[Vitamin B12 in practice: When to test ? How to test ? And who should be treated?] / Vitamine B12 en pratique : quand tester ? Comment tester ? Et qui substituer ?

Vitamin B12 deficiency is common in outpatients and inpatient populations, with potentially severe neuropsychiatric and hematological impact, which requires timely diagnosis and treatment. The different diagnostic tests all have their limitations but can be combined, sequentially. We propose to review the treatment options according to the different etiologies of the deficiency, highlighting the costs of the therapies and their coverage by the health insurance.

La carence en vitamine B12 est fréquente en médecine ambulatoire et hospitalière, avec des conséquences neuropsychiatriques et hématologiques potentiellement sévères, nécessitant un diagnostic et un traitement adéquat. Les différents tests diagnostiques ont tous leurs limitations mais peuvent être utilisés de manière complémentaire. Nous proposons de refaire un point sur les possibilités de traitement en fonction des différentes étiologies de la carence, en mettant notamment en exergue les différents coûts des thérapies et leur prise en charge par l'assurance de base.

Assessment of Reference Range of Serum Homocysteine from the Post-therapy Values of Cobalamin and Folate Deficiency Patients.

OBJECTIVES: Ideally, the upper reference limit of plasma or serum homocysteine (Hcy) is to be defined from the studies done on individuals with normal cobalamin and folate status. It is difficult to separate the truly healthy (Cobalamin/Folate Replete) individuals from the randomly selected, apparently healthy individuals who are sub-clinically deficient of cobalamin/folate. The present study was aimed at defining the reference values for the serum homocysteine from individuals with normalized cobalamin and folate status. METHODS: In our study, 215 patients with cobalamin, folic acid deficiency were treated accordingly till complete restoration of clinical and laboratory abnormalities. The post-therapy serum Hcy values were used as reference values. RESULTS: Post-therapy serum Hcy values 12.56 µmol/L (95th percentile), 11.4 µmol/L (85th percentile), 9.8 µmol/L (67th percentile) were seen. The hyperhomocysteinemia was more visible (17.3% gain in prevalence) in the same patient group if interpreted using the post-therapy Hcy value (11.4 µmol/L) as the cut-off. There was no difference between the genders and age groups in the pre or post-therapy Hcy values. CONCLUSIONS: The benefit of the gain in prevalence of disease or the increase in the sensitivity of the test, though small, gets magnified in common diseases and in populous countries. Selection of the individuals is as important as the method or the reagent used in the method when a particular parameter is studied. Repleting the vitamin stores in the confirmed vitamin-deficient patients is more appropriate and easily feasible, since anyway they require treatment, than doing the same on the apparently healthy people. The data thus obtained can be better used as the reference value, for a more meaningful interpretation. The reference range can in turn be used to identify the sub-clinically deficient but asymptomatic people and managed accordingly.

Characteristics of patients with vitamin B12-responsive neuropathy: a case series with systematic repeated electrophysiological assessment.

BACKGROUND: Vitamin B12 (B12) has a fundamental role in both central and peripheral nervous system function at all ages. Neurologic manifestations may be the earliest and often the only manifestation of B12 deficiency. Mostly because of the poor sensitivity of methods of determination for B12 levels, peripheral neuropathy remains a classical but underdiagnosed complication of B12 deficiency. So the clinical and electrophysiological characteristics of B12-responsive neuropathy are not well known. METHODS: A retrospective study of patients with B12-responsive neuropathy was conducted at our hospital on a 3-year period. The criteria for inclusion were: (a) neuropathy confirmed by the electrophysiological study (nerve conduction study); and (b) improvement of at least 1 point of the total Overall Neuropathy Limitations Scale score after vitamin B12 treatment. RESULTS: Nine patients were identified. Serum B12 level was low in only four. Four patients had sensorimotor (predominantly sensory) axonal polyneuropathy while five had only sensory neuronopathy. Six improved in less than 1 month after B12 supplementation. CONCLUSION: B12-responsive neuropathy is a more heterogeneous group of neuropathy than previously described. B12 deficiency is a cause of peripheral neuropathy and should systematically be ruled out in the clinical setting of idiopathic neuropathy or sensory neuronopathy because of potential reversibility. ABBREVIATIONS: B12: vitamin B12; CMAP: compound muscle action potentials; DRG: dorsal root ganglia; ENMG: electroneuromyography; MCCT: motor central conduction time; MEP: motor evoked potentials; MMA: methylmalonic acid; MMCoAM: L-methylmalonyl-CoenzymeA mutase; ONLS: overall neuropathy limitations scale; SCV: sensory conduction velocities; SNAP: sensory nerve action potentials; SNN: sensory neuronopathy; SSS: SNAP sum score.

Factors correlating to the propensity of general practitioners to substitute borderline vitamin B12 deficiency.

OBJECTIVE: This study aims to identify factors which correlate to the propensity of general practitioners (GPs) to prescribe supplementation for borderline vitamin B12 deficiency. DESIGN: Cross-sectional surveys were distributed in person. SETTING: Conferences held in Cairns, Palm Cove Beach, Mt Isa; educational meetings in Atherton; and meetings with individual general practices within the Cairns and Hinterland region. All located in Queensland, Australia. SUBJECTS: 128 practicing GP specialists and registrars (practitioners in training). MAIN OUTCOME MEASURES: Responses to the Likert scale statements with its five options scaling from 'strongly disagree' to 'strongly agree' were recoded to have binary outcomes for analysis. RESULTS: A survey response rate of 89% was achieved. Participants who felt patient demands influence the management of borderline vitamin B12 deficiency were more likely to prescribe supplementation (OR 2.4, p = 0.037). Participants who perceived an overuse of vitamin B12 were less likely to prescribe B12 (OR 0.39, p = 0.019). Participants who often saw patients with vitamin B12 deficiency were less likely to request for the complementary biomarkers plasma methylmalonic acid or total homocysteine (OR 0.41, p = 0.045). CONCLUSIONS: The identified disparity to prescribe vitamin B12 for borderline deficiency may be described as an attempt in the GP collective to seek a balance between being the patient's or the society's doctor. We propose that relevant authorities try to reduce this disparity by describing a management strategy for borderline vitamin B12 deficiency. Key points General practitioners hold different thresholds for commencing supplementation in cases of borderline vitamin B12 deficiency. Participants from Australia were asked to fill out a cross-sectional survey to explore factors which correlate with the propensity to prescribe in clinical practice. Our study identified that patient demands and a practitioner's perception of whether there is an overuse of vitamin B12 in the community influenced the propensity to treat for deficiency. The results give insight into reasons for initiating supplementation, and will help inform general practitioners on their current management.

The changing cost to prevent diabetes: A retrospective analysis of the Diabetes Prevention Program.

OBJECTIVES: Diabetes prevention interventions are poorly implemented. While health care costs generally increase, 2 factors affect the relative cost of diabetes prevention interventions: the declining cost of metformin (even without insurance) and the new recommendation for vitamin B12 monitoring during metformin treatment. The study's objective was to update the relative health system cost estimate of metformin for diabetes prevention by incorporating the current health system cost of metformin and the cost of addressing potential metformin-associated vitamin B12 deficiency. The study was designed to assess whether metformin with vitamin B12 supplementation is a cost-saving measure for diabetes prevention and for the updated cost estimate to be useful in assessing future implementation studies. METHODS: In 2012, the Diabetes Prevention Program Research Group published detailed per capita total direct health system costs for the Diabetes Prevention Program (DPP) and the Diabetes Prevention Program Outcomes Study (DPPOS). The present analysis incorporated the declining cost of metformin and the increasing cost of metformin monitoring into the detailed per capita health system costs found in the DPP and DPPOS. The updated costs were used to assess the total cost of metformin use for diabetes prevention relative to placebo and lifestyle intervention. RESULTS: The current health system cost to acquire metformin ranges from $0 to $72 per year. The estimated health system cost to address potential metformin-associated vitamin B12 deficiency is $28 per metformin-treated patient per year. The 10-year total health system cost for metformin in diabetes prevention can decrease by $329 or increase by $21 depending on the cost to acquire metformin. Compared with placebo, the unadjusted cost savings of metformin is generally maintained, although it may double or quadruple depending on how metformin is acquired by patients. Metformin with vitamin B12 supplementation remained less costly and less effective than lifestyle intervention. CONCLUSION: Metformin is generally more cost-saving for diabetes prevention than previously reported because of decreasing costs for patients to acquire metformin. The cost savings was increased despite increased management cost associated with addressing metformin-associated vitamin B12 deficiency.

An infant and mother with severe B12 deficiency: vitamin B12 status assessment should be determined in pregnant women with anaemia.

The vitamin B12 status of infants depends on maternal B12 status during pregnancy, and during lactation if breastfed. We present a 9-month-old girl who was admitted to the metabolic unit for assessment of developmental delay. She was exclusively breastfed and the introduction of solids at 5 months was unsuccessful. Investigations revealed pancytopenia, undetectable B12 and highly elevated methylmalonic acid and homocysteine. Methylmalonic acid and homocysteine normalised following B12 injections. Marked catch-up of developmental milestones was noted after treatment with B12. Investigations of parents showed normal B12 in the father and combined B12 and iron deficiency in the mother. Maternal B12 deficiency, most likely masked by iron deficiency, led to severe B12 deficiency in the infant. Exclusive breastfeeding and a subsequent failure to wean exacerbated the infant's B12 deficiency leading to developmental delay. This case highlights the need for development of guidelines for better assessment of B12 status during pregnancy.

Informing disinvestment with limited evidence: cobalamin deficiency in the fatigued.

OBJECTIVES: Health technology reassessment and disinvestment can be difficult due to uncertainties regarding available evidence. Pathology testing to investigate cobalamin (vitamin B12) deficiency is a strong case in point. We conducted a 3-month economic evaluation of five strategies for diagnosing and treating cobalamin deficiency in adult patients hypothetically presenting with new unexplained fatigue in the primary care setting. The first consultation per patient was considered. Screening tests other than serum cobalamin were not included. METHODS: A cost-effectiveness analysis was undertaken using a decision tree to represent the diagnostic / treatment pathways, with relevant cost and utility scores assigned to different stages in the evaluation process. Input parameter values were estimated from published evidence, supplemented by expert opinion, with sensitivity analysis undertaken to represent parameter uncertainty. RESULTS: Ordering serum vitamin B12 to assess cobalamin deficiency among patients with unexplained fatigue was not cost-effective in any patient population, irrespective of pretest prevalence of this deficiency. For patients with a pretest prevalence above 1 percent, treating all with oral vitamin B12 supplements without testing was most cost-effective, whereas watchful waiting with symptoms monitoring was most cost-effective for patients with lower pretest prevalence probabilities. CONCLUSIONS: Substantial evidence gaps exist for parameter estimation: questionable cobalamin deficiency levels in the fatigued; debatable treatment methods; unknown natural history of the condition. Despite this, we reveal a robust path for disinvestment decision making in the face of a paradox between the evidence required to inform disinvestment compared with its paucity in informing initial funding decisions.

Assessment of functional and structural damage in brain parenchyma in patients with vitamin B12 deficiency: A longitudinal perfusion and diffusion tensor imaging study.

INTRODUCTION: Vitamin B12 deficiency may cause neural tissue damage. Even in advanced stages, conventional imaging of brain usually appears normal in vitamin B12 deficient patients. The aim of this study was to assess the structural and functional changes in brain of patients with vitamin B12 deficiency before and after six weeks of vitamin B12 supplementation using diffusion tensor imaging and pseudo-continuous arterial spin labelling (PCASL). METHODS: MR imaging including DTI and PCASL and neuropsychological tests (NPT) were performed in 16 patients with vitamin B12 deficiency and 16 controls before and after 6weeks of therapy. Cerebral blood flow (CBF) derived from PCASL and DTI indices was calculated in brain of patients with vitamin B12 deficiency and controls. RESULTS: Patient with vitamin B12 deficiency showed altered neuropsychological scores and altered CBF as well as fractional anisotropy (FA) values in various brain regions as compared with controls. Both CBF values and neuropsychological scores showed complete reversibility at 6weeks post therapy. Though FA values showed significant recovery, it failed to show complete recovery. CONCLUSION: Our results suggest that micro-structural recovery lags behind functional recovery in patients with vitamin B12 deficiency following therapy and CBF change may be used as an early predictor of complete recovery in patients with B12 deficiency.

Diffusion tensor tractography and neuropsychological assessment in patients with vitamin B12 deficiency.

INTRODUCTION: Structural imaging of the brain does not demonstrate any changes in a vast majority of patients with vitamin B12 deficiency, even in advanced stages. In this study, we aimed to assess and correlate the functional integrity of the brain fiber tracts using diffusion tensor tractography with neuropsychological examination in patients with vitamin B12 deficiency. METHODS: The study was conducted at two tertiary care centers. Thirty-two patients with vitamin B12 deficiency were enrolled and subjected to diffusion tensor tractography, as an extension of diffusion tensor imaging, and neuropsychological assessment. Tests of significance were done to detect changes, pre- and post-vitamin B12 supplementation in the diffusivity parameters (fractional anisotropy and mean diffusivity) and the neuropsychological test scores. RESULTS: Statistically significant changes were observed in the diffusivity parameters and the neuropsychological test scores between the controls and the patients with vitamin B12deficiency in the pre- and post-treatment phases. CONCLUSIONS: This is the first study to evaluate the diffusion tensor tractography (DTT) parameters in the light of clinical neuropsychological assessment in patients with vitamin B12 deficiency. Utilization of DTT parameters may antedate structural changes and may quantify the neurocognitive deficits.

Vitamin B12 intramuscular injections versus oral supplements: a budget impact analysis.

BACKGROUND: Vitamin B12 deficiency can lead to adverse health effects such as anemia and, in some cases, permanent neurologic damage. In Canada, patients with vitamin B12 deficiency are typically given intramuscular injections, which incur considerable cost and inconvenience. The clinical evidence-based analysis has found that oral supplementation is as effective as intramuscular injections. OBJECTIVES: This economic analysis aimed to estimate the cost savings of switching from intramuscular injections to high-dose oral supplements for patients aged 18 years and older with confirmed vitamin B12 deficiency. DATA SOURCES: Population-based administrative databases for Ontario were used to identify patients receiving vitamin B12 intramuscular injections in any fiscal year between 2006 and 2011. The Ontario Drug Benefit (ODB) database was used to identify patients who were prescribed vitamin B12 injections, and the Ontario Health Insurance Plan database was used to identify all physician claims for intramuscular injections as well as laboratory tests assessing vitamin B12 levels. The Registered Physicians Database was used to identify the type of physician; the analysis was restricted to family physicians and internists. REVIEW METHODS: Two cohorts of patients were identified. For cohort 1, the ODB database was used to identify patients who were prescribed vitamin B12 injections. Those covered under the ODB are 65 years of age or older and are economically deprived. A second cohort was created to capture those 18 to 64 years of age receiving injections. Cohort 2 consisted of patients (not in cohort 1) who received 6 or more intramuscular injections within 1 year and had a laboratory test 2 months before the intramuscular injection claim. Physician experts were consulted to estimate the resources and costs of converting patients to oral supplements. The Ministry of Health and Long-Term Care perspective was taken, and all costs are expressed in 2013 Canadian dollars. RESULTS: The budget impact analysis demonstrated costs of $2.8 million to the Ministry of Health and Long-Term Care in the first year of conversion; however, in subsequent years there are savings of $4.2 million per year. The cumulative 5-year budget impact demonstrates savings of $14.2 million to the health care system. LIMITATIONS: This analysis represents the cost of conversion for those currently receiving intramuscular injections. There are no conversion costs for those who are prescribed oral supplements as an initial therapy, and so the savings could be even greater than reported. As well, an underlying assumption of this analysis is that patients will comply with oral supplementation. CONCLUSIONS: Over 5 years, there are savings of $14.2 million to the health care system from switching to vitamin B12 oral supplements. PLAIN LANGUAGE SUMMARY: Vitamin B12 deficiency has long been thought to be associated with dementia and other neurocognitive disorders. In a separate report, Health Quality Ontario (HQO) reviewed the published research on this issue and found only weak evidence that vitamin B12 deficiency is associated with the onset of dementia. That review also found moderate evidence that treatment with vitamin B12 does not improve dementia and that oral supplements are as effective as injections of vitamin B12. In 2010, more than 2.9 million serum vitamin B12 tests were performed in Ontario at a cost of $40 million. Each year, approximately 110,000 residents receive vitamin B12 injections to boost their levels of vitamin B12. HQO commissioned an economic analysis to estimate the cost savings of switching from vitamin B12 injections to high-dose oral supplements for patients aged 18 years and older with confirmed B12 deficiency. This study concluded that the Ontario health care system could save $14.5 million in 5 years by switching to oral supplements, assuming that patients took the oral supplements as required.

Vitamin B12 and cognitive function: an evidence-based analysis.

BACKGROUND: More than 2.9 million serum vitamin B12 tests were performed in 2010 in Ontario at a cost of $40 million. Vitamin B12 deficiency has been associated with a few neurocognitive disorders. OBJECTIVE: To determine the clinical utility of B12 testing in patients with suspected dementia or cognitive decline. METHODS: Three questions were addressed: Is there an association between vitamin B12 deficiency and the onset of dementia or cognitive decline? Does treatment with vitamin B12 supplementation improve cognitive function in patients with dementia or cognitive decline and vitamin B12 deficiency? What is the effectiveness of oral versus parenteral vitamin B12 supplementation in those with confirmed vitamin B12 deficiency? A literature search was performed using MEDLINE, Embase, EBSCO Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the Centre for Reviews and Dissemination database, from January 2002 until August 2012. RESULTS: Eighteen studies (7 systematic reviews and 11 observational studies) were identified to address the question of the association between B12 and the onset of dementia. Four systematic reviews were identified to address the question of the treatment of B12 on cognitive function. Finally, 3 randomized controlled trials were identified that compared oral B12 to intramuscular B12. CONCLUSIONS: Based on very low quality evidence, there does appear to be an association between elevated plasma homocysteine levels (a by-product of B vitamins) and the onset of dementia. Based on moderate quality evidence, but with less than optimal duration of follow-up, treatment with B12 supplementation does not appreciably change cognitive function. Based on low to moderate quality of evidence, treatment with vitamin B12 and folate in patients with mild cognitive impairment seems to slow the rate of brain atrophy. Based on moderate quality evidence, oral vitamin B12 is as effective as parenteral vitamin B12 in patients with confirmed B12 deficiency. PLAIN LANGUAGE SUMMARY: Low levels of vitamin B12 have been associated with neurocognitive disorders. This evidence-based analysis assessed the usefulness of serum vitamin B12 testing as it relates to brain function. This review found very low quality evidence that suggests a connection between high plasma homocysteine levels (a by-product of B vitamin metabolism in the body) and the onset of dementia. Moderate quality of evidence indicates treatment with vitamin B12 does not improve brain function. Moderate quality of evidence also indicates treatment using oral vitamin B12 supplements is as effective as injections of vitamin B12.

Oral versus intramuscular administration of vitamin B12 for the treatment of patients with vitamin B12 deficiency: a pragmatic, randomised, multicentre, non-inferiority clinical trial undertaken in the primary healthcare setting (Project OB12).

BACKGROUND: The oral administration of vitamin B12 offers a potentially simpler and cheaper alternative to parenteral administration, but its effectiveness has not been definitively demonstrated. The following protocol was designed to compare the effectiveness of orally and intramuscularly administered vitamin B12 in the treatment of patients ≥65 years of age with vitamin B12 deficiency. METHODS/DESIGN: The proposed study involves a controlled, randomised, multicentre, parallel, non-inferiority clinical trial lasting one year, involving 23 primary healthcare centres in the Madrid region (Spain), and patients ≥65 years of age. The minimum number of patients required for the study was calculated as 320 (160 in each arm). Bearing in mind an estimated 8-10% prevalence of vitamin B12 deficiency among the population of this age group, an initial sample of 3556 patients will need to be recruited. Eligible patients will be randomly assigned to one of the two treatment arms. In the intramuscular treatment arm, vitamin B12 will be administered as follows: 1 mg on alternate days in weeks 1 and 2, 1 mg/week in weeks 3-8,and 1 mg/month in weeks 9-52. In the oral arm, the vitamin will be administered as: 1 mg/day in weeks 1-8 and 1 mg/week in weeks 9-52. The main outcome variable to be monitored in both treatment arms is the normalisation of the serum vitamin B12 concentration at weeks 8, 26 and 52; the secondary outcome variables include the serum concentration of vitamin B12 (in pg/ml), adherence to treatment, quality of life (EuroQoL-5D questionnaire), patient 3satisfaction and patient preferences. All statistical tests will be performed with intention to treat and per protocol. Logistic regression with random effects will be used to adjust for prognostic factors. Confounding factors or factors that might alter the effect recorded will be taken into account in analyses. DISCUSSION: The results of this study should help establish, taking quality of life into account, whether the oral administration of vitamin B12 is an effective alternative to its intramuscular administration. If this administration route is effective, it should provide a cheaper means of treating vitamin B12 deficiency while inducing fewer adverse effects. Having such an alternative would also allow patient preferences to be taken into consideration at the time of prescribing treatment. TRIAL REGISTRATION: This trial has been registered with ClinicalTrials.gov, number NCT 01476007, and under EUDRACT number 2010-024129-20.

Oral or intramuscular vitamin B12?

Vitamin B(12) deficiency is common, becoming more so with age, and estimates of its population prevalence have ranged from 1.5% to 15%. If untreated, it can lead to megaloblastic anaemia and irreversible neurological complications. In the UK, the usual treatment is regular intramuscular injections of hydroxocobalamin. High-dose oral vitamin B(12) replacement is standard practice in some other countries and less costly. Here we review issues around adopting an oral vitamin B(12) replacement regimen more widely in the UK.

Comparing costs of intramuscular and oral vitamin B12 administration in primary care: a cost-minimization analysis.

OBJECTIVE: To establish whether savings could be made by changing patients from intramuscular to high doses of oral vitamin B12 in primary care without compromising their wellbeing. METHODS: Cost-minimization analysis from a UK perspective, using secondary data obtained from the literature available and expert opinion. RESULTS: The cost of the resources used to treat patients with vitamin B12 deficiency with intramuscular vitamin B12 was calculated as between 55.99 pounds (83.1 Euro) and 99.99 pounds (148.5 Euro) per year. The cost of treating patients with high doses of oral vitamin B12 during the first year was between 125.55 pounds (186.5 Euro) and 248.55 pounds (369.1 Euro). However, once patients receiving intramuscular treatment had been converted to oral treatment, or in new patients treated orally from the outset, the cost was 35.55 pounds per year (52.8 Euro). One variable, home visits, had a high impact on the calculations. CONCLUSION: Switching patients with vitamin B12 deficiency from intramuscular to high-dose oral therapy and treating patients newly diagnosed with vitamin B12 deficiency with oral vitamin B12 from the outset could save resources in the medium and long term, and in newly diagnosed patients. Savings would come particularly in the form of nursing time.

Cobalamin-responsive disorders in the ambulatory care setting: unreliability of cobalamin, methylmalonic acid, and homocysteine testing.

Early recognition of cobalamin (Cbl)-responsive disorders in the ambulatory care setting is essential to prevent irreversible neurologic deficits. However, diagnostic algorithms using Cbl, methylmalonic acid (MMA), and homocysteine (HCys) measurements reflect studies in academic centers, and their negative predictive values have not been established. Thus, records of 456 ambulatory patients evaluated for Cbl deficiency at a staff model HMO were reviewed. Pretherapy Cbl, MMA, and HCys values in individual patients varied by 23%, 23%, and 17%, respectively, over 2 to 6 weeks. Hematologic or neurologic responses to pharmacologic doses of Cbl occurred in 37 of the 95 evaluable patients. In these patients, pretherapy Cbl, MMA, and HCys values were normal in 54%, 23%, and 50%, respectively. If therapy had been restricted to symptomatic patients with both low or intermediate Cbl levels and increased metabolite values, 63% of responders would not have been treated. Twenty-five patients did not respond to treatment, including 5 of 11 patients (45%) with low Cbl, 22 of 49 patients (45%) with high MMA, and 13 of 30 patients (43%) with high HCys values. It is concluded that Cbl, MMA, and HCys levels fluctuate with time and neither predict nor preclude the presence of Cbl-responsive hematologic or neurologic disorders.

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.