Vitamin B6 is a water-soluble vitamin which comprises pyridoxine, pyridoxal and their 5-phosphate esters. Pyridoxal 5-phosphate (PLP) is the active co-enzyme form of vitamin B6 required for many reactions of amino acid metabolism. Deficiency may occur in the diet, or due to drugs, eg. isoniazid or penicillamine. Symptoms of deficiency include skin hyperpigmentation, tongue swelling, depression and irritability.
Suspected deficiency in malabsorption syndromes and in patients on parenteral nutrition.
EDTA (lavender top)
Up to 6 weeks
Not currently performed in house; this is a referred test.