Vitamin B6 is a generic term that refers to the pyridine-based compounds pyridoxine, 4-pyridoxic acid, pyridoxamine, pyridoxal, and their phosphorylated derivatives. Pyridoxal-5'-phosphate (PLP) is the biologically active form and serves as a cofactor for more than 140 different enzyme reactions. PLP is measured in this assay.
Deficiencies can occur in people with mutations of pyridoxal kinase or pyridoxine 5'-phosphate oxidase, as well as in individuals who are pregnant, have kidney disease, are severely malnourished, or have malabsorption. Additionally, deficiencies have been observed with the usage of certain drugs such as isoniazid, penicillamine, benserazide, and carbidopa. Vitamin B6 deficiency is associated with symptoms of scaling of the skin, severe gingivitis, irritability, weakness, depression, dizziness, peripheral neuropathy, and seizures. In the paediatric population, deficiencies have been characterized by diarrhoea, anaemia, and seizures.
Conversely, exceptionally high levels of vitamin B6 can also have toxic effects resulting in sensory and motor neuropathies. Chronicity and dose of supplementation, specific vitamer, and inter-individual differences in sensitivity to B6 toxicity may all contribute to development of peripheral neuropathy from excess B6. Markedly elevated PLP in conjunction with low or normal levels of pyridoxic acid are observed in cases of hypophosphatasia, a disorder caused by loss-of-function mutation(s) of the gene ALPL that encodes the tissue-nonspecific isoenzyme of alkaline phosphatase.
Lipids/Trace Metals
VB6
1 x EDTA (lavender), wrap in foil, send to lab immediately
Send whole blood to trace metals - freezer.
Do not separate.
Must be whole blood unless by specific arrangement.
Whole blood, frozen 29 days, light protected
PLP
Pyridoxal 5 Phosphate
Pyridoxine
3 weeks
3497