Lab Dept:


Test Name:

Vitamin B6 Assay

General Information

Lab Order Codes:



Pyridoxal 5-phosphate; PALP

CPT Codes:

84207 – Pyridoxal phosphate (Vitamin B-6)

Test Includes:

Vitaming B6/Pyridoxal 5-Phosphate level reported in mcg/L.


Test Indications:

Useful for determining vitamin B6 status, including persons who present with progressive nerve compression disorders such as carpal tunnel and tarsal tunnel syndromes. Determining the overall success of a vitamin B6 supplementation program. Diagnosis and evaluation of hypophosphatasia.

Lab Testing Sections:

Chemistry - Sendouts

Referred to:

Mayo Medical Laboratories (Mayo Test: PLP/60295)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

2 – 7 days, testing set up Monday - Friday

Special Instructions:

See Container, Collection and Patient Preparation below.


Specimen Type:



Green top (Li heparin) tube

Note: PGT (plasma gel) are not acceptable

Draw Volume:

3 mL (Minimum: 1.5 mL) blood

Processed Volume:

1 mL (Minimum: 0.5 mL) plasma


Routine venipuncture. Protect specimen from light by wrapping in foil. Forward to laboratory promptly.


Special Processing:

Lab Staff: Centrifuge specimen, remove plasma/serum aliquot into an amber MML tube (Supply T192) to protect from light. Store and ship at refrigerated temperatures. Forward promptly.

Patient Preparation:

Vitamin supplements must not be ingested for 24 hours before the specimen is drawn. Alcohol must not be consumed for 24 hours before specimen is drawn. It is recommended that the patient be fasting 12 - 14 hours (overnight fast or infants prior to next draw) before specimen is collected.

Sample Rejection:

Improper patient preparation may yield useless results. Exposure of the specimen to light may result in falsely decreased values. Separator tubes are NOT acceptable. Warm specimens; anticoagulants other than heparin; mislabeled or unlabeled specimens


Reference Range:

5 – 50 mcg/L

Critical Values:



Reference ranges were established using healthy fasting volunteers who abstained from vitamin supplementation for 24 hours prior to draw. Vitamin supplementation and non-fasting specimens may result in elevated plasma vitamin concentrations.


Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)


Mayo Medical Laboratories (April 2011)


7/12/2010: Units update from ug/L to mcg/L.
4/19/2011: Method change, previously listed as Automated reversed phase High Performance Liquid Chromatography (HPLC).