Vitamin B12 Status in Pregnancy among Immigrants to Britain

Haemoglobin, serum vitamin B₁₂, and serum and red cell folate levels have been measured in 322 pregnant immigrant women in London at their first booking and in a proportion at 34 weeks of gestation and postnatally. The Indian, East-African Indian, and Pakistani and Bangladeshi patients showed significantly lower initial mean serum vitamin B₁₂ levels than the European group, the levels being lower in Hindu and Sikh patients than in Moslems. The patients of West Indian, Indian, and East-African Indian origin showed significantly lower initial mean haemoglobin levels than the immigrants from European countries. Though there was no overall correlation between haemoglobin and serum vitamin B₁₂ level the incidence of hypersegmented polymorphs and macrocytosis in the peripheral blood was highest in the Indian and East-African Indian patients, and both these features were particularly frequent in patients with subnormal serum vitamin B₁₂ levels. Only one patient, however, had overt megaloblastic anaemia due to vitamin B₁₂ deficiency. The Indian patients whose red cell folate levels were less than 200 ng/ml also had a lower mean serum vitamin B₁₂ level than those with red cell folate levels greater than 200 ng/ml. The Indian patients had smaller babies than the Europeans but this was not related to the differences in vitamin B₁₂ status between the two groups. However, out of 39 babies of the Indian group 5 (13%) showed subnormal serum vitamin B₁₂ levels in the first 10 days of life, the lowest level being 120 pg/ml.Though there was an overall statistically significant fall in serum vitamin B₁₂ between first booking and 34 weeks of pregnancy there was no significant fall in serum vitamin B₁₂ in those who initially had subnormal levels. Thus many Indian women are vitamin B₁₂ deficient in pregnancy, and this is associated with morphological blood abnormalities in many cases, but megaloblastic anaemia due to this deficiency is relatively infrequent.     

Vitamin-B12 Status of Patients on Long-term Metformin Therapy

Vitamin-B₁₂ malabsorption has been found in 21 (30%) of 71 diabetic patients taking long-term metformin therapy in addition to dietary management. The patients with evidence of B₁₂ malabsorption had significantly lower haemoglobin levels (and significantly higher serum folic acid levels) than those with normal B₁₂ absorption. Steatorrhoea was found in only one patient. Stopping metformin therapy resulted in reversion of B₁₂ absorption to normal in most patients examined. Four patients with B₁₂ malabsorption were found to have pathologically low serum B₁₂ levels. The causes and implications of these findings are discussed and it is concluded that all patients on long-term metformin therapy should have annual serum B₁₂ estimations.     

The use of serum glial fibrillary acidic protein measurements in the diagnosis of neuromyelitis optica spectrum optic neuritis

Background

Glial fibrillary acidic protein (GFAP) is a specific intermediate filament of the cytoskeleton of the astrocyte and may be used as a specific marker for astrocytic damage. It is detectable in the cerebrospinal fluid following a relapse caused by Multiple Sclerosis (MS) and Neuromyelitis Optica (NMO) spectrum disease. Higher levels are found following an NMO-related relapse. It is not known if GFAP is also detectable in the serum following such relapses. In particular, it is not known if lesions limited to the optic nerve release GFAP in sufficient quantities to be detectable within the serum. The aim of this study was to ascertain the extent to which serum GFAP levels can distinguish between an episode of optic neuritis (ON) related to NMO spectrum disease and ON from other causes.

Methodology/Principal Findings

Out of 150 patients consecutively presenting to our eye hospital over the period March 2009 until July 2010, we were able to collect a serum sample from 12 patients who had presented with MS-related ON and from 10 patients who had presented with NMO spectrum disease-related ON. We also identified 8 patients with recurrent isolated ON and 8 patients with a corticosteroid-dependent optic neuropathy in the absence of any identified aetiology. GFAP was detectable in the serum of all but three patients (two patients with MS-related ON and one with recurrent optic neuritis). The median serum GFAP level in the patient group with NMO spectrum disease was 4.63 pg/mL whereas in all other cases combined together, this was 2.14 pg/mL. The difference was statistically significant (P = 0.01). A similar statistically significant difference was found when cases with pathology limited to the optic nerve were compared (P = 0.03).

Conclusions

Glial pathology in NMO related optic neuritis is reflected in elevated serum GFAP levels independently of whether or not there is extra-optic nerve disease.     

Parallel Changes in Structural and Functional Measures of Optic Nerve Myelination after Optic Neuritis

IntroductionVisual evoked potential (VEP) latency prolongation and optic nerve lesion length after acute optic neuritis (ON) corresponds to the degree of demyelination, while subsequent recovery of latency may represent optic nerve remyelination. We aimed to investigate the relationship between multifocal VEP (mfVEP) latency and optic nerve lesion length after acute ON.MethodsThirty acute ON patients were studied at 1,3,6 and 12 months using mfVEP and at 1 and 12 months with optic nerve MRI. LogMAR and low contrast visual acuity were documented. By one month, the mfVEP amplitude had recovered sufficiently for latency to be measured in 23 (76.7%) patients with seven patients having no recordable mfVEP in more than 66% of segments in at least one test. Only data from these 23 patients was analysed further.ResultsBoth latency and lesion length showed significant recovery during the follow-up period. Lesion length and mfVEP latency were highly correlated at 1 (r = 0.94, p = <0.0001) and 12 months (r = 0.75, p < 0.001). Both measures demonstrated a similar trend of recovery. Speed of latency recovery was faster in the early follow-up period while lesion length shortening remained relatively constant. At 1 month, latency delay was worse by 1.76ms for additional 1mm of lesion length while at 12 months, 1mm of lesion length accounted for 1.94ms of latency delay.ConclusionA strong association between two putative measures of demyelination in early and chronic ON was found. Parallel recovery of both measures could reflect optic nerve remyelination.     

Impact of Helicobacter pylori on the development of vitamin B12 deficiency in the absence of gastric atrophy

Background. Cobalamin (vitamin B₁₂) deficiency is associated with Helicobacter pylori infection. This study examined how serum vitamin B₁₂ levels relate to gastric mucosa H. pylori density and histology, and to hematological findings in patients with minimal or no gastric atrophy. A second aim was to confirm that H. pylori eradication therapy increases serum B₁₂. Materials and Methods. Biopsies of the gastric mucosa from a population of dyspeptic patients were graded for level of chronic inflammation, neutrophil activity, atrophy, and H. pylori density. A total of 145 H. pylori‐infected patients with minimal or no atrophy were included in the study. Serum cobalamin level, hemoglobin level, and mean corpuscular volume were measured in the 145 patients before eradication therapy, and in 65 of the subjects after treatment. The hematologic findings before and after eradication therapy and correlations between serum vitamin B₁₂ level and histologic parameters, hematologic findings, and patient age were statistically analyzed. Results. There was no significant correlation between serum cobalamin level and patient age. Before treatment all the histopathological scores were inversely correlated with serum vitamin B₁₂ level (p < .01) on univariate analysis. Only H. pylori density was significantly associated with B₁₂ level on multivariate analysis. Serum hemoglobin and cobalamin levels were significantly increased after treatment, regardless of H. pylori eradication status (p < .001). Conclusion. The findings provide strong evidence that H. pylori infection is associated with cobalamin deficiency, and show that this is true even in patients with nonulcer dyspepsia and minimal or no gastric atrophy.     

Vitamin B12 Excretion in Patients with Various Skin Diseases

The excretion in the urine of ⁵⁸Co after an oral dose of ⁵⁸Co vitamin B₁₂ given together with intrinsic factor has been found to be reduced in a number of patients with psoriasis, eczema, and other less common dermatoses. There is a correlation between the abnormality and the extent of the rash. A reduced glomerular filtration rate was found in a few of the patients in whom it was measured, and this must have been responsible, at least in part, for the reduced excretion of vitamin B₁₂ in these patients, but abnormal vitamin B₁₂ excretion also occurred in the absence of impaired renal function. Our evidence is insufficient to show whether malabsorption or increased tissue utilization of vitamin B₁₂ was the explanation in other cases. Certainly a number of patients had steatorrhoea, and in these it is most likely that malabsorption was the major factor. In patients without steatorrhoea a lone malabsorption of vitamin B₁₂ cannot be excluded. A decreased serum concentration of vitamin B₁₂ was found in only one of the patients.     

Assessment of Deoxyuridine Suppression Test in Diagnosis of Vitamin B12 or Folate Deficiency

Deoxyuridine (dU) suppression tests have been performed on virtually all marrow samples aspirated at this hospital over the past 12 months. Of the 110 samples studied 26 gave abnormal results, and these 26 samples came from patients deficient in either vitamin B₁₂ or folate. The dU suppression test was found to be of particular value in the diagnosis of vitamin B₁₂ or folate deficiency in non-anaemic patients with macrocytosis and equivocal changes in marrow morphology and in patients in whom the serum vitamin B₁₂ or red cell folate levels were within the normal range.     

Correlation of Serum and Urine Vitamin B12

The relation between the serum vitamin B₁₂ level and the daily loss of vitamin B₁₂ in urine was examined in patients with normal serum vitamin B₁₂ levels and in patients suffering from vitamin B₁₂ deficiency. A linear correlation was found between the two measurements, suggesting that the serum vitamin B₁₂ level is a governing factor in the urinary loss of vitamin B₁₂. The contribution by this loss to the total loss of vitamin B₁₂ from the body is small under normal circumstances but becomes quantitatively more important with the depletion of body stores.     

Serum Folate and Vitamine B12 Levels in Acute and Chronic Renal Disease. Effect of Peritoneal Dialysis

Serum folate and vitamin B₁₂ levels have been measured in 32 patients with renal failure. The initial mean serum folate level was raised above normal in seven patients with acute renal failure whereas the mean level in eight patients severely ill from chronic renal failure was significantly lower than normal. Serum folate levels fell during peritoneal dialysis and rose between dialyses in all these patients and also in one patient who was dialysed for acute pancreatitis.The mean serum B₁₂ level was raised in patients with both acute and chronic renal failure, but there was no consistent change in serum B₁₂ level during dialysis.Hypersegmented polymorphs were present in the peripheral blood film of most of the patients with acute or chronic renal failure. Their presence bore no relation to the clinical state, blood urea, serum folate, or serum B₁₂ level of the patients.     

Free and Total Vitamin B12 in Cerebrospinal Fluid

Free and total vitamin B₁₂ levels in serum and cerebrospinal fluid (CSF) were bioassayed, since there were no available data on the relationship between free and total vitamin B₁₂ in CSF or between free vitamin in serum and CSF vitamin B₁₂. The subjects were 43 neurological patients. Serum levels were normal in 40 of 43 patients. Values for free and total vitamin B₁₂ in CSF were the same in 42 of 43 patients. Mean CSF vitamin B₁₂ was 21 μμg./ml. In 17 cases CSF vitamin B₁₂ equalled free vitamin B₁₂ level in serum, in 16 cases CSF vitamin B₁₂ was lower than the free level in serum, and in 10 cases CSF vitamin B₁₂ was higher than the free vitamin level in serum. There was no apparent diagnostic correlation. The findings suggest that vitamin B₁₂ is not bound in CSF and that there is some selective control of passage of vitamin B₁₂ across the blood-CSF barrier.     

The appearance of pars planitis in multiple sclerosis

The aim of the study was to investigate the clinical association of multiple sclerosis and pars planitis (or intermediate uveitis), as well as to determine the incidence of pars planitis in multiple sclerosis patients. During the period of one year authors examined 42 patients with multiple sclerosis divided into two groups. First group consisted of 23 patients with history of optic neuritis and the second group consisted of 19 patients who have never had optic neuritis. The mean age of patients in the first group was 31.7 +/- 5.1 years and in the second group 29.1 +/- 8.1 years. Pars planitis was found in 12 patients with multiple sclerosis. Age, sex and degree of neurological disability had no influence on the appearance of pars planitis. Although optic neuritis is considered to be the most common ocular manifestation of multiple sclerosis, the significant number of patients with multiple sclerosis has pars planitis.     

Selective vitamin B12 malabsorption in two siblings

Two siblings with megaloblastic anemia responsive to parenteral vitamin B₁₂ were studied to elucidate the cause of the B₁₂ deficiency. Gastric juice from both contained acid and functional intrinsic factor. Serum contained transcobalamin II and lacked antibodies to intrinsic factor. Schilling tests showed vitamin B₁₂ malabsorption uncorrected by hog intrinsic factor or pancreatic extract. Other parameters of small intestinal function were normal. Proteinuria was initially present in both but cleared in one following treatment with B₁₂. These patients with “familial selective vitamin B₁₂ malabsorption” are the first reported from Canada. Only 37 cases have been reported in the world literature to date.     

Lesion Activity on Brain MRI in a Chinese Population with Unilateral Optic Neuritis

Longitudinal studies have shown that brain white matter lesions are strong predictors of the conversion of unilateral optic neuritis to multiple sclerosis (MS) in Caucasian populations. Consequently brain MRI criteria have been developed to improve the prediction of the development of clinically definite multiple sclerosis (CDMS). In Asian populations, optic neuritis may be the first sign of classical or optic-spinal MS. These signs add to the uncertainty regarding brain MRI changes with respect to the course of unilateral optic neuritis. The aim of this study was to examine the association between brain lesion activity and conversion to CDMS in Chinese patients with unilateral optic neuritis. A small prospective cohort study of 40 consecutive Chinese patients who presented with unilateral optic neuritis was conducted. Brain lesion activity was recorded as the incidence of Gd-enhanced lesions and new T2 lesions. Brain lesions on MRI that were characteristic of MS were defined according to the 2010 revisions of the McDonald criteria. The primary endpoint was the development of CDMS. We found that nineteen patients (48%) had brain lesions that were characteristic of MS on the initial scan. One of these patients (3%) had Gd-enhanced brain lesions. A significantly lower percentage of the patients (10%, p<0.001) presented with new T2 brain lesions on the second scan. During a median of 5 years of follow-up, seven patients (18%) developed CDMS. There was no significant difference in the conversion rate to CDMS between patients with and without brain lesions that were characteristic of MS (4/19 and 3/21, respectively; Fisher exact test, one-sided, p = 0.44). We conclude that brain lesions characteristic of MS are common in Chinese patients with unilateral optic neuritis; however, these patients exhibit low lesion activity. The predictive value of brain lesion activity for CDMS requires investigation in additional patients.     

Malabsorption of Vitamin B12 in Diabetic Patients Treated with Phenformin: A Comparison with Metformin

An investigation into B₁₂ absorption in diabetic patients on long-term phenformin therapy was undertaken and the results were compared to a similar investigation previously reported in diabetics on long-term metformin. Forty-six per cent of patients were found to have B₁₂ malabsorption as shown by abnormal results of Schilling tests.The mechanism of B₁₂ malabsorption is unknown but it is suggested that all patients on long-term phenformin therapy should, like the patients on metformin, have annual serum B₁₂ estimations until the results of a longer follow-up series are known.     

Vitamin B12 Content of Circulating Leukocytes as an Aid in the Differentiation of the Acute Leukemias

From 25 patients with acute leukemia 116 specimens of leukocytes were assayed microbiologically for total vitamin B₁₂ to determine if variation in vitamin B₁₂ content would help in differentiating the acute leukemias. The mean cell vitamin B₁₂ levels (μμg./10⁸ cells) in the different types of leukemia were: lymphoblastic 464, myeloblastic 1058 and monocytic 200. Cell vitamin B₁₂ levels above the normal range (100-800 μμg./10⁸ cells) are suggestive of myeloblastic leukemia. The only elevated cell vitamin B₁₂ levels comparable to those found in myeloblastic leukemia were in reticulum cell leukemia, and this type of leukemia was not difficult to diagnose morphologically. Blast cells contained more vitamin B₁₂ than mature cells of the same series; there was a significant positive correlation between the percentage of blast cells and cell levels of total vitamin B₁₂ in both lymphoblastic and myeloblastic leukemia.     

Use of pattern electroretinography to differentiate acute optic neuritis from acute anterior ischemic optic neuropathy

The transient pattern electroretinogram (PERG) was recorded from 16 patients with acute neuritis and from 13 patients with acute non-arteritic ischemic optic neuropathy (AION). All patients were tested within 35 days from the the onset of visual symptoms and all had significant central visual field abnormalities in their affected eyes as quantified by automated perimetry. Analysis of the PERGs showed that the amplitude of the N95 peak was abnormally reduced for each eye affected with AION while it remained normal in optic neuritis. No significant alteration in P50 amplitude was observed in either condition. The loss of N95 amplitude in AION was highly correlated with the average depth of visual field loss (in decibels) within a radius of 10° of fixation. These results suggest that PERG could be used early in the course of optic neuropathy to distinguish optic neuritis from AION in those cases for which the diagnosis is still uncertain after the clinical examination.     

Polymorphism of vitamin B12 [57Col binding proteins in rabbit serum

When rabbit serum labelled with vitamin B₁₂[⁵⁷Co] was subjected to starch gel electrophoresis and au;oradiography, three phenotypes of proteins capable of binding vitamin B₁₂ were observed. Family data revealed that these phenotypes (called TC-A, TC-AB and TC-B) are controlied by two codominant alleles (TC^A and TC^B), at an autosomic locus. Proteins capable of binding vitamin B₁₂ both in vivo and in vitro are commonly referred to as Transcobalamins and can be found in the serum of numerous animal species (for a review, see Glass, 1974; Allen, 1975; Stenman, 1975). Furthermore, Daiger et al. (1975a) have described seven different patterns of vitamin B₁₂ binding proteins which occur in human plasma and which are presumably controlled by four alleles. The present paper describes experiments in which both starch gel electrophoresis and autoradiography are used to identify three phenotypes of rabbit serum proteins responsible for binding vitamin B₁₂ in vitro. It was found that these three phenotypes are controlled by two allelic codominant genes, at an autosomic locus. Individual serum samples (30 μl), obtained from 385 White New Zealand rabbits varying in age from one month to three years, were incubated with 0.1 ng of vitamin B₁₂[⁵⁷Co] (specific activity: 180 μCi/μg; Lot 247; Radiochemical Centre, Amersham, England) at 37°C for 30 minutes. Starch gel electrophoresis and autoradiography were performed as described by Geldermann (1970) and Daiger et al. (1975b), respectively. Electrofocusing (pH range 3.5–9.5) was conducted in the 2117 Multiphor apparatus (LKB, Bromma, Sweden) according to the manufacturer's instructions. The resulting pH gradient was measured with a surface pH electrode (Ingold, Zürich, Switzerland).     

Smoking in Pregnancy and Vitamin B12 Metabolism

In pregnancy the level of serum vitamin B₁₂ is lower in women who smoke than in non-smokers. This finding occurs independently of social class, parity, or level of haemoglobin. In addition, the mean serum B₁₂ level tends to be less in women who are anaemic and is less in those women who have smaller babies. These findings may be an effect of the cyanide content of tobacco smoke, since cyanide may be detoxified by a mechanism which depletes the stores of vitamin B₁₂ in the body.     

Vitamin B12, homocysteine and carotid plaque in the era of folic acid fortification of enriched cereal grain products

Background

Carotid plaque area is a strong predictor of cardiovascular events. High homocysteine levels, which are associated with plaque formation, can result from inadequate intake of folate and vitamin B₁₂. Now that folic acid fortification is widespread in North America, vitamin B₁₂ has become an important determinant of homocysteine levels. We sought to determine the prevalence of low serum levels of vitamin B₁₂, and their relation to homocysteine levels and carotid plaque area among patients referred for treatment of vascular disease since folic acid fortification of enriched grain products.

Methods

We evaluated 421 consecutive new patients with complete data whom we saw in our vascular disease prevention clinics between January 1998 and January 2002. We measured total carotid plaque area by ultrasound and determined homocysteine and serum vitamin B₁₂ levels in all patients.

Results

The patients, 215 men and 206 women, ranged in age from 37 to 90 years (mean 66 years). Most were taking medications for hypertension (67%) and dyslipidemia (62%). Seventy-three patients (17%) had vitamin B₁₂ deficiency (vitamin B₁₂ level < 258 pmol/L with homocysteine level > 14 μmol/L or methylmalonic acid level > 271 nmol/L). The mean area of carotid plaque was significantly larger among the group of patients whose vitamin B₁₂ level was below the median of 253 pmol/L than among those whose vitamin B₁₂ level was above the median: 1.36 (standard deviation [SD] 1.27) cm² v. 1.09 (SD 1.0) cm²; p = 0.016.

Conclusions

Vitamin B₁₂ deficiency is surprisingly common among patients with vascular disease, and, in the setting of folic acid fortification, low serum vitamin B₁₂ levels are a major determinant of elevated homocysteine levels and increased carotid plaque area.Elevated plasma total homocysteine levels are a strong, graded independent risk factor for stroke and myocardial infarction.^1,2 Mechanisms by which homocysteine may cause vascular disease include a propensity for thrombosis and impaired thrombolysis, increased production of hydrogen peroxide, endothelial dysfunction and increased oxidation of low-density lipoproteins and Lp(a) lipoproteins.³ Folic acid fortification of enriched cereal grain products began in North America in March 1996 and was made mandatory in 1998. Fortification has reduced the number of neural tube defects by half,⁴ which is clearly a beneficial outcome, but so far it has had little impact on cardiovascular mortality.⁵Carotid plaque area is a strong predictor of cardiovascular events.⁶ High homocysteine levels, which are associated with plaque formation, can result from inadequate intake of folate and vitamin B₁₂. Now that folic acid fortification is widespread, vitamin B₁₂ has become an important determinant of homocysteine levels.⁷ We sought to determine the prevalence of low serum levels of vitamin B₁₂, and their relation to homocysteine levels and carotid plaque area among patients referred for treatment of vascular disease since folic acid fortification of enriched grain products.     

GROWTH OF VITAMIN B12-LIMITED CULTURES: THALASSIOSIRA PSEUDONANA,MONOCHRYSIS LUTHERI,AND ISOCHRYSIS GALBANA1,2

The growth rates of 3 species of phytoplankton were found to be dependent on the vitamin B₁₂ concentrations in the media. In batch cultures, the vitamin B₁₂ half-saturation constants and standard errors were 0.39 ± 0.042 μμg/ml for Thalassiosira pseudonana (clone 3H), 1.69 ± 0.24 μμg/ml for Isochrysis galbana, and 2.77 ± 1.65 μμg/ml for Monochrysis lutheri. A chemostat was used to grow T. pseudonana with vitamin B₁₂ as the controlling factor. In the chemostat the yield and standard deviation, 102 ± 21 × 10⁴ cells/μμg vitamin B₁₂, was the same as in the batch culture, 126 ± 13 ± 10⁴ cells/μμg. The chemostat half-saturation constant, 0.26 ± 0.068 μμg/ml vitamin B₁₂, and maximum growth rate were in agreement with those obtained in batch cultures. Vitamin concentrations for maximum growth, rates were greater than those calculated necessary from yield data to give observed population densities similar to those in natural waters. In the sea the effect of vitamin B₁₂ concentration on growth rates may be complicated by low concentrations of other nutrients or the presence of inhibitors.