Two radioassays for serum vitamin B12 and folate determination compared in a reference interval study.

1985 ◽  
Vol 31 (8) ◽  
pp. 1358-1360 ◽  
Author(s):  
R H Christenson ◽  
G A Dent ◽  
A Tuszynski
Keyword(s):  
Vitamin B12 ◽  
Serum Vitamin ◽  
Hemoglobin Concentration ◽  
Reference Interval ◽  
Reference Intervals ◽  
The Other ◽  
Mean Values ◽  
Folate Status ◽  
Standard Curve ◽  
Low Concentrations

Abstract For 154 subjects, we verified that vitamin B12 and folate status was normal, using as criteria the average polymorphonuclear lobe count, mean corpuscular volume, and hemoglobin concentration. We then used blood from these subjects to compare values obtained with two radioassay kits, each designed for simultaneous vitamin B12 and folate determination. Although regression analysis showed reasonable correlation between the folate (r = 0.87) and vitamin B12 (r = 0.94) kits, we observed significant differences in the overall mean values for vitamin B12 (p less than 0.01) and folate (p less than 0.001) as measured with the kits in this population. Radioassay standard-curve data for the folate assays were similar, but these data indicated greater sensitivity at low concentrations for one vitamin B12 kit than the other. Using reference intervals recommended in the kit inserts, we found that the vitamin B12 status for 9% of these subjects would have been misclassified by one kit, 2% by the other.

VITAMIN B12 AND FOLIC ACID VALUES IN PREMATURE INFANTS

PEDIATRICS ◽  
1972 ◽  
Vol 50 (4) ◽  
pp. 584-589
Author(s):  
Ambadas Pathak ◽  
Herman A. Godwin ◽  
Luis M. Prudent
Keyword(s):  
Folic Acid ◽  
Vitamin B12 ◽  
Premature Infants ◽  
Serum Vitamin ◽  
Serum Folate ◽  
Born Infant ◽  
Low Concentrations ◽  
Folate And Vitamin B12 ◽  
Relationship Of ◽  
The Relationship

The relationship of serum vitamin B12 and folic acid was studied in 24 premature infants. In 14 of the 24, low serum vitamin B12 values were found around 40 days of age. Serum folic acid concentrations were less frequently depressed and were usually associated with normal red cell folate values. No correlation between hematocrits and vitamin B12 or folate levels was found. It is suggested that low concentrations of serum folate and vitamin B12 result from low dietary intake coupled with increased demand by the prematurely born infant.

scholarly journals Intra- and interindividual variability of carbohydrate-deficient transferrin, γ-glutamyltransferase, and mean corpuscular volume in teetotalers

1998 ◽  
Vol 44 (10) ◽  
pp. 2120-2125 ◽  
Author(s):  
Anders Helander ◽  
Erling Vabö ◽  
Klas Levin ◽  
Stefan Borg
Keyword(s):  
Mean Corpuscular Volume ◽  
Iron Concentration ◽  
Reference Interval ◽  
Reference Intervals ◽  
Mean Value ◽  
Corpuscular Volume ◽  
Mean Values ◽  
Reference Limit ◽  
Carbohydrate Deficient Transferrin ◽  
The Mean

Abstract Blood samples for determination of the biochemical alcohol markers carbohydrate-deficient transferrin (CDT) in serum, γ-glutamyltransferase (GGT) in serum, and erythrocyte mean corpuscular volume (MCV) were collected once every 1–2 weeks over ∼5 months from 10 female and 4 male teetotalers. Mean values for serum CDT (using the CDTectTM assay) ranged from 9.9 to 29.4 units/L (median, 14.2 units/L), and the highest results were obtained in the women. The mean values for serum GGT ranged from 0.15 to 0.49 μkat/L (median, 0.30 μkat/L, or 18 U/L) except for one woman with a very high mean of 3.07 μkat/L. For MCV, the mean values ranged from 79.5 to 91.5 fL. Two women showed several CDT results above the upper reference limit (mean values, 27.6 and 29.4 units/L, respectively); however, their GGT and MCV values fell within the reference intervals. One of these women exhibited an increased total transferrin concentration (mean value, 5.38 g/L), which was possibly related to the use of oral contraceptives and/or a low serum iron concentration. When the CDTect value was expressed relative to total transferrin, a ratio within the reference interval was observed for this woman but not for the other woman with increased CDTect values. The present study demonstrates a considerable variation between individuals in CDT, GGT, and MCV without drinking any alcohol. The results also show that these baseline values are fairly constant over time within the same individual.

scholarly journals Cobalamin (vitamin B12) and B12 binding proteins in hypereosinophilic syndromes and secondary eosinophilia

Blood ◽  
1984 ◽  
Vol 63 (4) ◽  
pp. 779-783
Author(s):  
J Zittoun ◽  
JP Farcet ◽  
J Marquet ◽  
C Sultan ◽  
R Zittoun
Keyword(s):  
Vitamin B12 ◽  
Binding Proteins ◽  
Binding Capacity ◽  
Hypereosinophilic Syndrome ◽  
Elevated Serum ◽  
Serum Vitamin ◽  
Myeloproliferative Disorders ◽  
The Other ◽  
Intracellular Content ◽  
Eosinophil Counts

Serum cobalamin (vitamin B12) and unsaturated B12 binding capacity (UBBC) have been measured in 24 cases of hypereosinophilia: 16 were cases of hypereosinophilic syndrome (HES) and 8 of secondary eosinophilia. The two groups were similar with respect to absolute eosinophil counts. Serum cobalamin and UBBC were found to be markedly increased in most cases of HES and normal in secondary eosinophilia. This elevation of UBBC was mainly related to the increase of R binders (transcobalamins I and III). The elevated serum cobalamin and R binders in HES were due neither to a higher intracellular content of R binders nor to an increased release of these binders from eosinophils of HES. Pure fractions of eosinophils obtained from HES and secondary eosinophilia did not exhibit any difference in vitamin B12 binders. On the other hand, neutrophil-rich fractions from the same patients showed a higher content of intracellular B12 binding proteins than pure eosinophil fractions, irrespective of the cause of eosinophilia. These findings suggest that the increased serum vitamin B12 and UBBC could reflect an expanded pool of both eosinophils and neutrophils in HES and, thus, provide an additional argument for the inclusion of this syndrome in the group of myeloproliferative disorders.

scholarly journals A robust approach to reference interval estimation and evaluation

1998 ◽  
Vol 44 (3) ◽  
pp. 622-631 ◽  
Author(s):  
Paul S Horn ◽  
Amadeo J Pesce ◽  
Bradley E Copeland
Keyword(s):  
Prediction Interval ◽  
Clinical Chemistry ◽  
Real Data ◽  
Reference Interval ◽  
Reference Intervals ◽  
Small Sample ◽  
The Other ◽  
Robust Estimator ◽  
Sample Sizes ◽  
Robust Approach

Abstract We propose a new methodology for the estimation of reference intervals for data sets with small numbers of observations or for those with substantial numbers of outliers. We propose a prediction interval that uses robust estimates of location and scale. The SAS software can be readily modified to do these calculations. We compared four reference interval procedures (nonparametric, transformed, robust with a nonparametric lower limit, and transformed robust) for sample sizes of 20, 40, 60, 80, 100, and 120 from χ2 distributions of 1, 4, 7, and 10 df. χ2 distributions were chosen because they simulate the skewness of distributions often found in clinical chemistry populations. We used the root mean square error as the measure of performance and used computer simulation to calculate this measure. The robust estimator showed the best performance for small sample sizes. As the sample size increased, the performance values converged. The robust method for calculating upper reference interval values yields reasonable results. In two examples using real data for haptoglobin and glucose, the robust estimator provides slightly smaller upper reference limits than the other procedures. Lastly, the robust estimator was compared with the other procedures in a population where 5% of the values were multiplied by a factor of 5. The reference intervals were calculated with and without outlier detection. In this case, the robust approach consistently yielded upper reference interval values that were closer to those of the true underlying distributions. We propose that robust statistical analysis can be of great use for determinations of reference intervals from limited or possibly unreliable data.

Effects of low concentrations of dietary cobalt on liveweight gains, haematology, serum vitamin B12 and biochemistry of Omani goats

2007 ◽  
Vol 173 (1) ◽  
pp. 131-137 ◽  
Author(s):  
Khalid Al-Habsi ◽  
Eugene H. Johnson ◽  
Isam T. Kadim ◽  
Anandarajah Srikandakumar ◽  
Kanthi Annamalai ◽  
...  
Keyword(s):  
Vitamin B12 ◽  
Serum Vitamin ◽  
Low Concentrations

Serum vitamin B12 and folate status in patients with inflammatory bowel diseases

2010 ◽  
Vol 21 (4) ◽  
pp. 320-323 ◽  
Author(s):  
Mustafa Yakut ◽  
Yusuf Üstün ◽  
Gökhan Kabaçam ◽  
Irfan Soykan
Keyword(s):  
Vitamin B12 ◽  
Inflammatory Bowel Diseases ◽  
Serum Vitamin ◽  
Folate Status ◽  
Bowel Diseases ◽  
Inflammatory Bowel

The influence of serum vitamin B12 and folate status on cognitive functioning in very old age

2001 ◽  
Vol 56 (3) ◽  
pp. 247-265 ◽  
Author(s):  
Tarja-Brita Robins Wahlin ◽  
Åke Wahlin ◽  
Bengt Winblad ◽  
Lars Bäckman
Keyword(s):  
Vitamin B12 ◽  
Cognitive Functioning ◽  
Old Age ◽  
Serum Vitamin ◽  
Very Old ◽  
Folate Status ◽  
Very Old Age

Reference intervals for serum total vitamin B12 and holotranscobalamin concentrations and their change points with methylmalonic acid concentration to assess vitamin B12 status during early and mid-pregnancy

2019 ◽  
Vol 57 (11) ◽  
pp. 1790-1798 ◽  
Author(s):  
Theresa H. Schroder ◽  
Amy Tan ◽  
Andre Mattman ◽  
Graham Sinclair ◽  
Susan I. Barr ◽  
...  
Keyword(s):  
Vitamin B12 ◽  
Pregnant Women ◽  
Change Point ◽  
Methylmalonic Acid ◽  
Reference Interval ◽  
Reference Intervals ◽  
Change Points ◽  
Change Point Analysis ◽  
Future Research ◽  
Linear Relationships

Abstract Background Maternal vitamin B12 (B-12) adequacy is important for maternal health and optimal fetal growth. However, pregnancy-specific cut-offs for B-12 biomarkers are lacking. Methods Reference intervals for serum total B-12, holotranscobalamin (holoTC) and methylmalonic acid (MMA) concentrations were calculated following CLSI EP28-A3c guidelines in 723 pregnant women of European (50%) and South Asian (50%) ethnicity, residing in British Columbia, Canada, at median (range) 11.4 (8.3–13.9) and 16.1 (14.9–20.9) weeks of gestation. Change point analyses described relationships between log serum MMA concentration with serum total B-12 and holoTC concentrations, assuming linear-linear relationships. Results The central 95% reference interval limits indicated that serum total B-12 <89.9 and <84.0 pmol/L, holoTC <29.5 and <26.0 pmol/L and MMA >371 and >374 nmol/L, in the first and second trimesters, respectively, may indicate B-12 deficiency in pregnant women. The lower limits of total B-12 and holoTC and the upper limits of MMA significantly differed by ethnicity in both trimesters. According to the change point analysis, total B-12 <186 and <180 pmol/L and holoTC <62.2 and <67.5 pmol/L in the first and second trimesters, respectively, suggested an increased probability of impaired intracellular B-12 status, with no difference between ethnicities. Conclusions We present novel reference limits and change points for B-12 biomarkers, which may be employed to identify possible B-12 deficiency in women during early and mid-pregnancy. Future research is needed to validate these cut-offs and determine the predictors and functional outcomes associated with impaired B-12 status in ethnically diverse populations.

scholarly journals Free hemoglobin reference intervals detected with hemoglobin-cyanide method on a biochemical automatic analyzer ILAB 300 PLUS

2019 ◽  
Vol 4 (3) ◽  
pp. 4-7
Author(s):  
Olga I. Murygina ◽  
Elena R. Zhukova ◽  
Olga V. Petrova ◽  
Dina M. Nikulina
Keyword(s):  
Blood Serum ◽  
Reference Group ◽  
Hemoglobin Concentration ◽  
Reference Interval ◽  
Reference Intervals ◽  
Free Hemoglobin ◽  
Men And Women ◽  
Automatic Analyzer ◽  
Standard Procedures ◽  
Gender And Age

Objectives - to evaluate the reference intervals for free hemoglobin concentration with the help of hemoglobin-cyanide method and a biochemical automatic analyzer. Material and methods. The reference group consisted of 120 healthy men and 120 healthy women from the Astrakhan region aged from 20 to 60 years. The fulfilment of standard procedures during the pre-analytical prelaboratory, pre-analytical laboratory, analytical and post-analytical stages of the study ensured the quality control for free hemoglobin evaluation. Blood samples were taken with cubital vein puncture after applying a tourniquet (for not more than 1 minute), patient in lying position, using two-component blood sampling systems - disposable polypropylene tubes with a blood coagulation activator (Sarstedt, Germany). To obtain blood serum, blood tubes were centrifuged at 2500 rpm during 10 minutes. The free hemoglobin in blood serum was detected by the hemoglobin-cyanide method using a ILAB 300 PLUS biochemical automatic analyzer (Laboratory Instrumentation, USA). The data was processed using the software package Statistica 6.0 for Windows (StatSoft Inc, США). Results. We used the classical approach and followed the strict inclusion and exclusion criteria, recommended by CLSI C 28-A3 guidelines. Gender and age differences in the content of free hemoglobin in blood serum in men and women of the Astrakhan region were not found. The reference interval of free hemoglobin in men and women of the Astrakhan region was evaluated as 0.02-0.84 g/l.

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