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Test Name:
Vitamin B12 Deficiency Panel
- SBMF No:
42600 - Performance Lab Name:
Metabolite Laboratories, Inc. - Test Mnemonic:
B12DEF PAN - ABN:
Not required - CPT Code:
82136; 83921x2 - LOINC Code:
19146-0 - Ref Lab Test No:
Quest# S41055 - Test Includes:
Methylmalonic Acid
2-Methylcitric Acid
Homocysteine
Cystathionine - Also Known As:
Anemia Profile, Megaloblastic, Serum
Megaloblastic Anemia Panel - Also See:
30144 Homocysteine, Total, Serum
31403 Methylmalonic Acid, Serum
30040 Vitamin B12 with Serum Folate - Spec Type:
Serum - Spec Container:
Red top - Pref Vol:
1.0 mL - Min Vol:
0.5 mL - Fasting:
No - Spec Collect:
Routine venipuncture - Spec Process:
Clot 30 minutes
Promptly centrifuge 15 minutes
Immediately transfer serum to separate plastic tube and freeze - Spec Store Transport:
Frozen - Spec Stability:
Room temperature (20-30°C): Unacceptable
1 week refrigerated (2-8°C)
Greater than 1 week, freeze (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles - Spec Reject:
Thawed sample - Methodology:
Gas Chromatography/Mass Spectrometry (GC/MS) - Use:
Diagnosing and distinguishing between B12 and folate deficiency - Reference Range:
- Methylmalonic Acid
- 73-271 nmol/L
- 2-Methylcitric Acid
- 60-228 nmol/L
- Homocysteine
- 5.1-13.9 umol/L
- Cystathionine
- 44-342 nmol/L
- Interpretive Data:
NORMAL B12 DEFICIENCY FOLATE DEFICIENCY %HIGH %HIGH %HIGH Metabolite - 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 - Notes:
- 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.
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.
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.
Serum metabolite levels can be rechecked 5 to 15 days after vitamin therapy.
Normal ranges 6 hours post oral Methionine load (100 mg L-Methionine/kg body wt.) are as follows: Homocysteine 16.5-45.7 umol/L and Cystathionine 424-2500 nmol/L. Methylmalonic Acid and 2-Methylcitric Acid do not change after a Methionine load.
- Additional Test Info:
This test is referred through Quest Diagnostics Nichols Institute. - Day Run:
Mon, Thu - Time Reported:
Within 9 days - Test Type:
CHEMISTRY
