Sign in →

Test ID FB12V Vitamin B12 Deficiency Panel

Method Name

Gas Chromatography/Mass Spectrometry (GC/MS)

Reporting Name

Vitamin B12 Deficiency Panel

Specimen Type

Varies

Submit only 1 of the following specimens:

 

Preferred

Serum

Draw blood in a plain, red-top tube(s). Serum should be separated from cells within 1 hour from time of collection or kept on ice prior to separation. Pour off 1.0 mL serum into a plastic vial, freeze and ship frozen.

Note:    1. Indicate serum on request form.

            2. Label specimen appropriately (serum).

 

Alternate

Plasma

Draw blood in a heparin (green-top) tube(s).  Plasma should be separated from cells within 1 hour from time of collection or kept on ice prior to separation. Pour off 1 mL plasma into a plastic vial, freeze and ship frozen.

Note:    1. Indicate plasma on request form.

            2. Label specimen appropriately (plasma).

Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time
Varies Frozen (preferred)
  Ambient  24 hours
  Refrigerated 

Reference Values

INTERPRETATION:

                    NORMAL     B12 DEFICIENCY     FOLATE DEFICIENCY

Metabolite    %HIGH                %HIGH                                %HIGH

           RANGE VALUES   RANGE   VALUES      RANGE    VALUES

Methylmalonic Acid:

                      73-271   <3            271-200,000  >95             73-271    <3

2-Methylcitric Acid:

                      60-228   <3             228-15,000   >80              60-228    <3

Homocysteine:

                      5.1-13.9 <3                 14-500       >95             14-250    >95

Cystathionine:

                       44-342  <3             342-4000      >80         342-18,000 >80

    

NOTE 1)Serum Methylmalonic Acid and Homocysteine are the primary metabolic tests for diagnosing and distinguishing between B12 and folate deficiency. They can be used in conjunction with the serum B12 which is usually low or low normal (<350 pg/mL) in B12 deficiency and the serum folate which is usually low or low normal (<5 ng/mL) in folate deficiency. 2-Methylcitric Acid and Cystathionine provide confirmatory evidence for such deficiencies. Homocysteine and especially Cystathionine may also be high in B6 deficiency.

    

NOTE 2) Elevated levels of serum metabolites will correct to normal after treatment with the appropriate vitamin but will not correct after treatment with the wrong vitamin, even in pharmacologic amounts.

    

NOTE 3) Any of the four metabolites can be elevated due to renal insufficiency or intravascular volume depletion. This occurs most commonly in the case of 2-Methylcitric Acid and Cystathionine. Elevated metabolite levels do not correct with B12, folate or B6 treatment unless vitamin deficiency coexists.

 

NOTE 4) Serum metabolite levels can be rechecked 5 to 15 days after vitamin therapy.

    

NOTE 5) Normal ranges 6 hours post oral Methionine load (100 mg L-Methionine/kg body wt.) are as follows: Homocysteine 16.5-45.7 umoles/Liter and Cystathionine 424-2500 nmoles/Liter. Methylmalonic Acid and 2-Methylcitric Acid do not change after a Methionine load.

Day(s) Performed

Monday and Wednesday

Report Available

2 days

Performing Laboratory

Metabolite Laboratories, Inc. Department of Hematology Univ of CO Denver

CPT Code Information

82136/HCYS and cystathionine

83921/ x2 MMA and methylcitric acid

NY State Approved

No