neuroinflammation, rheumatoid arthritis and autoimmunity.
Why test Xanthurenic and Kynurenic Acid?
Xanthurenic (XANA) and Kynurenic Acid (KYNA) are metabolites on the Kynurenine Pathway of tryptophan metabolism. MVL has added Xanthurenic and Kynurenic Acid to its profiles to improve the clinical management of estrogen detoxification. Studies indicate that individuals with low-activity catechol-O-methyltransferase (COMT) may require additional B6, B12 and folate to detoxify pro-carcinogenic estrogen metabolites. While high levels of Xanthurenic and Kynurenic Acid are commonly associated with mild or subclinical B6 deficiency and/or inflammation, the vitamin B2 requirement for XANA synthesis is seldom discussed or acknowledged in other laboratory reports. Additional risks represented by increased levels of XANA or KANA are also rarely discussed, though equally important:
Insulin resistance and diabetes
High levels of XANA may form complexes that block insulin receptors and, over time, destroy pancreatic cells.
Cancer risk
KYNA, and to a lesser extent, XANA both bind to and activate the aryl hydrocarbon receptor (AhR). Activation of the AhR either by environmental toxins (dioxin, etc.) or XANA and KYNA can induce cell damage and carcinogenesis.
Neurologic function
KYNA blocks glutamate from binding with N-methyl-D-aspartate (NMDA) receptors on neurons, which may alter mood or behavior. KYNA also binds to the alpha7-nicotinic acetylcholine receptor important for long-term memory.
Cardiovascular function
Higher XANA levels are associated with cardiovascular disease. Chronic inflammation may increase the amount of circulating tryptophan metabolized outside of the liver. Peripheral metabolism of tryptophan in leucocytes, endothelial cells, macrophages and vascular smooth muscle cells increase risk factors for atherosclerosis in those with elevated LDL-cholesterol, BMI, or triglycerides, particularly in younger women.
Autoimmunity
KYNA levels modulate the production of IL-6 and increased levels of IL-6 are associated with rheumatoid arthritis (RA), systemic-onset juvenile chronic arthritis (JCA), osteoporosis, and psoriasis.
The Kynurenine Pathway metabolizes excess tryptophan and controls hepatic heme synthesis and tryptophan availability for serotonin synthesis. The Kynurenic Pathway also produces immune-regulatory and neuroactive metabolites, nicotinic acid (vitamin B3), and oxidized nicotinamide adenine dinucleotide (NAD+). The primary site of Kynurenic Pathway activity is the liver, where all of the enzymes to metabolize tryptophan into NAD(P)H are found; this accounts for 90% of tryptophan metabolism. Extra-hepatic metabolism of tryptophan increases when the immune system is activated, but not all the pathway enzymes are found outside the liver. Low levels of both Xanthurenic and Kynurenic Acid may indicate a tryptophan deficiency, a liver disorder, or a very rarely, severe B6 deficiency.
Profiles with Xanthurenic and Kynurenic Acids Included
Code |
Profile Name |
Sample Type |
| 4100 | Comprehensive ULTIMATE | 24-Hour Urine |
| 4009 | ComprehensivePLUS w/ Oxytocin | 24-Hour Urine |
| 4090 | ComprehensivePLUS w/ Melatonin | 24-Hour Urine |
| 4078 | ComprehensivePLUS w/ hGH | 24-Hour Urine |
| 4080 | ComprehesivePLUS | 24-Hour Urine |
| 4990 | CompletePLUS | Dried Urine |
| 4992 | Complete Profile | Dried Urine |
| 4470 | Xanthurenic and Kynurenic Acids | 24-Hour Urine |
| 4970 | Xanthurenic and Kynurenic Acids | Dried Urine |
