Oral cobalamin for pernicious anemia: back from the verge of extinction

Vitamin B12 deficiency

Of the water-soluble vitamins, vitamin B12 (B12) has the lowest daily requirement. It also has several unique properties including a complex pathway for its absorption and assimilation requiring intact gastric and terminal small intestinal function, an enterohepatic pathway, and several dedicated binding proteins and chaperons. The many causes of B12 deficiency include malabsorption and defects in cellular delivery and uptake, as well as limited dietary intake. B12 is required as a cofactor for only two reactions in humans, the cytosolic methionine synthase reaction and the mitochondrial methymalonyl CoA mutase reaction. Disruption of either of these reactions gives rise to B12 deficiency. Although more common with advancing age, because of the higher prevalence of malabsorptive disorders in the elderly, B12 deficiency is widely distributed across all age groups particularly where food insecurity occurs. The consequences and severity of B12 deficiency are variable depending on the degree of deficiency and its duration. Major organ systems affected include the blood, bone marrow and nervous system. Megaloblastic anemia results from a defect in thymidine and therefore DNA synthesis in rapidly dividing cells. Nervous system involvement is varied, some of which results from defective myelin synthesis and repair. Cognitive impairment and psychosis may also occur. Diagnosis of B12 deficiency rests on clinical suspicion followed by laboratory testing, which consists of a panel of tests, that together provide clinically reliable predictive indices. B12 metabolism and deficiency is closely intertwined with folate, another B-vitamin. This chapter explores the various aspects of a unique and fascinating micronutrient.

Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency

BACKGROUND

Vitamin B₁₂ deficiency is common, and the incidence increases with age. Most people with vitamin B₁₂ deficiency are treated in primary care with intramuscular (IM) vitamin B₁₂. Doctors may not be prescribing oral vitamin B₁₂ formulations because they may be unaware of this option or have concerns regarding its effectiveness.

OBJECTIVES

To assess the effects of oral vitamin B₁₂ versus intramuscular vitamin B₁₂ for vitamin B₁₂ deficiency.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and LILACS, as well as the WHO ICTRP and ClinicalTrials.gov. The latest search date was 17 July 2017. We applied no language restrictions. We also contacted authors of relevant trials to enquire about other published or unpublished studies and ongoing trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the effect of oral versus IM vitamin B₁₂ for vitamin B₁₂ deficiency.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were serum vitamin B₁₂ levels, clinical signs and symptoms of vitamin B₁₂ deficiency, and adverse events. Secondary outcomes were health-related quality of life, acceptability to patients, haemoglobin and mean corpuscular volume, total homocysteine and serum methylmalonic acid levels, and socioeconomic effects. We used GRADE to assess the quality of the evidence for important outcomes. We did not perform meta-analyses due to the small number of included trials and substantial clinical heterogeneity.

MAIN RESULTS

Three RCTs met our inclusion criteria. The trials randomised 153 participants (74 participants to oral vitamin B₁₂ and 79 participants to IM vitamin B₁₂). Treatment duration and follow-up ranged between three and four months. The mean age of participants ranged from 38.6 to 72 years. The treatment frequency and daily dose of vitamin B₁₂ in the oral and IM groups varied among trials. Only one trial had low or unclear risk of bias across all domains and outcome measures. Two trials reported data for serum vitamin B₁₂ levels. The overall quality of evidence for this outcome was low due to serious imprecision (low number of trials and participants). In two trials employing 1000 μg/day oral vitamin B₁₂, there was no clinically relevant difference in vitamin B₁₂ levels when compared with IM vitamin B₁₂. One trial used 2000 μg/day vitamin B₁₂ and demonstrated a mean difference of 680 pg/mL (95% confidence interval 392.7 to 967.3) in favour of oral vitamin B₁₂. Two trials reported data on adverse events (very low-quality evidence due to risk of performance bias, detection bias, and serious imprecision). One trial stated that no treatment-related adverse events were seen in both the oral and IM vitamin B₁₂ groups. One trial reported that 2 of 30 participants (6.7%) in the oral vitamin B₁₂ group left the trial early due to adverse events. Orally taken vitamin B₁₂ showed lower treatment-associated costs than IM vitamin B₁₂ in one trial (low-quality evidence due to serious imprecision). No trial reported on clinical signs and symptoms of vitamin B₁₂ deficiency, health-related quality of life, or acceptability of the treatment scheme.

AUTHORS' CONCLUSIONS

Low quality evidence shows oral and IM vitamin B₁₂ having similar effects in terms of normalising serum vitamin B₁₂ levels, but oral treatment costs less. We found very low-quality evidence that oral vitamin B₁₂ appears as safe as IM vitamin B₁₂. Further trials should conduct better randomisation and blinding procedures, recruit more participants, and provide adequate reporting. Future trials should also measure important outcomes such as the clinical signs and symptoms of vitamin B₁₂ deficiency, health related-quality of life, socioeconomic effects, and report adverse events adequately, preferably in a primary care setting.

Oral Vitamin B12 Replacement for the Treatment of Pernicious Anemia

Many patients with pernicious anemia are treated with lifelong intramuscular (IM) vitamin B12 replacement. As early as the 1950s, there were studies suggesting that oral vitamin B12 replacement may provide adequate absorption. Nevertheless, oral vitamin B12 replacement in patients with pernicious anemia remains uncommon in clinical practice. The objective of this review is to provide an update on the effectiveness of oral vitamin B12 for the treatment of pernicious anemia, the recommended dosage, and the required frequency of laboratory test and clinical monitoring. Relevant articles were identified by PubMed search from January 1, 1980 to March 31, 2016 and through hand search of relevant reference articles. Two randomized controlled trials, three prospective papers, one systematic review, and three clinical reviews fulfilled our inclusion criteria. We found that oral vitamin B12 replacement at 1000 μg daily was adequate to replace vitamin B12 levels in patients with pernicious anemia. We conclude that oral vitamin B12 is an effective alternative to vitamin B12 IM injections. Patients should be offered this alternative after an informed discussion on the advantages and disadvantages of both treatment options.

Pernicious anemia. From past to present

Pernicious anemia is currently the most common cause of vitamin B12 deficiency in Western countries. The histological lesion upon which this condition is based is autoimmune chronic atrophic gastritis. The destruction of parietal cells causes a deficiency in intrinsic factor, an essential protein for vitamin B12 absorption in the terminal ileum. Advances in the last two decades have reopened the debate on a disease that seemed to have been forgotten due to its apparent simplicity. The new role of H. pylori, the value of parietal cell antibodies and intrinsic factor antibodies, the true usefulness of serum vitamin B12 levels, the risk of adenocarcinoma and gastric carcinoids and oral vitamin B12 treatment are just some of the current issues analyzed in depth in this review.

Oral vitamin B12 replacement: an effective treatment for vitamin B12 deficiency after total gastrectomy in gastric cancer patients

BACKGROUND

Vitamin B12 deficiency is a common long-term sequelae after total gastrectomy. Intramuscular injection of vitamin B12 is the only known treatment. We investigated the efficacy and safety of oral vitamin B12 replacement for gastric cancer patients with vitamin B12 deficiency after total gastrectomy.

METHODS

We performed a single-arm, open-label, fixed-drug dosage, prospective study (NCT00699478) involving gastric cancer patients who underwent total gastrectomy. Vitamin B12-deficient (<200 pg/ml) patients (n = 30) received daily oral vitamin B12 (dosage: 1500 μg mecobalamin) administration for 3 months. The primary outcome measurement was serum vitamin B12. The secondary outcome measurements were improvement of neurologic symptoms and hematologic findings (serum folate, homocysteine, ferritin, iron, total iron binding capacity, transferrin, and mean corpuscular volume). For comparison, another group of vitamin B12 deficient patients (n = 30) received intramuscular vitamin B12 injections (dosage: 1000 μg cyanocobalamin) weekly for 5 weeks and monthly thereafter for a total of 3 months in a separate study period.

RESULTS

In both groups, mean serum vitamin B12 increased after 30 days of treatment and was maintained up to 90 days. No adverse effects related to oral or intramuscular vitamin B12 replacements were noted. Both groups showed decreased homocysteine levels. Before treatment, 29 patients in the oral vitamin B12 group had neurologic symptoms related to vitamin B12 deficiency. After oral vitamin B12 treatment, 28 patients experienced symptom relief, and 16 patients were symptom free.

CONCLUSIONS

Oral vitamin B12 replacement is an effective and safe treatment for vitamin B12 deficiency in gastric cancer patients after total gastrectomy.

Anemia after bariatric surgery: more than just iron deficiency

Bariatric surgery for morbid obesity is rapidly gaining popularity. Restrictive and/or malabsorptive surgical interventions result in dramatic weight loss with significantly decreased obesity-related morbidity and mortality. Anemia, which may affect as many as two-thirds of these patients, is of concern and generally thought to be caused by iron deficiency. Although iron deficiency in this population may be frequent given pouch hypoacidity, defunctionalized small bowel, and red meat intolerance, it may not account for all anemias seen. First, there is increasing evidence that obesity creates a state of chronic inflammation. Both iron deficiency anemia and anemia of chronic inflammation present with low serum iron levels. Most studies reporting anemia after bariatric surgery lack serum ferritin determinations so that the relative contribution of inflammation to anemia cannot be assessed. Second, a significant number of anemias after bariatric surgery remain unexplained and may be attributable to less frequently seen micronutrient deficiencies such as copper, fatsoluble vitamins A and E, or an imbalance in zinc intake. Third, although deficiencies of folate and vitamin B(12) are infrequent, study observation periods may be too short to detect anemia attributable to vitamin B(12) deficiency because vitamin B(12) storage depletion takes many years. This review is intended to increase awareness of the mechanisms of anemia above and beyond iron deficiency in the bariatric patient and provide healthcare providers with tools for a more thoughtful approach to anemia in this patient population.

Oral cobalamin remains medicine's best kept secret

A cross-sectional survey was conducted in order to describe the use of oral cobalamin among geriatricians, hematologists, and general practitioners, and to explore factors related to its use. The study population consisted of all geriatricians (n = 138) and hematologists (n = 317) listed in the Canadian Medical Directory plus a random sample of 307 general practitioners. The overall response rate was 40%. Intramuscular and oral cobalamin was prescribed by 76 and 32% of the respondents, respectively. Twenty seven percent reported using both oral and intramuscular cobalamin and 6% reported using only oral cobalamin. Only 25% of respondents indicated they were aware of a RCT demonstrating the efficacy of oral cobalamin prior to reading a synopsis of the study in the survey. After multivariate adjustment, only the belief that oral cobalamin was effective and certainty about who carried oral preparations remained independently associated with oral cobalamin use. Oral cobalamin has been shown to be an efficacious, cost efficient and safe method of treating cobalamin deficiency. Nonetheless, it is not used by the majority of physicians treating this condition. Strategies to promote the use of oral cobalamin should be directed at educating physicians of its efficacy and providing them with prescribing information on where it can be purchased.

Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency

BACKGROUND

Vitamin B12 deficiency is common and rises with age. Most people with vitamin B12 deficiency are treated in primary care with intramuscular vitamin B12 which is a considerable source of work for health care professionals. Several case control and case series studies have reported equal efficacy of oral administration of vitamin B12 but it is rarely prescribed in this form, other than in Sweden and Canada. Doctors may not be prescribing oral formulations because they are unaware of this option or have concerns regarding effectiveness.

OBJECTIVES

To assess the effectiveness of oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency.

SEARCH STRATEGY

Searches were undertaken of The Cochrane Library, MEDLINE, EMBASE and Lilacs in early 2005. The bibliographies of all relevant papers identified using this strategy were searched. In addition we contacted authors of relevant identified studies and Vitamin B12 research and pharmaceutical companies to enquire about other published or unpublished studies and ongoing trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) examining the use of oral or intramuscular vitamin B12 to treat vitamin B12 deficiency.

DATA COLLECTION AND ANALYSIS

All abstracts or titles identified by the electronic searches were independently scrutinised by two reviewers. When a difference between reviewers arose, we obtained and reviewed a hard copy of the papers and made decisions by consensus. We obtained a copy of all pre-selected papers and two researchers independently extracted the data from these studies using piloted data extraction forms. The whole group checked whether inclusion and exclusion criteria were met, and disagreement was decided by consensus. The methodological quality of the included studies was independently assessed by two researchers and disagreements were brought back to the whole group and resolved by consensus.

MAIN RESULTS

Two RCT's comparing oral with intramuscular administration of vitamin B12 met our inclusion criteria. The trials recruited a total of 108 participants and followed up 93 of these from 90 days to four months. High oral doses of B12 (1000 mcg and 2000 mcg) were as effective as intramuscular administration in achieving haematological and neurological responses.

AUTHORS' CONCLUSIONS

The evidence derived from these limited studies suggests that 2000 mcg doses of oral vitamin B12 daily and 1000 mcg doses initially daily and thereafter weekly and then monthly may be as effective as intramuscular administration in obtaining short term haematological and neurological responses in vitamin B12 deficient patients.

Medical intelligence in Sweden. Vitamin B12: oral compared with parenteral?

BACKGROUND

Sweden is the only country in which oral high dose vitamin B12 has gained widespread use in the treatment of deficiency states.

OBJECTIVE

The aim of the study was to describe prescribing patterns and sales statistics of vitamin B12 tablets and injections in Sweden 1990-2000.Design, setting, and sources: Official statistics of cobalamin prescriptions and sales were used.

RESULTS

The use of vitamin B12 increased in Sweden 1990-2000, mainly because of an increase in the use of oral high dose vitamin B12 therapy. The experience, in statistical terms a "total investigation", comprised 1,000,000 patient years for tablets and 750,000 patient years for injections. During 2000, 13% of residents aged 70 and over were treated with vitamin B12, two of three with the tablet preparation. Most patients in Sweden requiring vitamin B12 therapy have transferred from parenteral to oral high dose vitamin B12 since 1964, when the oral preparation was introduced.

CONCLUSION

The findings suggest that many patients in other post-industrial societies may also be suitable for oral vitamin B12 treatment.

Oral versus intramuscular cobalamin treatment in megaloblastic anemia: a single-center, prospective, randomized, open-label study

BACKGROUND

Cobalamin (vitamin B12) deficiency, the most common cause of megaloblastic anemia, is treated with intramuscular (IM) cobalamin. It has been suggested by some investigators that oral (p.o.) cobalamin treatment may be as effective in the treatment of this condition, with the advantages of ease of administration and lower cost.

OBJECTIVE

This study assessed the effects and cost of p.o. versus i.m. cobalamin treatment in patients with megaloblastic anemia due to cobalamin deficiency.

METHODS

This was a 90-day, prospective, randomized, open-label study conducted at the Division of Hematology, Department of Internal Medicine, Adnan Menderes University Research and Practice Hospital (Aydin, Turkey). Patients aged > or =16 years with megaloblastic anemia due to cobalamin deficiency were randomized to receive 1000-microg cobalamin p.o. once daily for 10 days (p.o. group) or 1000-microg cobalamin i.m. once daily for 10 days (i.m. group). After 10 days, both treatments were administered once a week for 4 weeks, and after that, once a month for life. Patients were assessed for the presence of reticulocytosis between treatment days 5 and 10 until it was detected. Therapeutic effectiveness was assessed by measuring hematologic parameters on days 0, 10, 30, and 90 and serum vitamin B12 concentration on days 0 and 90. The Mini-Mental State Examination was used before and after the B12 therapy for cognitive function assessment and 125-Hz diapozone was used for vibration threshold testing. Neurologic sensory assessment, including soft-touch and pinprick examinations, was used to identify neuropathy at baseline and study end. Tolerability was assessed using laboratory tests and patient interview. Cost was assessed using the cost of the study drug and of the injection.

RESULTS

Sixty patients completed the study 26 in the p.o. group (16 men, 10 women; mean [SD] age, 60 [15] years) and 34 in the i.m. group (17 men, 17 women; mean [SD] age, 64 [10] years). Reticulocytosis was observed in all patients. In the p.o. group, at days 30 and 90, all hematologic parameters changed significantly versus day 0 (mean hemoglobin levels increased [both P<0.001]; mean corpuscular volume decreased [both P<0.001]; mean white blood cell count increased [day 30, P<0.01; day 90, P<0.001]; and mean platelet count increased [both P<0.001]). The mean serum vitamin B12 concentration increased significantly from day 0 to 90 (P<0.001). These hematologic parameters and the recovery patterns were similar between the 2 groups. Neurologic findings included sensitive peripheral neuropathy in 9 patients (15.0%), alteration of cognitive function (loss of memory, impaired concentration) in 7 patients (11.7%), and loss of sense of vibration in 5 patients (8.3%). Neurologic improvement was detected in 7 of 9 patients (77.8%) in the p.o. group and 9 of 12 patients (75.0%) in the i.m. group at day 30.

CONCLUSIONS

In this study of patients with megaloblastic anemia due to cobalamin deficiency, p.o. cobalamin treatment was as effective as i.m. cobalamin treatment. P.o. treatment also was better tolerated and less expensive compared with IM treatment. However, because of the small sample size and the short term of this study, further long-term studies are needed to determine the efficacy of p.o. cobalamin treatment.

Is low-dose oral cobalamin enough to normalize cobalamin function in older people?

OBJECTIVES

To investigate whether the use of low-dose oral cobalamin (Cbl) supplements by older persons, as frequently found in multivitamin preparations, affects their Cbl serum concentrations and function, determined by measurements of the serum Cbl-related metabolites methylmalonic acid (MMA), homocysteine (HCYS), and methylcitric acid (MCTR).

DESIGN

Cross-sectional study.

SETTING

Community.

PARTICIPANTS

Two hundred forty-two independent, active, community-living, older adult volunteers recruited from community events and activities for seniors.

MEASUREMENTS

We systematically collected data on vitamin supplement intake, diet, medications, and medical and surgical history. Serum was obtained for Cbl, MMA, HCYS, and MCTR, and creatinine and hematological parameters.

RESULTS

Serum levels of Cbl were significantly higher in subjects on oral Cbl supplements (2-37.5 microg/day). Similarly, serum levels of the metabolites MMA, HCYS, and MCTR were also lower in subjects on Cbl supplementation. Intake of low-dose oral supplements of Cbl significantly reduced the odds of low Cbl levels or high MMA. The relationship between Cbl supplement dosage and the biochemical parameters was dose dependent.

CONCLUSION

Oral Cbl (2-37.5 microg/day) intake by community-dwelling healthy older adults is associated with higher serum levels of Cbl and improved or normalized Cbl function, as indicated by lower concentrations of the metabolites MMA, HCYS, and MCTR. Use of low-dose oral Cbl replacement therapy might be sufficient to prevent Cbl deficiency in a large proportion of this population.

Independent effect of vitamin B12 deficiency on hematological status in older Chinese vegetarian women

We have examined the independent effect of vitamin B(12) deficiency on hematological indices in older Chinese vegetarian women using a cross-sectional study design: 119 women older than 55 years who had been vegetarian for more than 3 years were studied. Fasting blood samples were taken for complete blood count, serum iron, total serum iron binding capacity, serum iron saturation, serum vitamin B(12), serum folate, serum methylmalonic acid levels (MMA), and renal function test. Subjects with iron deficiency (iron saturation <15%) and those with serum creatinine >150 mmol/L were excluded. The prevalence of definite vitamin B(12) deficiency (vitamin B(12) level < 150 pmol/L and MMA >or= 0.4 micromol/L) was 42%. Another 32.8% had possible vitamin B(12) deficiency (either criterion). The prevalence of iron deficiency was 10%. After exclusions, 96 subjects were further analyzed. Vitamin B(12) deficiency defined by serum vitamin B(12) and MMA was associated with a decrease in hemoglobin concentrations by up to 0.9 g/dL, but it was not associated with an increase in mean corpuscular volume (MCV). Serum MMA but not vitamin B(12) levels correlated inversely with hemoglobin and platelet counts and positively with MCV, after adjustment of confounding factors. However, the percentage of subjects with anemia did not increase significantly until serum MMA became >1.0 micromol/L. In conclusion, vitamin B(12) deficiency was associated with a significant decrease in hemoglobin concentration. However, anemia associated with vitamin B(12) deficiency was seldom macrocytic. We recommend that older vegetarians should be given vitamin B(12) supplements routinely.

Treatment of vitamin b(12)-deficiency anemia: oral versus parenteral therapy

OBJECTIVE

To evaluate the use of oral cyanocobalamin therapy in the treatment of cobalamin (vitamin B(12))-deficient anemia.

DATA SOURCES

Primary and review articles were identified by MEDLINE search (1966-May 2000) and through secondary sources.

DATA SYNTHESIS

Cobalamin-deficient anemia is among the most common diagnoses in older populations. Cobalamin-deficient anemia may be diagnosed as pernicious anemia, resulting from the lack of intrinsic factor required for cobalamin absorption or as protein malabsorption from the inability to displace cobalamin from protein food sources. Several studies provide evidence that daily oral cyanocobalamin as opposed to monthly parenteral formulations may adequately treat both types of cobalamin-deficient anemias.

CONCLUSIONS

Daily oral cyanocobalamin at doses of 1000-2000 microg can be used for treatment in most cobalamin-deficient patients who can tolerate oral supplementation. There are inadequate data at the present time to support the use of oral cyanocobalamin replacement in patients with severe neurologic involvement.

Vitamin B12 deficiency--need for a new guideline

OBJECTIVES

Many patients with vitamin B12 deficiency do not have anemia or macrocytosis, but the prevalence of B12 deficiency in patients without macrocytosis is not known.

METHODS

We investigated the prevalence of B12 deficiency among patients with normocytosis and microcytosis and recommended a screening strategy. All patients (n = 3714) with serum B12 measured at the Prince of Wales Hospital in 1996 were reviewed. The prevalence of serum B12 less than 140 pmol/L was determined for the following patient subgroups: younger than 70 y, older than 70 y, anemic, non-anemic, macrocytic, normocytic, microcytic, documented iron deficiency, and documented thalassemia.

RESULTS

The prevalence of B12 deficiency (<140 pmol/L) ranged from 4.8% to 9.8% among the different subgroups.

CONCLUSIONS

Whatever screening criteria were used, a significant number of B12-deficient patients will be missed. Therefore, there may be a case for universal vitamin B12 screening.