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An audit of holotranscobalamin ("Active" B12) and methylmalonic acid assays for the assessment of vitamin B12 status: application in a mixed patient population.
Clin Biochem. 2014 Jan; 47(1-2):82-6.CB

Abstract

BACKGROUND

Vitamin B12 insufficiency/deficiency is common in mixed patient populations. However there is no single marker which can reliably diagnose B12 insufficiency/deficiency. Elevated concentrations of methylmalonic acid (MMA) are considered the most representative marker of metabolic vitamin B12 insufficiency, but poor assay availability limits clinical utility. Low concentrations of serum vitamin B12 are often used to assess vitamin B12 status but this approach generates a high rate of false negative results. Emerging evidence indicates that holotranscobalamin (holoTC) may be a more reliable indicator of vitamin B12 status.

AIMS AND METHODS

We substituted serum vitamin B12 measurement with holoTC, supported by MMA in patients referred for assessment of vitamin B12 status. A service evaluation was undertaken of the pattern of MMA values obtained for patients with holoTC 25-50 pmol/L (an indeterminate result). MMA cut-offs of 280 and 360 nmol/L were applied for patients ≤ 65 or >65 years respectively.

RESULTS

A total of 4,175 consecutive patients were investigated and MMA was analysed for 19% of patients. The incidence of elevated MMA was 41% (holoTC, 25-29 pmol/L), 32% (30-34 pmol/L), 33% (35-39 pmol/L), 30% (40-44 pmol/L), and 26% (45-50 pmol/L).

CONCLUSIONS

Our results indicate that in the clinical setting a holoTC between 25 and 50 pmol/L is a poor predictor for the concentration of MMA provided the goal is to identify patients with MMA values above the limits used in the present study. Further studies are needed to evaluate to what extent holoTC <25 and >50 pmol/L reflect circulatory MMA concentrations.

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Authors+Show Affiliations

Sobczyńska-Malefora A
The Nutristasis Unit, GSTS Pathology (part of King's Healthcare Partners), St. Thomas' Hospital, London, UK. Electronic address: agata.malefora@gsts.com.
Gorska R
The Nutristasis Unit, GSTS Pathology (part of King's Healthcare Partners), St. Thomas' Hospital, London, UK.
Pelisser M
The Nutristasis Unit, GSTS Pathology (part of King's Healthcare Partners), St. Thomas' Hospital, London, UK.
Ruwona P
The Nutristasis Unit, GSTS Pathology (part of King's Healthcare Partners), St. Thomas' Hospital, London, UK.
Witchlow B
Laboratory Informatics, GSTS Pathology (part of King's Healthcare Partners), St. Thomas' Hospital, London, UK.
Harrington DJ
The Nutristasis Unit, GSTS Pathology (part of King's Healthcare Partners), St. Thomas' Hospital, London, UK.

MeSH

BiomarkersHumansMethylmalonic AcidTranscobalaminsVitamin B 12

Pub Type(s)

Journal Article

Language

eng

PubMed ID

23965230

Citation

Sobczyńska-Malefora, Agata, et al. "An Audit of Holotranscobalamin ("Active" B12) and Methylmalonic Acid Assays for the Assessment of Vitamin B12 Status: Application in a Mixed Patient Population." Clinical Biochemistry, vol. 47, no. 1-2, 2014, pp. 82-6.
Sobczyńska-Malefora A, Gorska R, Pelisser M, et al. An audit of holotranscobalamin ("Active" B12) and methylmalonic acid assays for the assessment of vitamin B12 status: application in a mixed patient population. Clin Biochem. 2014;47(1-2):82-6.
Sobczyńska-Malefora, A., Gorska, R., Pelisser, M., Ruwona, P., Witchlow, B., & Harrington, D. J. (2014). An audit of holotranscobalamin ("Active" B12) and methylmalonic acid assays for the assessment of vitamin B12 status: application in a mixed patient population. Clinical Biochemistry, 47(1-2), 82-6. https://doi.org/10.1016/j.clinbiochem.2013.08.006
Sobczyńska-Malefora A, et al. An Audit of Holotranscobalamin ("Active" B12) and Methylmalonic Acid Assays for the Assessment of Vitamin B12 Status: Application in a Mixed Patient Population. Clin Biochem. 2014;47(1-2):82-6. PubMed PMID: 23965230.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - An audit of holotranscobalamin ("Active" B12) and methylmalonic acid assays for the assessment of vitamin B12 status: application in a mixed patient population. AU - Sobczyńska-Malefora,Agata, AU - Gorska,Renata, AU - Pelisser,Michel, AU - Ruwona,Patricia, AU - Witchlow,Bernie, AU - Harrington,Dominic J, Y1 - 2013/08/18/ PY - 2013/03/06/received PY - 2013/08/08/revised PY - 2013/08/11/accepted PY - 2013/8/23/entrez PY - 2013/8/24/pubmed PY - 2014/8/5/medline KW - Holotranscobalamin KW - Methylmalonic acid KW - Reference ranges KW - Renal function KW - Vitamin B(12) KW - “Active” vitamin B(12) SP - 82 EP - 6 JF - Clinical biochemistry JO - Clin Biochem VL - 47 IS - 1-2 N2 - BACKGROUND: Vitamin B12 insufficiency/deficiency is common in mixed patient populations. However there is no single marker which can reliably diagnose B12 insufficiency/deficiency. Elevated concentrations of methylmalonic acid (MMA) are considered the most representative marker of metabolic vitamin B12 insufficiency, but poor assay availability limits clinical utility. Low concentrations of serum vitamin B12 are often used to assess vitamin B12 status but this approach generates a high rate of false negative results. Emerging evidence indicates that holotranscobalamin (holoTC) may be a more reliable indicator of vitamin B12 status. AIMS AND METHODS: We substituted serum vitamin B12 measurement with holoTC, supported by MMA in patients referred for assessment of vitamin B12 status. A service evaluation was undertaken of the pattern of MMA values obtained for patients with holoTC 25-50 pmol/L (an indeterminate result). MMA cut-offs of 280 and 360 nmol/L were applied for patients ≤ 65 or >65 years respectively. RESULTS: A total of 4,175 consecutive patients were investigated and MMA was analysed for 19% of patients. The incidence of elevated MMA was 41% (holoTC, 25-29 pmol/L), 32% (30-34 pmol/L), 33% (35-39 pmol/L), 30% (40-44 pmol/L), and 26% (45-50 pmol/L). CONCLUSIONS: Our results indicate that in the clinical setting a holoTC between 25 and 50 pmol/L is a poor predictor for the concentration of MMA provided the goal is to identify patients with MMA values above the limits used in the present study. Further studies are needed to evaluate to what extent holoTC <25 and >50 pmol/L reflect circulatory MMA concentrations. SN - 1873-2933 UR - https://www.unboundmedicine.com/medline/citation/23965230/An_audit_of_holotranscobalamin__"Active"_B12__and_methylmalonic_acid_assays_for_the_assessment_of_vitamin_B12_status:_application_in_a_mixed_patient_population_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0009-9120(13)00385-8 DB - PRIME DP - Unbound Medicine ER -