Application of a simple immunoadsorption assay for the measurement of saturated and unsaturated transcobalamin II and R-binders

Lindemans, Jan; Schoester, M.; Kapel, J. Van

doi:10.1016/0009-8981(83)90232-2

Cited by 25 publications

(12 citation statements)

References 22 publications

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“…In our study, the central 95% reference interval for serum holoTC in 303 healthy adults and elderly was 37-171 pmol/L (geometric mean, 79 pmol/L). These values are consistent with the values obtained previously by methods that separate TC from haptocorrin (4,6 ) and also by a new method described by Nexø et al (13 ) in which apoproteins are first separated from holoproteins and then the TC fraction of the holoproteins is directly measured by ELISA.…”

Section: Discussionsupporting

confidence: 92%

“…The majority of the methods described measure holoTC indirectly as the difference between total Cbl and the amount of haptocorrin-bound Cbl. Because the concentrations of these variables are high, a small holoTC value may not be precise (4,5,12 ). Only one in-house method that directly quantifies holoTC has been described previously (6 ), but it is too laborious and imprecise for routine use.…”

mentioning

confidence: 99%

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RIA for Serum Holo-Transcobalamin: Method Evaluation in the Clinical Laboratory and Reference Interval

Loikas

Löppönen²,

Suominen

et al. 2003

Clinical Chemistry

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Section: Discussionsupporting

confidence: 92%

mentioning

confidence: 99%

RIA for Serum Holo-Transcobalamin: Method Evaluation in the Clinical Laboratory and Reference Interval

Loikas

Löppönen²,

Suominen

et al. 2003

Clinical Chemistry

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“…Our reference interval compares well with previously published values obtained by methods using immunoprecipitation of HC and subsequent measurement of cobalamin or vitamin B 12 analogs bound to HC by assays that used HC as binding protein (8,9 ). The intraindividual variation of total HC (6%) and holoHC (6%) in our study was low compared with previously reported results for cobalamin (9%) and holoTC (16%) (12 ), which most likely reflects that holoHC is a more stable marker over time than is holoTC, as judged from its half-life of more than a week compared with the half-life of TC, which is in the magnitude of hours (2 ).…”

Section: Discussionsupporting

confidence: 84%

Effect of Vitamin B12 Treatment on Haptocorrin

et al. 2006

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“…The present study measures TC I/HC with a RIA that quantifies total TC I/HC directly. The reference interval for this RIA was comparable to but slightly lower (20 ) than the intervals for two reported additive methods of determining total TC I/HC (21,22 ). As presaged in a preliminary abstract of part of the data (23 ), the findings reported here suggest that mild TC I/HC deficiency is relatively common and is responsible for many otherwise unexplained low cobalamin concentrations.…”

supporting

confidence: 58%

“…As discussed elsewhere (20 ), most assays of TC I/HC have measured its ability to bind cobalamin added in vitro, thus detecting only unsaturated apo-TC I/HC. However, cobalamin-saturated holo-TC I/HC usually exceeds apo-TC I/HC in plasma (21,22 ), which limits the informativeness of measurements of apo-TC I/HC alone. The present study measures TC I/HC with a RIA that quantifies total TC I/HC directly.…”

mentioning

confidence: 99%

Mild Transcobalamin I (Haptocorrin) Deficiency and Low Serum Cobalamin Concentrations

Carmel

2003

Clinical Chemistry

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Background: Low cobalamin concentrations are common, but their causes are often unknown. Transcobalamin I/haptocorrin (TC I/HC) deficiency, viewed as a rare cause, has not been examined systematically in patients with unexplained low serum cobalamin. Methods: Total TC I/HC was measured by RIA in three subgroups of 367, 160, and 38 patients with different categories of low cobalamin concentrations and three comparison subgroups of 112, 281, and 119 individuals with cobalamin concentrations within the reference interval. Additional studies, including family studies, were done in selected patients found to have low TC I/HC concentrations. Results: Low TC I/HC concentrations suggestive of mild TC I/HC deficiency occurred in 54 of 367 (15%) patients with low cobalamin identified by clinical laboratories and 24 of 160 (15%) patients whose low cobalamin was unexplained after absorption and metabolic evaluation, but in only 2 of 38 patients with malabsorptive causes of low cobalamin concentrations (5%). The prevalence was only 3% (8 of 281 plasma samples) to 5% (6 of 112 sera) in patients with cobalamin concentrations within the reference interval and 3% (4 of 119) in healthy volunteers. Three patients with low cobalamin (0.6%) had severe TC I/HC deficiency with undetectable TC I/HC. Presumptive heterozygotes for severe TC I/HC deficiency in two families had the findings of mild TC I/HC deficiency; mild deficiency was also found in at least three of seven studied families of patients with mild TC I/HC deficiency. Conclusions: Mild TC I/HC deficiency is frequently associated with low cobalamin, is often familial, and its biochemical phenotype appears identical to the heterozygous state of severe TC I/HC deficiency. Severe TC I/HC deficiency also appears to be more common

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Application of a simple immunoadsorption assay for the measurement of saturated and unsaturated transcobalamin II and R-binders

Cited by 25 publications

References 22 publications

RIA for Serum Holo-Transcobalamin: Method Evaluation in the Clinical Laboratory and Reference Interval

RIA for Serum Holo-Transcobalamin: Method Evaluation in the Clinical Laboratory and Reference Interval

Effect of Vitamin B12 Treatment on Haptocorrin

Mild Transcobalamin I (Haptocorrin) Deficiency and Low Serum Cobalamin Concentrations

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