Test Database

Description

PLP can be measured either in serum, plasma or whole blood. All are valid matrices for the assessment of B6 status in many patients. However, serum and plasma PLP concentrations are subject to changes in acute phase response. Because of this, it is preferable that PLP is measured in whole blood. A Gerstel Multi Purpose Sampler coupled with liquid chromatography and electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS) is used for the analysis of pyridoxal-5'-phosphate. Due to the relocation of the Nutristasis service to the Blackfriars Hub site, this test is not currently accredited by UKAS to ISO15189

Clinical details

Vitamin B6 in food can be found mainly as the three 5'-phosphate ester forms with particularly high concentrations in yeast extract, wheat bran and liver. Once absorbed vitamin B6 is transported to the liver where the various forms are converted to the physiologically active form, pyridoxal-5'-phosphate (PLP), by pyridoxal kinase. The roles of vitamin B6 in the human body include; amino acid metabolism, homocysteine metabolism, porphyrin biosynthesis, nucleic acid biosynthesis, glycogenolysis, lipid metabolism, steroid hormone regulation and maintenance of the immune system. Symptoms of deficiency are thought to be gastrointestinal disturbances and epithelial changes. However as B6 is so widespread in foods it would be expected that deficiency in B6 would be accompanied by a concomitant deficiency in other water soluble vitamins thus making it difficult to differentiate between the symptoms of the various deficiencies. High vitamin B6 intake is known to be toxic.

Related condition

Vitamin B6 deficiency

Reference range

44-168 nmol/L

Units

nmol/L

Synonyms

Pyridoxal; Pyridoxal-5'-phosphate

Testing site

Synnovis : Reference Services : Blackfriars Hub

Laboratory

Nutristasis Unit