Test not routinely available without prior discussion with the Duty Biochemist (x26922 option 2).
Vitamin B6 is a water-soluble vitamin and is part of the vitamin B complex group. Pyridoxal phosphate (PLP) is the active form and is a cofactor in many reactions of amino acid metabolism, including transamination, deamination, and decarboxylation. It is also necessary for the enzymatic reaction governing the release of glucose from glycogen.
For nutritional status red cell PLP is measured. For investigation and monitoring of hypophosphatasia, plasma PLP and pyridoxic acid (PA) is measured. Very high plasma PLP:PA ratios are observed in cases of hypophosphatasia.
Tube
For assessing vitamin B6 status: Lithium heparin (non-gel) or EDTA. Lithium heparin gel tubes unsuitable.
For investigating hypophosphatasia: EDTA
ID
Tests&Tubes0257
Additional Information
Please contact the lab (x26922 option 2) to discuss before sending the sample to ensure correct processing.
Turn Around
Turnaround time stated by Glasgow Royal Infirmary: 2 weeks.
Send to
Blood Sciences LGI
(Test referred to: Glasgow Royal Infirmary).
Contact
For further details please contact Leeds Pathology customer services: [email protected].
Collection Con
Protect all samples from light (e.g. wrap in foil).
For assessing vitamin B6 status: lithium heparin (no gel) or EDTA tube required. Gel tubes are not suitable. Fasting sample preferred, or 8h post oral supplementation or TPN.
For investigating hypophosphatasia: fasting EDTA sample required.
Lab Instructions:
For all samples, please note whether sample was protected from light in specimen comment. Please protect any unprotected samples.
Different sample processing is required depending on the clinical question.If unsure, please contact the Duty Biochemist.
For vitamin B6: if sample can be sent so as to arrive in Glasgow within 72h of collection, store and send whole blood (ambient), minimum 1 mL. Otherwise, centrifuge, remove plasma and buffy coat, and freeze packed red cells, minimum 400 uL.
For hypophosphatasia: EDTA plasma is required, minimum 600 uL. Separate and freeze plasma. Write ‘plasma PLP/PA ratio’ on request form.
Sample REQ
Blood.
Ref. Range Notes
Red cell PLP: 250-680 pmol/g Hb
<150 pmol/g Hb (at risk of deficiency)
>2000 pmol/g Hb (over supplementation)
>4000 pmol/g Hb (risk of toxicity)
Plasma (for investigation of hypophosphatasia):
PLP: 20 – 140 nmol/L80
PA: 9 – 60 nmol/L80 PLP:PA ratio: <5 (This reference range only applies when the plasma PLP is raised).
Units
pmol PLP/g Hb.