Utility of measuring vitamin B12 and its active fraction, holotranscobalamin, in neurological vitamin B12 deficiency syndromes

Schrempf, Wiebke; Neumeister, Volker; Eulitz, Marco; Siegert, Gabriele; Reichmann, Heinz; Bergmann, SR; Storch, Amanda Sampaio

doi:10.1055/s-0029-1238490

Cited by 7 publications

(11 citation statements)

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“…Most of these studies used an elevated MMA and possibly tHcy concentration to identify individuals with and without vitamin B-12 deficiency ( Table 2 ). All the studies shown in Table 2 involved patients with normal kidney function, and all but one of these studies showed that holoTC's performance is better than that of vitamin B-12, independent of the cutoff MMA value they used to classify patients’ vitamin B-12 status ( 32 , 56 – 59 ). The one study that showed that vitamin B-12 was superior to holoTC included very few patients for assessment of holoTC ( 59 ).…”

Section: Usefulness Of Holotc Measurementmentioning

confidence: 99%

“…All the studies shown in Table 2 involved patients with normal kidney function, and all but one of these studies showed that holoTC's performance is better than that of vitamin B-12, independent of the cutoff MMA value they used to classify patients’ vitamin B-12 status ( 32 , 56 – 59 ). The one study that showed that vitamin B-12 was superior to holoTC included very few patients for assessment of holoTC ( 59 ). The few studies in patients with impaired kidney function showed that holoTC is also superior in these patients ( 56 , 58 ).…”

Section: Usefulness Of Holotc Measurementmentioning

confidence: 99%

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Holotranscobalamin, a marker of vitamin B-12 status: analytical aspects and clinical utility

Nexø

Hoffmann-Lücke

2011

The American Journal of Clinical Nutrition

205

152

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Approximately one-quarter of circulating cobalamin (vitamin B-12) binds to transcobalamin (holoTC) and is thereby available for the cells of the body. For this reason, holoTC is also referred to as active vitamin B-12. HoloTC was suggested as an optimal marker of early vitamin B-12 deficiency >20 y ago. This suggestion led to the development of suitable assays for measurement of the compound and clinical studies that aimed to show the benefit of measurement of holoTC rather than of vitamin B-12. Today holoTC can be analyzed by 3 methods: direct measurement of the complex between transcobalamin and vitamin B-12, measurement of vitamin B-12 attached to transcobalamin, or measurement of the amount of transcobalamin saturated with vitamin B-12. These 3 methods give similar results, but direct measurement of holoTC complex is preferable in the clinical setting from a practical point of view. HoloTC measurement has proven useful for the identification of the few patients who suffer from transcobalamin deficiency. In addition, holoTC is part of the CobaSorb test and therefore useful for assessment of vitamin B-12 absorption. Clinical studies that compare the ability of holoTC and vitamin B-12 to identify individuals with vitamin B-12 deficiency (elevated concentration of methylmalonic acid) suggest that holoTC performs better than total vitamin B-12. To date, holoTC has not been used for population-based assessments of vitamin B-12 status, but we suggest that holoTC is a better marker than total vitamin B-12 for such studies.

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Section: Usefulness Of Holotc Measurementmentioning

confidence: 99%

Section: Usefulness Of Holotc Measurementmentioning

confidence: 99%

Holotranscobalamin, a marker of vitamin B-12 status: analytical aspects and clinical utility

Nexø

Hoffmann-Lücke

2011

The American Journal of Clinical Nutrition

205

152

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“…12,13 Although HoloTC is considered a relatively early biomarker of vitamin B12 deficiency, there is conflicting evidence for its diagnostic performance. 21,22,34…”

Section: Discussionmentioning

confidence: 99%

Functional vitamin B12 deficiency in phenylketonuria patients and healthy controls: An evaluation with combined indicator of vitamin B12 status as a biochemical index

Akış

Kant

Işık³

et al. 2020

Ann Clin Biochem

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Background Vitamin B12 deficiency frequently appears in phenylketonuria patients having a diet poor in natural protein. The aims of this study were to evaluate vitamin B12 status in phenylketonuria patients by using combined indicator of vitamin B12 status (cB12) as well as methylmalonic acid and homocysteine, more specific and sensitive markers, in comparison with healthy controls. Methods Fifty-three children and adolescents with phenylketonuria under dietary treatment and 30 healthy controls were assessed cross-sectionally. Serum vitamin B12 and folate concentrations were analysed by chemiluminescence immunoassay. Plasma methylmalonic acid and total homocysteine concentrations were measured by liquid chromatography-tandem mass spectrometry and liquid chromatography, respectively. cB12 was calculated by using a formula involving blood parameters. Results Methylmalonic acid and folate concentrations in phenylketonuria group were higher compared with controls. Methylmalonic acid concentrations were high in 56.5% of the patients and 26.7% of the controls with normal vitamin B12 concentrations. Based on cB12, a significant difference within the normal values was detected between the groups. However, although 24.5% of phenylketonuria patients and 13.3% of controls had decreased vitamin B12 status according to cB12, there was no significant difference. Conclusion Children and adolescents with phenylketonuria having a strict diet can be at risk of functional vitamin B12 deficiency. This deficiency can be accurately determined by measuring methylmalonic acid concentrations. Calculation of cB12 as a biochemical index did not provide additional information compared with the measurement of methylmalonic acid alone, but may be helpful for classification of some patients with increased methylmalonic acid as having adequate vitamin B12 status.

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“…The sensitivity of elevated serum MMA measurements in detecting patients with overt cobalamin deficiency is reported to be >95%; however, the specificity of this test has not been determined [9,27]. For example, Hvas et al Uncertain [32][33][34][35][36][37] Levels may be affected by: Liver disease Macrophage activation Autoantibodies [6] did not find any correlation between elevated plasma levels of MMA and clinical manifestations of cobalamin deficiency even after controlling for patients with renal disease. Moreover, this study of 432 untreated patients with modestly elevated MMA levels, who did not exhibit signs or symptoms of cobalamin deficiency showed MMA levels that spontaneously declined in 44% and increased in 16%, demonstrating considerable biological and temporal variability.…”

Section: Measurement and Clinical Utility Of Mma And Hcy Levelsmentioning

confidence: 99%

“…Although initial studies of the sensitivity of holotranscobalamin for detecting cobalamin deficiency appears to slightly improve on that of direct total cobalamin measurements, studies have suggested that the specificity of holotranscobalamin measurements to detect cobalamin deficiencies remains low [33,37]. Problems remain in defining a gold standard test and definition of cobalamin deficiency with which to compare new assays to.…”

Section: Measurement and Clinical Utility Of Holotranscobalamin Levelsmentioning

confidence: 99%

Laboratory testing for cobalamin deficiency in megaloblastic anemia

Oberley

Yang

2013

American J Hematol

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Cobalamin (vitamin B12) deficiency is a common cause of megaloblastic anemia in Western populations. Laboratory evaluation of megaloblastic anemia frequently includes the assessment of patient cobalamin and folate status. Current total serum cobalamin measurements are performed in the clinical laboratory with competitive binding luminescence assays, whose results may not always accurately reflect actual cobalamin stores. Surrogate markers of cobalamin deficiency such as methylmalonic acid and homocysteine have been utilized to improve diagnostic accuracy; however, the specificity of these tests by themselves is rather low. Measurement of the biologically active fraction of cobalamin, holotranscobalamin, has been proposed as a replacement for current total cobalamin assays. Although holotranscobalamin measurements appear to have slighter better sensitivity, the specificity of this assay remains to be determined. The relative merits and demerits of commonly available methods to assess cobalamin deficiency in patients with suspected megaloblastic anemia are discussed. Am. J. Hematol. 88:522–526, 2013. © 2013 Wiley Periodicals, Inc.

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Utility of measuring vitamin B12 and its active fraction, holotranscobalamin, in neurological vitamin B12 deficiency syndromes

Cited by 7 publications

References 0 publications

Holotranscobalamin, a marker of vitamin B-12 status: analytical aspects and clinical utility

Holotranscobalamin, a marker of vitamin B-12 status: analytical aspects and clinical utility

Functional vitamin B12 deficiency in phenylketonuria patients and healthy controls: An evaluation with combined indicator of vitamin B12 status as a biochemical index

Laboratory testing for cobalamin deficiency in megaloblastic anemia

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