Relationship between the Levels of Holotranscobalamin and Vitamin B12

Kwang-Sook Woo; Kyung-Eun Kim; Joon-Seok Park; Joo-In Park; Jin-Yeong Han

doi:10.3343/kjlm.2010.30.2.185

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Woo, Kim, Park, Park, and Han: Relationship between the Levels of Holotranscobalamin and Vitamin B12

Brief Communication

Korean J Leg Med 2010;30(2):185-189.

Published online: 14 January 2010

DOI: https://doi.org/10.3343/kjlm.2010.30.2.185

Relationship between the Levels of Holotranscobalamin and Vitamin B12

Kwang-Sook Woo, M.D.¹, Kyung-Eun Kim, M.D.¹, Joon-Seok Park, M.D.², Joo-In Park, Ph.D.³, Jin-Yeong Han, Ph.D.^1,³

¹Department of Laboratory Medicine, Dong-A University College of Medicine, Busan, Korea

²Department of Abbott Korea Ltd., Seoul, Korea

³Medical Research Center Molecular Therapy, Dong-A University, Busan, Korea

Corresponding author: Jin-Yeong Han, Ph.D. Department of Laboratory Medicine, Dong-A University College of Medicine, 1 Dongdaesin-dong 3-ga, Seo-gu, Busan 602-715, Korea Tel: +82-51-240-5323 Fax: +82-51-255-9366 E-mail: jyhan@dau.ac.kr

^∗ This study was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) (R13-2002-044-05002-0).

Revised 5 July 20094 February 2010 Accepted 19 March 2010

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

To date, the determination of serum vitamin B12 levels has been the most common laboratory test for the assessment of vitamin B12 status; however, the diagnostic accuracy of this test is low. To obtain a more sensitive marker, a new test to measure holotranscobalamin (holoTC) levels has been introduced. In this study, we assessed 45 patients for whom a vitamin B12 test had been requested and 139 anemic patients. We investigated the associations between the levels of homocysteine (Hcy) and those of holoTC, serum vitamin B12, and folate and assessed the diagnostic value of holoTC levels as a marker for vitamin B12 deficiency. We also determined the precision of the AxSYM holoTC assay by calculating the coefficient of variance (CV). The within-run and between-run precision values were excellent, as all CV values were less than 3.5%. The holoTC levels were low (<35 pmol/L) in 7 samples, and 6 of these samples had normal total serum vitamin B12 levels. In 2 of these samples, high Hcy levels (>12 mmol/L) indicated vitamin B12 deficiency. Thus, the holoTC levels were more sensitive than the serum vitamin B12 levels for indicating vitamin B12 status. If the serum vitamin B12 level is 151-300 pmol/L, the levels of holoTC alone or in combination with serum vitamin B12 levels are likely to be more useful markers than serum vitamin B12 levels alone.

Keywords: Holotranscobalamin, Vitamin B12 deficiency, Vitamin B12, Homocysteine

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Table 1.

Demographic data and laboratory results of the 184 patients∗

Variables	Patients (N=184)
Sex (female/male)	90/94
Age	61.5 (22-83)
Results of laboratory tests
Vitamin B12 (pmol/L)	564.7 (115.0-1,475.0)
HoloTC (pmol/L)	22.0-128.0^†
Hcy (mmol/L)	9.2 (3.0-50.0)
Folate (mg/L)	6.4 (0.8-48.0)

^∗ Data are presented as median (range) unless otherwise noted;

^† Data are presented as ranges because samples with high levels of holoTC (>128.0 pmol/L) were not diluted.

Abbreviations: holoTC, holotranscobalamin; Hcy, homocysteine.

Table 2.

Results of the precision analysis for the AxSYM holoTC assay, which was performed using low and high controls

Material	Within-run		Between-run		Between-day		Total
Material	SD	CV (%)	SD	CV (%)	SD	CV (%)	SD	CV (%)
Low	0.5	2.9	0.5	2.5	0.7	3.8	1.0	5.5
(21.0 pmol/L)
High	1.4	3.3	0.4	1.1	2.4	5.7	2.9	6.7
(48.0 pmol/L)

Abbreviations: holoTC, holotranscobalamin.

Table 3.

Classification of patients (N=184) according to the holo-TC levels and total serum vitamin B12 ranges (P<0.0001)

Total serum vitamin B12 (pmol/L)	HoloTC<35 pmol/L	HoloTC≥35 pmol/L
100-150	1	0
151-300	4	20
>301	2	157

Abbreviations: holoTC, holotranscobalamin.

Table 4.

Number of patients (N=55) with hyperhomocysteinemia (>12 mmol/L), which was determined to the levels of holoTC and folate

	HoloTC<35.0 pmol/L	HoloTC>35.0 pmol/L	Total
Folate < 3.0 mg/L	0	10	10
Folate > 3.0 mg/L	2	43	45
Total	2	53	55

Abbreviations: holoTC, holotranscobalamin.

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