Causal inference between pernicious anemia and cancers: a bidirectional two-sample mendelian randomization analysis

BACKGROUND

Observational study investigated the association between pernicious anemia (PA) and cancers. However, with the exception of gastric cancer, the results are mostly contradictory. The purpose of this study was to investigate the potential causal relationship between PA and cancers through bidirectional two-sample Mendelian randomized (MR) analysis.

METHODS

The European sample FinnGen project provided the genetic summary data for PA and 20 site-specific cancers. This bidirectional two-sample MR design mainly used the inverse variance weighting (IVW) method to evaluate the causal relationship between PA and cancer risk. Benjamini-Hochberg correction was performed to reduce the bias caused by multiple tests.

RESULTS

Our study shows that there was a causal relationship between PA and gastric cancer, prostate cancer, testicular cancer and malignant melanoma of skin, and there was a reverse causal relationship between prostate cancer or gastric cancer and PA (P < 0.05). After Benjamini-Hochberg correction test, there was still a causal correlation between PA and gastric or prostate cancer (P' < 0.05), while there was only an implied causal association between PA and testicular cancer and malignant melanoma of skin (P'> 0.05). There was still a reverse causal relationship between gastric cancer and PA (P'< 0.05), while prostate cancer shows an implied reverse causal relationship(P'> 0.05). In addition, MR-Egger and MR-PRESSO tests showed no significant horizontal pleiotropy.

CONCLUSIONS

PA may be genetically associated with testicular cancer, prostate cancer, gastric cancer, and malignant melanoma of skin.

Vitamin B12 deficiency-induced megaloblastic anemia in a pediatric patient with autism spectrum disorder with a chronically unbalanced diet

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by a lack of behavioral flexibility and stereotyped language. Food selectivity is common among children with ASD because of their persnickety nature. A prolonged unbalanced diet results in an increased risk of several diseases, such as iron deficiency anemia, scurvy, rickets, dry eye, and Wernicke encephalopathy. However, no cases of megaloblastic anemia have been reported to date. We report the case of an 11-year-old boy with ASD who developed megaloblastic anemia due to vitamin B12 deficiency. He had a prolonged history of selective eating for more than 10 years. His nutritional status on admission was poor, and he had low weight and short stature. His food selectivity was so strong that intervention to expand diet variety was unsuccessful. A developmental-behavioral pediatrician found that the patient had visual dominance and could take some medications when suffering from a minor illness. Nutritional supplements were selected after consultation with a nutritionist. Although compulsory treatment was necessary during the acute phase, the therapy was continued at home. With multidisciplinary intervention tailored to the patient and his parents' characteristics, his nutritional status improved in a few months.

A new perspective on vitamin B12 deficiency in rheumatology: a case-based review

Vitamin B12 (cobalamin) deficiency is common in patients with rheumatic diseases. Pernicious anemia is a well-known cause, but recent reports suggest that autoimmune-derived deficiency may not be limited to this cause alone. Symptoms of low vitamin B12 concentration are often deceptive, mimicking and overlapping with symptoms of other conditions. Neuropsychiatric manifestations, anemia, and fatigue are frequently attributed to a rheumatic disease without further evaluation. In this study, we present three cases of patients with neuropathic pain, depression, fatigue, and muscle weakness, initially attributed to a rheumatic disease, which almost completely resolved after implementing vitamin B12 supplementation. Furthermore, we provide an overview of current scientific reports regarding the potential use of cobalamin in rheumatology. Treatment of pain and neuropathy, often very challenging in long-lasting rheumatic diseases, can be more effective after a course of vitamin B12, even when no apparent deficiency is detected in laboratory tests. Considering recent research demonstrating vitamin B12's nerve-protecting properties, we recommend that physicians should assess vitamin B12 levels early in the diagnostic process of rheumatic diseases. In specific cases, physicians should consider cobalamin supplementation regardless of vitamin B12 serum concentration.

Neurological complications of excessive recreational nitrous oxide use: a case series based on a text mining algorithm

BACKGROUND

The recreational use of nitrous oxide (N2O) has gained popularity over recent years. We present a case series of excessive N2O users with neurological complications.

METHODS

In this retrospective three-centre study, we used a text mining algorithm to search for patients who used N2O recreationally and visited a neurologist.

RESULTS

We identified 251 patients. The median duration of N2O use was 11 months (interquartile range [IQR], 3-24) and the median amount of N2O used per occasion 1.6 kg (IQR 0.5-4.0). Clinically, polyneuropathy (78%), myelopathy (41%), and encephalopathy (14%) were the most common diagnoses. An absolute vitamin B12 deficiency of < 150 pmol/L was found in 40% of cases. In 90%, at least one indicator of functional vitamin B12 status (vitamin B12, homocysteine, or methylmalonic acid) was abnormal. MRI showed signs of myelopathy in 30/55 (55%) of cases. In 28/44 (64%) of those who underwent electromyography, evidence of axonal polyneuropathy was found. Most (83%) patients were treated with vitamin B12 supplementation, and 23% were admitted to the hospital. Only 41% had follow-up for ≥ 30 days, and 79% of those showed partial or complete recovery.

CONCLUSIONS

In this case series of excessive N2O users, we describe a high prevalence of polyneuropathy, myelopathy, and encephalopathy. Stepwise testing for serum levels of vitamin B12, homocysteine, and methylmalonic acid may support the clinical diagnosis. Due to low sensitivity, MRI of the spinal cord and electromyography have limited value. Effective treatment should incorporate supplementation of vitamin B12 and strategies to prevent relapses in N2O use.

Iron and Vitamin B12 Deficiency in Patients with Autoimmune Gastritis and Helicobacter pylori Gastritis: Results from a Prospective Multicenter Study

INTRODUCTION

Iron and vitamin B12 deficiencies are common in patients with atrophic gastritis, but there are limited data on the prevalence of these deficiencies in different types of atrophic gastritis.

METHODS

This multicenter, prospective study assessed micronutrient concentrations in histologically confirmed autoimmune gastritis (AIG, n = 45), Helicobacter pylori-related non-autoimmune gastritis (NAIG, n = 109), and control patients (n = 201). A multivariate analysis was performed to determine factors influencing those deficiencies.

RESULTS

The median vitamin B12 concentration was significantly lower in AIG (367.5 pg/mL, Q1, Q3: 235.5, 524.5) than in NAIG (445.0 pg/mL, Q1, Q3: 355.0, 565.0, p = 0.001) and control patients (391.0 pg/mL, Q1, Q3: 323.5, 488.7, p = 0.001). Vitamin B12 deficiency was found in 13.3%, 1.5%, and 2.8% of AIG, NAIG, and control patients, respectively. Similarly, the median ferritin concentration was significantly lower in AIG (39.5 ng/mL, Q1, Q3: 15.4, 98.3 ng/mL) than in NAIG (80.5 ng/mL, Q1, Q3: 43.6, 133.9, p = 0.04) and control patients (66.5 ng/mL, Q1, Q3: 33.4, 119.8, p = 0.007). Iron deficiency and iron deficiency adjusted to CRP were present in 28.9% and 33.3% of AIG, 12.8% and 16.5% of NAIG, and 12.9% and 18.4% of controls, respectively. Multivariate analysis demonstrated that AIG patients had a higher risk of developing vitamin B12 deficiency (OR: 11.52 [2.85-57.64, p = 0.001]) and iron deficiency (OR: 2.92 [1.32-6.30, p = 0.007]) compared to control patients. Factors like age, sex, and H. pylori status did not affect the occurrence of vitamin B12 or iron deficiency.

CONCLUSION

Iron and vitamin B12 deficiencies are more commonly observed in patients with AIG than in those with NAIG or control patients. Therefore, it is essential to screen for both iron and vitamin B12 deficiencies in AIG patients and include the treatment of micronutrient deficiencies in the management of atrophic gastritis patients.

B12 Deficiency is the Commonest Cause of Anaemia During Pregnancy in Northern India: Study from a Tertiary Care Institute

Iron deficiency anemia is considered the leading cause of anemia during pregnancy; however, there is a lack of comprehensive studies on the etiological factors of anemia in pregnant women. The objective of this study was to systematically investigate the causes of anemia in pregnancy. Five hundred women with hemoglobin levels < 11 g/dl between 6 and 40 weeks of pregnancy underwent a complete hemogram, iron studies, serum folate, serum B12, serum copper, and serum zinc level assessments using standard methods. The median age of the patients was 26 years (range 24-29 years). The majority of patients were in the third trimester (449/500, 89.8%). Among the patients, 325 (65%) had vitamin B12 deficiency, with 159 (31.8%) having isolated B12 deficiency and 142 (28.4%) having combined B12 and iron deficiency. Isolated iron deficiency anemia was present in 74 patients (14.8%). Additionally, 28 patients (5.6%) had beta-thalassemia minor, and anemia of chronic disease was found in 17.2% (86) of the patients. Vitamin B12 deficiency was the most common cause of anemia, followed by combined B12 and iron deficiency. Further studies in diverse populations are warranted as they have broader implications for nutrient supplementation during pregnancy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12288-023-01682-x.

Multiomic analysis in fibroblasts of patients with inborn errors of cobalamin metabolism reveals concordance with clinical and metabolic variability

BACKGROUND

The high variability in clinical and metabolic presentations of inborn errors of cobalamin (cbl) metabolism (IECM), such as the cblC/epicblC types with combined deficits in methylmalonyl-coA mutase (MUT) and methionine synthase (MS), are not well understood. They could be explained by the impaired expression/activity of enzymes from other metabolic pathways.

METHODS

We performed metabolomic, genomic, proteomic, and post-translational modification (PTM) analyses in fibroblasts from three cblC cases and one epi-cblC case compared with three cblG cases with specific MS deficits and control fibroblasts.

FINDINGS

CblC patients had metabolic profilings consistent with altered urea cycle, glycine, and energy mitochondrial metabolism. Metabolomic analysis showed partial disruption and increased glutamate/ketoglutarate anaplerotic pathway of the tricarboxylic acid cycle (TCA), in patient fibroblasts. RNA-seq analysis showed decreased expression of MT-TT (mitochondrial tRNA threonine), MT-TP (mitochondrial tRNA proline), OXCT1 (succinyl CoA:3-oxoacid CoA transferase deficiency), and MT-CO1 (cytochrome C oxidase subunit 1). Proteomic changes were observed for key mitochondrial enzymes, including NADH:ubiquinone oxidoreductase subunit A8 (NDUFA8), carnitine palmitoyltransferase 2 (CPT2), and ubiquinol-cytochrome C reductase, complex III subunit X (UQCR10). Propionaldehyde addition in ornithine aminotransferase was the predominant PTM in cblC cells and could be related with the dramatic cellular increase in propionate and methylglyoxalate. It is consistent with the decreased concentration of ornithine reported in 3 cblC cases. Whether the changes detected after multi-omic analyses underlies clinical features in cblC and cblG types of IECM, such as peripheral and central neuropathy, cardiomyopathy, pulmonary hypertension, development delay, remains to be investigated.

INTERPRETATION

The omics-related effects of IECM on other enzymes and metabolic pathways are consistent with the diversity and variability of their age-related metabolic and clinical manifestations. PTMs are expected to produce cumulative effects, which could explain the influence of age on neurological manifestations.

FUNDING

French Agence Nationale de la Recherche (Projects PREDICTS and EpiGONE) and Inserm.

Pseudo-thrombotic Microangiopathy - An Unusual Presentation of Cobalamin Deficiency

Vitamin B12 is a water-soluble vitamin cofactor for many enzymatic reactions in the body. It plays a vital role in the normal maturation of red blood cells and in producing proteins needed for normal neurological function. The most common presentations of vitamin B12 deficiency are hematological abnormalities and neurological manifestations. Pseudo-thrombotic microangiopathy, a syndrome of hemolysis and thrombocytopenia, may mimic the presentation of thrombotic microangiopathies such as thrombotic thrombocytopenic purpura, an uncommon presentation of vitamin B12 deficiency. We present the case of a 58-year-old male with no significant past medical history who presented with severe macrocytic anemia and thrombocytopenia with laboratory findings suggestive of hemolytic anemia. He was found to have vitamin B12 deficiency with positive serological markers suggesting pernicious anemia is the underlying cause. Our case demonstrates that vitamin B12 deficiency should be considered in cases of suspected thrombotic microangiopathy, especially in the setting of significantly elevated lactate dehydrogenase levels and low reticulocyte count to avoid the initiation of unnecessary and expensive treatment modalities such as plasmapheresis.

Growth and Nutritional Biomarkers in Brazilian Infants with Cow's Milk Allergy at Diagnosis and 18-Month Follow-Up: A Prospective Cohort Study

Purpose

This study aimed to describe the growth, body protein status, and micronutrient biomarkers of Brazilian infants with cow's milk allergy (CMPA) at baseline and at 18 months of follow-up in comparison with their healthy peers.

Methods

Thirty infants with CMPA younger than six months of age were included in this longitudinal study, and their nutritional status was compared with that of 24 non-allergic age-matched children. Anthropometric measurements were used to assess growth, and blood and urine samples were analyzed for protein and micronutrient status. Mixed linear models adjusted for birth weight, socioeconomic status, infant feeding at baseline, weight-for-age, C-reactive protein, serum albumin, micronutrient dietary supplementation, and salt consumption were employed to evaluate the evolution of nutritional parameters throughout the follow-up period.

Results

Overall, the mean age of the children at enrolment was 2.9 (standard deviation 1.7) months, and 29 children (53.7%) were male. Infants with CMPA showed a higher prevalence of functional iron depletion (transferrin saturation <20) (p=0.027), lower serum ferritin (p=0.009), and lower urinary iodine (p=0.034) levels than non-allergic children at baseline. Patients with CMPA showed a higher increment in weight-for-age and length-for-age over time than those in the control group (p<0.01). Mixed linear analyses showed a significantly lower increase in serum vitamin B12 (s-B12) (p=0.001) and urinary iodine (p<0.001) concentrations over time compared to the control group.

Conclusion

Infants with CMPA on a cow's milk elimination diet had a higher weight and length at 18 months of follow-up but showed signs of inadequate iron, iodine, and B-12 vitamin status.

Bidirectional association between diabetic peripheral neuropathy and vitamin B12 deficiency: Two longitudinal 9-year follow-up studies using a national sample cohort

AIM

This study aims to investigate the association among metformin use, vit B12 deficiency, and DPN occurrence in diabetes.

METHODS

This retrospective, propensity-matched cohort study was performed using National Health Insurance Service database - National Sample Cohort in South Korea. Study 1 analyzed DPN incidence according to vit B12 deficiency and study 2 analyzed vit B12 deficiency incidence according to the presence/absence of DPN. Moreover, we compared the results with respect to metformin use.

RESULTS

In study 1, DPN incidence per 10000 person-year (PY) was 179.7 and 76.6 in the vit B12 and non-vit B12 deficiency groups, respectively. The adjusted HR was 1.32 (95% CI; 1.21-1.44, P < 0.05) and metformin use elicited a more significant effect of DPN occurrence in patient with vit B12 deficiency (HR: 5.76 (95% CI; 5.28-6.29). In study 2, vit B12 deficiency incidence per 10000 PY was 250.6 and 129.4 in the DPN and non-DPN groups, respectively. The adjusted HR was 2.44 (95% CI; 2.24-2.66, P < 0.05), however, metformin prescription was associated with the reduced incidence of vit B12 deficiency in DPN patients (HR 0.68 (95% CI; 0.62-0.74, P < 0.05).

CONCLUSION

DPN occurrence increased in diabetes with vit B12 deficiency and the incidence of vit B12 deficiency was also high in DPN patients. However, metformin showed opposite effects in both cohorts. Further studies clarifying the causal relationship among DPN occurrence, vit B12 deficiency, and metformin use are warranted.

Congenital thrombotic thrombocytopenic purpura masquerading as vitamin B12 deficiency

INTRODUCTION

Congenital thrombotic thrombocytopenic purpura (CTTP), also called Upshaw-Schulman syndrome (USS), is a rare autosomal recessive disorder resulting from the deficiency of the ADAMTS13. CTTP is characterized by the formation of platelet-rich thrombi in small vessels of multiple organs, resulting in thrombocytopenia and microangiopathic hemolytic anemia, eventually leading to organ failure.

CASE REPORT

We present a case of an 11-month-old male infant with CTTP lacking classic features of the disease. Instead, his clinical picture portrayed vitamin B12 deficiency, leading to misdiagnosis and subsequent treatment delay.

CONCLUSION

This case led to the conclusion that congenital TTP should be suspected in case of vitamin B12 deficiency if the child does not respond to the vitamin B12 replacement therapy. We also emphasize that management for CTTP should be started at its earliest in case of increased clinical suspicion to avoid worse outcomes, especially in countries lacking rapid availability of enzyme assay.

Imerslund-Gräsbeck syndrome: a comprehensive review of reported cases

Imerslund-Gräsbeck syndrome (IGS) is a rare autosomal recessive disorder characterized by vitamin B12 malabsorption. Most patients present with non-specific symptoms attributed to vitamin B12 deficiency, and proteinuria. Patients may if untreated, develop severe neurocognitive manifestations. If recognized and treated with sufficient doses of vitamin B12, patients recover completely. We provide, for the first time, an overview of all previously reported cases of IGS. In addition, we provide a complete review of IGS and describe two new patients.

Bilateral sixth nerve palsy with subdural hematoma: a unique presentation of B12 deficiency

Vitamin B12 is inextricably associated with the development and maintenance of neuronal functions. It is classically associated with subacute combined degeneration and peripheral neuropathy; however, cranial neuropathy is uncommon. We observed the rarest neurological manifestation of B12 deficiency. A 12 months infant had history of lethargy, irritability, anorexia, paleness, vomiting, and neurodevelopmental delay for 2 months. He also developed inattention and altered sleep pattern. His mother noticed bilateral inward rotation of both eyes. On examination, the infant had bilateral lateral rectus palsy. The infant was found to have anemia (7.7g/dL) and severe B12 deficiency (74pg/mL). On MRI, there was cerebral atrophy, subdural hematoma (SDH) and wide cisternal spaces and sulci. On supplementation with cobalamin, he improved clinically though mild restriction of lateral gaze on the left side persists. Follow up MRI showed significant improvement in cerebral atrophy with resolution of SDH. To date, such clinical presentation of B12 deficiency has never been reported. The authors suggest B12 supplementation for at risk population esp at antenatal stage and lactating mothers in national programs. The treatment of this condition should be initiated early to prevent long term sequelae.

Autoimmune gastritis as an unexpected cause of diarrhea in a young adult with type I diabetes: a case report

BACKGROUND

Type 1 diabetes mellitus (T1DM) is a lifelong diagnosis that involves immune-mediated damage of pancreatic beta cells and subsequent hyperglycemia, manifesting as: polyuria, polydipsia, polyphagia, and weight loss. Treatment of type 1 diabetes centers on insulin administration to replace or supplement the body's own insulin with the goal of achieving euglycemia and preventing or minimizing complications. Patients with T1DM are at risk for developing other autoimmune conditions, most commonly thyroid or celiac disease.

CASE PRESENTATION

A 20-year-old African American female with T1DM was referred by her endocrinologist to pediatric gastroenterology for 2 months of nocturnal, non-bloody diarrhea, left lower quadrant pain, and nausea; she was also being followed by neurology for complaints of lower extremity paresthesias and pain. The patient's initial lab-workup was remarkable for a low total Immunoglobulin A (IgA) level of < 6.7 mg/dL. As IgA deficiency is associated with an increased risk of celiac disease, the patient underwent upper and lower endoscopy, which was grossly unremarkable; however, histology revealed a pattern consistent with autoimmune gastritis. Subsequent serum evaluation was remarkable for an elevated fasting gastrin level and an elevated parietal cell antibody level without macrocytic anemia, iron deficiency, or vitamin B12 depletion. The patient was diagnosed with autoimmune gastritis (AIG) and subsequently initiated on parenteral B12 supplementation therapy with improvement in her neurologic and gastrointestinal symptoms.

CONCLUSION

This case illustrates the importance of recognition of red flag findings in a patient with known autoimmune disease. Following well-established health maintenance recommendations for individuals with T1DM ensures that common comorbidities will be detected. Autoimmune gastritis, while a rarer pathology in the pediatric population, deserves consideration in patients with pre-existing autoimmune conditions and new gastrointestinal or neurologic symptoms, as AIG can be associated with poor outcomes and risk of malignancy. Initial lab findings associated with an eventual diagnosis of AIG typically include anemia, iron deficiency, or Vitamin B12 deficiency. However, as demonstrated in this case, symptoms of AIG can rarely present before anemia or Vitamin B12 deficiency develops. To prevent permanent neurological damage, parenteral Vitamin B12 therapy must be considered even in the absence of Vitamin B12 deficiency, especially in those patients already experiencing neurological symptoms.

Determinants of vitamin B12 deficiency in patients with type-2 diabetes mellitus - A primary-care retrospective cohort study

BACKGROUND

Like many developed nations, the prevalence of both older people and type-2 diabetes mellitus (T2DM) in Singapore is rising. This demographic shift predisposes the population to greater risks of both frailty and its complications that can be further aggravated by vitamin B12 deficiency -a highly prevalent associated variable that is potentially modifiable. Indeed, B12 deficiency adversely impacts the neuro-cognitive, haematological, and even the immune systems; jeopardizing our aspirations for successful aging. Despite this, many patients with T2DM in primary care remain unscreened due to a lack of clear guidelines for regular B12 screening. We therefore investigated the determinants of B12 deficiency in community-dwelling patients with T2DM, with the aim of profiling patients most in need of B12-deficiency screening.

METHODS

B12 deficiency was evaluated using a retrospective cross-sectional cohort of 592 primary-care patients with T2DM, recruited from 2008 to 2011 from a Polyclinic in Singapore.

RESULTS

B12 deficiency (serum B12 < 150 pmol/L) was present in 164 (27.7%) patients and was associated with a higher "metformin daily dose" (OR = 2.79; 95% CI, 2.22-3.48, P < 0.001); "age ≥ 80 years" (OR = 2.86; 95% CI, 1.31-6.25, P = 0.008); "vegetarianism" (OR = 21.61; 95% CI, 4.47-104.44, P < 0.001); and "folate deficiency" (OR = 2.04; 95% CI, 1.27-3.28, P = 0.003). Conversely, "Prescribed B12 supplementation" was associated with a lower odds of B12 deficiency (OR = 0.37; 95% CI: 0.22-0.61, P < 0.001). The area under the receiver operating characteristic curve was 0.803 (95% CI: 0.765-0.842). "Metformin daily dose" correlated interchangeably with "Metformin 1-year cumulative dose" (r = 0.960; P < 0.01), and also associated linearly with "duration of diabetes" (B = 0.113, P < 0.0001). Independent of the duration of T2DM, 29.3% of the B12-deficient patients needed > 1 screening test before the detection of B12 deficiency.

CONCLUSIONS

Primary-care screening for B12 deficiency should be part of the annual laboratory review of patients with T2DM regardless of the duration of T2DM -especially when they are prescribed ≥ 1.5 g/day of metformin; ≥ 80 years old; vegetarian; and not prescribed B12 supplementation. Concurrent evaluation for associated folate (vitamin B9) deficiency is essential when addressing T2DM-associated B12 deficiencies. Current "Metformin daily dose" is an accurate proxy of both cumulative metformin exposure and duration of T2DM.

Vitamin B12: For more than just the treatment of megaloblastic anemia?

Vitamin B12, or cobalamin, belongs to the group of water-soluble vitamins and is ingested through food of animal origin such as eggs, milk, red meat and poultry, fish, and shellfish. Its clinical indication is the treatment of hypovitaminosis B12 administered orally or intramuscularly in the form of hydroxocobalamin. Hypovitaminosis B12 is mainly caused by deficient dietary intake (individuals with malnutrition, vegetarians or vegans, older adults, pregnant people, individuals with alcohol use disorder); when intestinal absorption is reduced (atrophic gastritis, malabsorption syndrome, gastrointestinal surgery); and for causes associated with the intake of drugs (antacids, metformin). Hypervitaminosis B12 has been associated with renal failure; liver diseases such as cirrhosis and acute-phase hepatitis; alcohol use disorder with or without liver involvement; solid tumors of the lung, liver, esophagus, pancreas, and colorectum; and in hematological malignancies such as leukemia and bone marrow dysplasia.

Clinical Course of Vitamin B12 Deficiency and Associated Risk Factors in Patients After Total Gastrectomy for Gastric Cancer

BACKGROUND/AIM

Patients are at-risk for vitamin B12 deficiency after total gastrectomy due to a lack of intrinsic factors. The aim of the study was to clarify the clinical course and risk factors for vitamin B12 deficiency after total gastrectomy for gastric cancer patients.

PATIENTS AND METHODS

Patients who underwent curative resection for gastric cancer were selected from the medical records of the Yokohama City University from 2000 to 2020. A logistic regression analysis was performed to identify risk factors for vitamin B12 deficiency.

RESULTS

We evaluated 47 patients. The median serum vitamin B12 levels before surgery were 359 pg/ml, while those at 3, 6, 9, and 12 months after surgery these were 255 pg/ml, 197.5 pg/ml, 195 pg/ml, and 206 pg/ml, respectively. Univariate analyses to identify factors associated with vitamin B12 deficiency at 6 months after surgery showed that the occurrence of postoperative complications was a significant risk factor (OR=6.347, 95%CI=1.607-25.774, p=0.009), while adjuvant chemotherapy was a marginally significantly risk factor (OR=3.562, 95%CI=0.877-14.477, p=0.076).

CONCLUSION

Almost half of the patients were diagnosed with vitamin B12 deficiency at 6 months after total gastrectomy for gastric cancer. In addition, the occurrence of postoperative complications and adjuvant chemotherapy were risk factors for vitamin B12 deficiency at 6 months after surgery.

High frequencies of vitamin B12 and folic acid deficiencies and hyperhomocysteinemia in Taiwanese male patients with oral submucous fibrosis

Background

/purpose: Oral submucous fibrosis (OSF) is a betel quid chewing-caused oral mucosal disease with progressive collagen deposition. This study evaluated whether Taiwanese male OSF patients had high frequencies of vitamin B12 and folic acid deficiencies, hyperhomocysteinemia, and serum gastric parietal cell antibody (GPCA) positivity.

Materials and methods

The blood hemoglobin (Hb), serum iron, vitamin B12, folic acid, homocysteine, and GPCA concentrations in 62 male OSF patients were measured and compared with the corresponding data in 124 age-matched male healthy control subjects.

Results

We found that 5 (8.1%), 12 (19.4%), 32 (51.6%), 31 (50.0%), 22 (35.5%), and 6 (9.7%) of the 62 male OSF patients had Hb (<13 g/dL), iron (≤70 μg/dL), vitamin B12 (≤450 pg/mL), and folic acid (≤6 ng/mL) deficiencies, hyperhomocysteinemia (>12 μM), and serum GPCA positivity, respectively. Furthermore, OSF patients had significantly higher frequencies of Hb (P = 0.006), vitamin B12 (P < 0.001), and folic acid (P < 0.001) deficiencies, hyperhomocysteinemia (P < 0.001), and serum GPCA positivity (P = 0.030) than 124 healthy control subjects. Of the 22 OSF patients with hyperhomocysteinemia, 4 had vitamin B12 deficiency only, 7 had folic acid deficiency only, and 11 had both vitamin B12 and folic acid deficiencies.

Conclusion

We conclude that Taiwanese male OSF patients have high frequencies of vitamin B12 and folic acid deficiencies, hyperhomocysteinemia, and serum GPCA positivity. The hyperhomocysteinemia in our OSF patients is predominantly due to deficiencies of either vitamin B12 or folic acid or both.

Higher frequencies of anemia, hematinic deficiencies, and gastric parietal cell antibody positivity in vitamin B12-deficient Taiwanese male oral submucous fibrosis patients

Abstract Background/purpose

Oral submucous fibrosis (OSF) is a progressive fibrotic oral mucosal disease associated with betel quid chewing. This study evaluated whether Taiwanese male OSF patients with vitamin B12 deficiency (the serum vitamin B12 level ≤ 450 pg/mL, B12-deficient OSF patients) had high frequencies of blood hemoglobin (Hb) and serum iron and folic acid deficiencies, and serum gastric parietal cell antibody (GPCA) positivity.

Materials and methods

The blood Hb and serum iron, vitamin B12, folic acid, and GPCA concentrations in 66 Taiwanese male B12-deficient OSF patients were measured and compared with the corresponding data in 132 age-matched healthy male control subjects.

Results

We found that 6 (9.1%), 19 (28.8%), 35 (53.0%), and 9 (13.6%) of the 66 B12-deficient OSF patients had blood Hb (<13 g/dL) and serum iron (≤70 μg/dL), and folic acid (≤6 ng/mL) deficiencies, and serum GPCA positivity, respectively. Furthermore, 66 OSF patients had significantly higher frequencies of blood Hb and serum iron and folic acid deficiencies, and serum GPCA positivity than 132 healthy control subjects (all P-values < 0.05). Of the 6 anemic B12-deficient OSF patients, one had macrocytic anemia, two normocytic anemia, and three thalassemia trait-induced anemia.

Conclusion

Taiwanese male B12-deficient OSF patients have high frequencies of blood Hb, serum iron and folic acid deficiencies, and serum GPCA positivity. The anemia and hematinic deficiencies in B12-deficient OSF patients are likely due to OSF symptoms and signs-caused insufficient intake, poor chewing, and malabsorption of hematinic elements from ingested food stuffs rather than the GPCA positivity.

[Prospective Cross-sectional Study on Adverse Effects of Metformin Hydrochloride on 130 Patients Type 2 Diabetic Admitted to Medical Center and Diabetes Home of Sidi Bel-Abbès.]

INTRODUCTION

MetforminHydrochloride is an antidiabetic used for many years, currently; it considered the first choice in treatment of type 2 diabetes (T2D). It decreases insulin resistance, does not induce hypoglycaemia, increases glucose utilization in the liver and skeletal muscle, and decreases hepatic glucose production. Its adverse effects (AE) are gastrointestinal, decrease in vitamin B12 absorption, abnormalities of hemogram and rarely skin reactions. The objective of this study was to report the type and frequency of AEs of MetforminHydrochloride used in the therapeutic management of T2D patients admitted to the medical center and the diabetes home of Sidi Bel-Abbès in Algeria.

MATERIALS AND METHODS

A cross-sectional descriptive study was carried out over a period of four months, from January 1st, 2017 to April 30th, 2017, involving 130 patients treated with MetforminHydrochloride consulting at Mimoun City Diabetes Home and Gambetta Diabetes Center in the town of Sidi Bel-Abbès. The primary outcome measure was the determination of the type and frequency of AEs related to normal dosages or overdose use of MetforminHydrochloride in T2D. Data were collected from patient records, using a questionnaire, and analyzed using Statistical Package for the Social Sciences, version 20 software.

RESULTS

130 patients were included, including 82 women, with a mean age of 51.08±8.85 years (30-66). One hundred and ninety-eight (198) AEs were reported, an average of 1.52 AEs per patient. Among them, 95 (47.98%) AEs are digestive disorders (30.77% of patients suffered from diarrhea, 10.77% had nausea and vomiting, 8.46% suffered from abdominal pain and bloating, 3.85% lost their taste, 7.69% complained of epigastric cramps and 11.54% of anorexia), 29 (14.65%) AEs are hypoglycaemia, 73 (36.87%) AEs are other symptoms and 1 (0.50%) EI is vitamin B12 deficiency and no cases of lactic acidosis or allergic reaction were reported. Five (3.85%) patients had a total and lasting intolerance to MetforminHydrochloride leading to its discontinuation following persistent diarrhoea.

CONCLUSION

AEs of MetforminHydrochloride used in the management of T2D patients consulting at the medical center and the Diabetes home of Sidi Bel-Abbès are frequent. Digestive disorders were the most frequent, diarrhea was very frequent and led to discontinuation of treatment in 3.85% of T2D patients, followed by nausea and vomiting, then abdominal pain, bloating and epigastric cramps, and rarely taste metallic. Hypoglycaemia was frequent following its association with insulin, the onset of headaches and fatigue were frequent, but no case of lactic acidosis or allergic reaction was reported. Due to a lack of means, the dosage of homocysteine and methylmalonic acid had not been carried out to confirm the vitamin B12 deficiency in the patient whose level was less than 200ng/mL. A precise assessment of the imputability of reported AEs is necessary.

A Rare Presentation of Pernicious Anemia Manifesting as Disseminated Intravascular Coagulation

Pernicious anemia is an autoimmune disorder that is characterized by the presence of autoantibodies to intrinsic factor and parietal cells which results in the inability to absorb vitamin B12. It is the most common manifestation of vitamin B12 deficiency and accounts for 20-50% of cases. Disseminated intravascular coagulation (DIC) is a clinical condition that is a complication of another process which causes the activation of coagulation. A 63-year-old female with a history of hypothyroidism presented with a 1-month history of worsening fatigue, intermittent epigastric pain, nausea, vomiting, and diarrhea. Initial laboratory findings showed severe anemia and macrocytosis with a hemoglobin of 4.3 g/dL and a mean corpuscular volume (MCV) of 138 fL. There was also a significant elevation of the D-dimer, lactate dehydrogenase (LDH), and creatinine. She received three units of packed red blood cells (pRBCs) and fluid resuscitation. A vitamin B12 level was obtained which revealed a severe vitamin B12 deficiency (< 150 pg/mL). Additional workup showed seropositivity for anti-parietal cell antibodies and intrinsic factor blocking antibodies, and an esophagogastroduodenoscopy (EGD) biopsy yielded histologic findings consistent with autoimmune gastritis. She was treated acutely with daily intramuscular B12 injections with improvement in hematologic derangements and symptomatology. Arrested erythropoiesis can lead to apoptosis and the high proliferation of immature erythroblasts results in cells that are more susceptible to impaired deoxyribonucleic acid (DNA) synthesis and results in denatured DNA. Pernicious anemia manifesting as DIC has yet to be described in the literature. Here we describe an interesting case of pernicious anemia manifesting as early DIC resulting from arrest of erythropoiesis evidenced by the international society on thrombosis and hemostasis score of 5, diagnostic for DIC. Early recognition and treatment of this reversible etiology of DIC is essential to the improvement of patient outcomes.

Diagnostic reliability of serum active B12 (holo-transcobalamin) in true evaluation of vitamin B12 deficiency: Relevance in current perspective

OBJECTIVE

Measurement of total vitamin B12 (vit B12) concentration raised concerns over early detection of vit B12 deficiency due to its clinical unreliability. In this present article we aimed to assess the efficacy of holo-transcobolamin (active vit B12) for true evaluation of vit B12 deficiency.

METHODS

This retrospective study included 100 participants referred for vit B12 assay. Serum total vit B12, active vit B12 and homocysteine were estimated.

RESULTS

Our study showed 59% of the total participants with vit B12 deficiency (185 ± 64.62 pg/ml) and 18% with hyper-cobalaminemia (1666.9 ± 367.13 pg/ml) based on their total vit B12 concentrations. A comparative study on total vit B12 and active vit B12 was done which reflected a striking disparity in results. Active vit B12 reported 28.8% patients with vit B12 deficiency (19.8 ± 17.48 pg/ml) and only 16.6% patients with hyper-cobalaminemia (224.14 ± 10 pg/ml). Active vit B12 appeared to be more sensitive (82.35% vs 65%) and specific (46.6% vs. 43.8%) diagnostic marker compared to total vit B12. Pearson Correlation study indicated a strong positive correlation (r = 0.695 at p < 0.01) hence justified use of the two methods.

CONCLUSION

We claim that active vit B12 is a much more reliable biomarker than total vit B12 for early diagnosis of vit B12 deficiency.

Neuromyelitis optica spectrum disease coexisting with subacute combined degeneration: a case report

Background

Subacute combined degeneration (SCD) is a demyelinating disease characterized by vitamin B12 deficiency related segmental degeneration of the dorsal or lateral columns of the spinal cord. However, few cases have been reported as a comorbidity of SCD and neuromyelitis optica spectrum disease (NMOSD).

Case presentation

Herein, we describe a female patient (61-year-old) who had sensory deficits, paresthesia, and weakness of the distal extremities for over 2 months. She then received an initial diagnosis of SCD with typical inverted “V-sigh” hyperintensities over the posterior aspect of the spinal cord in magnetic resonance imaging (MRI - T2-weighted imaging), as well as megaloblastic anaemia in blood examinations. From the past history, there was no evidence of a dietary deficiency or gastric abnormalities. However, traditional treatment with vitamin B12 supplementation was ineffective. Hence, a demyelinating antibody examination showed that she had antibodies targeting aquaporin 4 (AQP4) in both the cerebrospinal fluid and serum, leading to the diagnosis of NMOSD. Her clinical symptoms were obviously improved after treatment with intravenous glucocorticoids.

Conclusion

People who have nutritional deficiency or altered gastrointestinal function are more likely to develop SCD. This case raises the awareness that the poor therapeutic effects of simple vitamin B12 supplementation could be explained by immunoreactions against AQP4. A better recognition will be of great importance for the correct diagnosis of the comorbidity, as well as for essential treatment and even a better prognosis.

Diagnostic value of oral "beefy red" patch combined with fingertip blood mean corpuscular volume in vitamin B12 deficiency

OBJECTIVES

To investigate the diagnostic value of accessible fingertip mean corpuscular volume (MCV) combined with a visible "beefy red" patch in the diagnosis of vitamin B12 (VB12) deficiency in local clinics and hospitals without in-house clinical laboratories, especially in remote areas.

MATERIALS AND METHODS

The medical history data of patients complaining of oral mucosal pain at the Stomatological Hospital of Southern Medical University were reviewed. All included patients underwent fingertip blood routine examination, specific serological test (serum VB12, folic acid, iron, and ferritin), and detailed oral clinical examinations. According to the results of the serum VB12 test patients were divided into case and control groups. In diagnostic test, the diagnostic value of the "beefy red" patch and elevated MCV in VB12 deficiency was evaluated by the receiver operator characteristic curve.

RESULTS

There were more female patients than male patients in the case group (serum VB12 level < 148 pmol/L, n = 81) and control group (serum VB12 level ≥ 148 pmol/L, n = 60), mostly middle-aged and elderly patients. There were no statistical differences in gender and age between the two groups. In the case group, the number of individuals with stomach disease was 13, the number of individuals with "beefy red" patch was 78, the number of individuals with oral ulcer was 29, the number of individuals with "MCV > 100fL" and "folic acid < 15.9 nmol/L" were respectively 68 and 5. All were more than that in control group (P < 0.05). The diagnostic test, "beefy red patch" has high sensitivity (0.963) but low specificity(0.883), "MCV > 100 fL" has high specificity (0.933) but low specificity (0.815), and "MCV > 100 fL combined with beefy red patch" has maximal specificity (0.950), and area under the curve (0.949).

CONCLUSIONS

Visible oral "beefy red" patch combined with accessible fingertip blood MCV could improve the rate of diagnosis in VB12 deficiency, especially in the elderly in local clinics and hospitals without in-house clinical laboratories in China, which is conducive to early disease detection and treatment.

Vitamin B12 levels in patients with retinal vein occlusion and their relation with clinical outcome: a retrospective study

Retinal vein occlusion (RVO) is the second most common retinal vascular disorder, after diabetic retinopathy. Most patients suffering RVO develop some degree of visual loss consequent to retinal complications such as edema and microhemorrhages. Even if some risk factors for RVO have been identified, the clinical outcome of RVO remains highly unpredictable because studies investigating potential prognostic markers for visual improvement are lacking. Cyanocobalamin belongs to the group of B vitamins and plays a role in homocysteine metabolism; however, cyanocobalamin deficiency associates with an increase of some toxic bioproducts involved in endothelial injury and platelet activation independent of homocysteine levels. We retrospectively evaluated the levels of vitamin B12 at diagnosis in 203 patients with RVO, and in a parallel cohort of 120 age- and sex-matched patients without RVO from an internal medicine ward, and correlated them with visual outcome at follow-up (median time 150 days, IQR 30-210). In patients with RVO, vitamin B12 levels at diagnosis were significantly lower than in controls and independently predicted worse clinical outcome at multivariate analysis (OR 3.2; CIs 1.2-8.2; p = 0.015). Our data suggest the opportunity to prospectively evaluate the effect on visual outcome of cyanocobalamin supplementation in RVO patients.

Structural and Functional Brain Changes Associated with Vitamin B12 Deficiency using Magnetic Resonance Imaging: A systematic review and meta-analysis

AIM

This review was conducted to assess the structural and functional brain changes associated with vitamin B12 deficiency in different age groups using MRI.

METHODS

PubMed, Embase, Medline, CINAHL, Scopus, Web of Science, and Google Scholar were searched for magnetic resonance imaging [MRI] studies that explored structural and functional brain changes associated with vitamin B12 deficiency in different age groups. The inclusion criteria were as follows: [1] the population consisted of people and not animals; [2] patients with known B12 deficiency; [3] English publications; [3] at least one of the following brain MRI techniques had been employed: VBM, DWI, DTI, fMRI, or rs-fMRI. However, case reports, systematic reviews and meta-analysis were excluded.

RESULTS

Twelve articles met the inclusion criteria. The results of my review show a connection between vitamin B12 deficiency and abnormal structural and functional brain changes in several brain regions. These changes were observed in different age groups ranging from a mean age of seven years to a mean age in the 70s. The results also highlight the association between brain changes and cognitive decline among affected subjects. Improvements in damaged brain regions post-vitamin B12 treatment were also studied.

CONCLUSION

Structural and functional brain damage was found to be associated with vitamin B12 deficiency in all age groups. Vitamin B12 treatment may lead to partial or complete structural and/or functional recovery, as well as a cognitive recovery.

Neuropsychiatric manifestations in vitamin B12 deficiency

Vitamin B12 deficiency can have distressing neuropsychiatric symptoms. It can have an etiological role in clinical presentations like depression, anxiety, psychosis, dementia, and delirium, requiring screening of at-risk populations. Few mechanisms that underlie the neuropsychiatric manifestations of B12 deficiency include alteration in one-carbon metabolism, genetic vulnerability, and alteration in folate metabolism. Maintaining a high serum B12 level in elderly can be protective against Alzheimer's disease (AD). In an established AD, its deficiency is associated with higher cognitive decline and risk for delirium. The other mental changes associated with B12 deficiency include apathy, agitation, impaired concentration, insomnia, persecutory delusions, auditory and visual hallucinations, and disorganized thought-process. Besides serum vitamin B12, plasma methylmalonic acid (MMA) and homocysteine helps in diagnosis. The chapter focuses on early recognition and effective treatment of these neuropsychiatric manifestations of vitamin B12 deficiency.

Vitamin B12 (Cobalamin) Deficiency in Overt and Subclinical Primary Hypothyroidism

Background:

B12 (cobalamin) deficiency has been reported in hypothyroid patients with variable prevalence rates thus routine screening of hypothyroid patients was recommended by some and discouraged by others. We aimed to assess the prevalence of B12 deficiency among hypothyroid patients and to evaluate for pernicious anemia and celiac disease as etiologies.

Methods:

A total 133 patients were included. Thyroid hormones and thyroid peroxidase (TPO) autoantibodies were measured. Serum B12 was measured and if deficient, intrinsic factor antibodies (IFAB) and tissue transglutaminase (tTG) antibodies were evaluated.

Results:

Our study included 45 patients with overt hypothyroidism (OH), 48 patients with subclinical hypothyroidism (SCH), and 40 patients as controls. Mean age was 34.3 years and 82% were females. TPO antibodies were positive in 73.5% of OH and 51.1% of SCH patients. B12 deficiency was detected in 33.3%, 47.9%, and 37.5% of OH, SCH, and controls, respectively with no significant difference (P = .334). Borderline-to-low B12 level was more prevalent in the OH and the SCH groups compared to controls (68.9%, 85.4%, and 57.5%, respectively; P = .014). Among B12-deficient hypothyroid patients, 7.5% had positive IFAB and 13.3% had positive tTG antibodies. We did not find a significant association of TPO positivity and B12 deficiency (OR, 0.69; 95% CI 0.3-1.57; P = .147).

Conclusion:

We did not find a higher prevalence of B12 deficiency among hypothyroid patients nor an association with TPO positivity. Borderline B12 levels were more prevalent among hypothyroid patients.

Early autoimmune gastritis presenting with a normal endoscopic appearance

This report describes a patient with early-stage autoimmune gastritis (AIG) presenting with a normal endoscopic appearance. A 66-year-old man with autoimmune thyroiditis was suspected of having AIG because of a previous history of vitamin B12 deficiency when receiving steroid therapy for interstitial pneumonia 5 years earlier. At presentation, he tested positive for anti-parietal cell antibody (1:320) and anti-intrinsic factor antibody, but not for vitamin B12 deficiency. His gastrin level was elevated (338 pg/mL), but his pepsinogen (PG) I level (56.1 ng/mL) and PGI/PGII ratio (7.6) were normal. Endoscopically, neither atrophic nor inflammatory changes were observed. Histopathologic examination, however, showed mild atrophic changes with dense lymphocytic infiltration in the deep lamina propria and focal destruction of parietal cells in the greater curvature of the corpus. PGI-positive/MUC6-positive pseudo-pyloric metaplasia was observed in the area from which H⁺/K⁺-ATPase-positive parietal cells had disappeared. Chromogranin A immunostaining showed linear hyperplasia of enterochromaffin-like cells. By contrast, atrophic changes were not evident in the lesser curvature of the corpus, except for mild lymphocytic infiltration around and into the fundic glands. These serological and histopathological findings suggested that the patient had early-stage AIG with a normal endoscopic appearance.

Evaluation of the response to vitamin B12 supplementation in patients with atrophy in sleeve gastrectomy materials

OBJECTIVE

Vitamin B12 deficiency can be seen in the cases with sleeve gastrectomy. Because the chief factor in vitamin B12 deficiency is gastric atrophy, we aimed to evaluate the effect of atrophy on postoperative vitamin B12 levels in patients who underwent sleeve gastrectomy.

MATERIAL AND METHODS

Sixty patients were included in this study. Vitamin B12 levels were compared with presence of atrophy before the operation and after vitamin B12 supplementation.

RESULTS

Atrophy was observed in 37 (61.7%) of the cases; 23 (38.3%) patients had no atrophy. There was a statistically significant difference between the presence of atrophy and vitamin B12 levels (p = 0.024). Despite vitamin B12 support, there were statistically significant low vitamin B12 levels after the operation in female patients having atrophy (p = 0.023). The same significance was not observed in males (p = 0.480).

CONCLUSION

Vitamin B12 deficiency following obesity surgery is a condition that must be monitored and prevented. We found that histopathologically confirmed atrophy had an adverse effect on postoperative vitamin B12 levels. These findings can be a guide for the clinicians in the management of these cases.

Micronutrient's deficiency in India: a systematic review and meta-analysis

India is coming to grips with a stage of nutrition transition. According to the Food Safety and Standards Authority of India (FSSAI), preventable micronutrient deficiency is arising public health precedence in India. However, the foremost public health concern is the lack of national prevalence data. The present study was carried out to estimate the pooled age-wise prevalence of six preventable micronutrient deficiencies (vitamin A, vitamin B₁₂, vitamin D, iron, iodine and folic acid) in India. A systematic review was carried out on PubMed and Global Index Medicus databases using the Boolean search strategy. Statistical analyses were done using R software, version 3.6. 2. PRISMA guidelines were strictly adhered to during the review. A preliminary literature search yielded 4302 articles; however, 270 original research articles were found eligible to be included in quantitative synthesis. The estimated overall prevalence was 17 % [95 % confidence interval (CI) 0⋅07, 0⋅26] for iodine deficiency, 37 % (95 % CI 0⋅27, 0⋅46) for folic acid deficiency, 54 % (95 % CI 0⋅49, 0⋅59) for iron deficiency, 53 % (95 % CI 0⋅41, 0⋅64) for vitamin B₁₂ deficiency, 19 % (95 % CI 0⋅09, 0⋅29) for vitamin A deficiency and 61 % (95 % CI 0⋅07, 0⋅26) for vitamin D with high heterogeneity. We classified the population into infants (0–5 years), adolescents (<18 years), adults (>18 years) and pregnant women. Iron deficiency was most prevalent (61 %) in pregnant women. The results of the present study reinforce the data on micronutrient deficiency in India and warrant the immediate need for further active public health interventions to address these deficiencies. The study is registered with PROSPERO (CRD42020205043).

Impact of Correcting Nutritional Deficiency Anemias in the Elderly on Hospitalizations, Falls, and Mortalities

Background

The incidence and prevalence of anemia increase with age, particularly in adults older than 65 years, and it is associated with a number of adverse health outcomes (AHO), particularly hospitalizations, falls and mortalities. Given that approximately one-third of these anemias are due to reversible causes, we studied whether the treatment of nutritional deficiency anemia (NDA), namely iron deficiency anemia (IDA), cobalamin deficiency anemia (CDA), and folate deficiency anemia (FDA), improves AHO; and explored whether each NDA had different AHO.

Methods

We reviewed electronic medical records of our internal medicine office patients aged 65 years or older, who had a diagnosis of anemia in a non-acute setting.

Results

Total 600 patients were included. Mean age was 75.2 years. Thirty-one point three percent had NDA (CDA 15.3%, IDA 12.3%, FDA 3.7%); and 68.7% had other anemias whom we categorized as non-nutritional deficiency anemias (NNDA), which included anemia of chronic disease (11.2%), myelodysplastic syndrome (6.2%), renal insufficiency anemia (5.7%) and unexplained anemia (45.6%). Even after adequate treatment, IDA group had significantly more hospitalizations (median, 25th - 75th: 2 (0 - 4) vs. 0 (0 - 1), P < 0.001), falls (median, 25th - 75th: 1 (0 - 3) vs. 0 (0 - 1), P < 0.001) and mortalities (10.8% vs. 3.4%, P = 0.011); CDA group had significantly more hospitalizations (median, 25th - 75th: 1 (0 - 2) vs. 0 (0 - 1), P = 0.007), but no difference in falls (median, 25th - 75th: 0 (0 - 1) vs. 0 (0 - 1), P = 0.171) and mortalities (7.6% vs. 3.4%, P = 0.083); and FDA group had significantly more hospitalizations (median, 25th - 75th: 1 (0 - 2) vs. 0 (0 - 1), P = 0.001), but no difference in falls (median, 25th - 75th: 0 (0 - 1) vs. 0 (0 - 1), P = 0.615) and mortalities (4.5% vs. 3.4%, P = 0.550), compared to the NNDA group. Age, Black race, higher number of comorbidities, presence of malignancy and use of direct oral anticoagulants were associated with increased odds of AHO in patients with NDA.

Conclusions

Compared to the patients with NNDA, patients with IDA had more hospitalizations, falls and mortalities even after adequate treatment; while patients with CDA and FDA had only more hospitalizations. Adequate treatment mitigated falls and mortalities in elderly patients with CDA and FDA.

Higher gastric parietal cell antibody titer significantly increases the frequencies of macrocytosis, serum vitamin B12 deficiency, and hyperhomocysteinemia in patients with burning mouth syndrome

BACKGROUND/PURPOSE

Our previous study found 109 gastric parietal cell antibody (GPCA)-positive burning mouth syndrome (BMS) patients (so-called GPCA⁺BMS patients in this study) in a group of 884 BMS patients. This study evaluated whether high-titer (GPCA titer ≥ 160) GPCA⁺BMS patients had greater frequencies of macrocytosis, anemia, serum iron and vitamin B12 deficiencies, and hyperhomocysteinemia than low-titer (GPCA titer < 160) GPCA⁺BMS patients or 442 healthy control subjects.

MATERIALS AND METHODS

Complete blood count, serum iron, vitamin B12, folic acid, homocysteine, and GPCA levels in 42 high-titer GPCA⁺BMS patients, 67 low-titer GPCA⁺BMS patients, and 442 healthy control subjects were measured and compared.

RESULTS

We found that 33.3%, 38.1%, 19.0%, 33.3%, 2.4%, and 57.1% of 42 high-titer GPCA⁺BMS patients and 10.4%, 25.4%, 14.9%, 6.0%, 1.5%, and 11.9% of 67 low-titer GPCA⁺BMS patients were diagnosed as having macrocytosis, blood hemoglobin, iron, vitamin B12, and folic acid deficiencies, and hyperhomocysteinemia, respectively. Moreover, both 42 high-titer and 67 low-titer GPCA⁺BMS patients had significantly greater frequencies of macrocytosis, blood hemoglobin, serum iron and vitamin B12 deficiencies, and hyperhomocysteinemia than 442 healthy control subjects (all P-values < 0.001). In addition, 42 high-titer GPCA⁺BMS patients also had greater frequencies of macrocytosis, serum vitamin B12 deficiency, and hyperhomocysteinemia than 67 low-titer GPCA⁺BMS patients (all P-values < 0.01).

CONCLUSION

The high-titer GPCA⁺BMS patients have significantly greater frequencies of macrocytosis, anemia, serum iron and vitamin B12 deficiencies, and hyperhomocysteinemia than healthy control subjects and significantly greater frequencies of macrocytosis, serum vitamin B12 deficiency, and hyperhomocysteinemia than low-titer GPCA⁺BMS patients.

Anemia, hematinic deficiencies, hyperhomocysteinemia, and gastric parietal cell antibody positivity in burning mouth syndrome patients with normocytosis

Background/Purpose

Normocytosis is defined as having the mean corpuscular volume (MCV) between 80 fL and 99.9 fL. This study evaluated whether 770 burning mouth syndrome (BMS) patients with normocytosis (so-called normocytosis/BMS patients) had significantly higher frequencies of anemia, hematinic deficiencies, hyperhomocysteinemia, and serum gastric parietal cell antibody (GPCA) positivity than 442 healthy control subjects or 884 BMS patients.

Materials and methods

Complete blood count, serum iron, vitamin B12, folic acid, homocysteine, and GPCA levels in 884 BMS patients (including 770 normocytosis/BMS patients) and 442 healthy control subjects were measured and compared.

Results

We found that 12.3%, 13.2%, 2.2%, 2.3%, 17.3%, and 10.5% of 770 normocytosis/BMS patients had blood hemoglobin (Hb), iron, vitamin B12, and folic acid deficiencies, hyperhomocysteinemia, and serum GPCA positivity, respectively. Furthermore, 770 normocytosis/BMS patients had significantly higher frequencies of blood Hb, iron, vitamin B12, and folic acid deficiencies, hyperhomocysteinemia, and serum GPCA positivity than 442 healthy control subjects (all P-values < 0.005). On the contrary, 770 normocytosis/BMS patients had significantly lower frequencies of blood Hb and vitamin B12 deficiencies than overall 884 BMS patients (both P-values < 0.01).

Conclusion

We conclude that there are significantly higher frequencies of anemia, serum iron, vitamin B12, and folic acid deficiencies, hyperhomocysteinemia, and serum GPCA positivity in normocytosis/BMS patients than in healthy control subjects. On the contrary, normocytosis/BMS patients do have significantly lower frequencies of blood Hb and vitamin B12 deficiencies than overall BMS patients.

Prevalence of Vitamin B12 deficiency in elderly population (>60 years) presenting with dementia to outpatient department

BACKGROUND

Vitamin B12 deficiency is an easily treatable cause of reversible dementia. It is likely to be more common in Indian population due to traditionally vegetarian culture. This study was conducted to estimate the prevalence of Vitamin B12 deficiency in elderly patients (>60 years) with dementia attending outpatient department.

METHODS

This study was conducted in two phases. The first phase was a cross sectional observational study to estimate the prevalence of Vitamin B12 deficiency in the elderly population with dementia. The second phase was a pilot study done in subjects with Vitamin B12 deficiency to assess the change in cognition following Vitamin B12 supplementation.

RESULTS

Out of 2920 study eligible subjects, 200 were diagnosed as dementia with Mini Mental Status Examination (MMSE) score of ≤ 24. Vitamin B12 deficiency was seen in 7.5% of patients. Vitamin B12 deficiency was associated with shorter and more severe dementia. Macrocytosis was more common in Vitamin B12 deficiency (p value < 0.001) where as vegetarian diet did not show significant correlation (p value 0.69). There was significant improvement in the median MMSE score in the intervention group with increase in MMSE by 2 points at 6-8 weeks and 3 points at 12 weeks (p value 0.009 and 0.003 by Mann Whitney test).

CONCLUSION

Prevalence of Vitamin B12 deficiency in dementia was 7.5%. It was associated with macrocytosis, shorter duration and more severe dementia. There was a significant improvement in median MMSE score at 6 weeks and 12 weeks following Vitamin B12 supplementation.

Reference intervals for plasma vitamin B12 and plasma/serum methylmalonic acid in Danish children, adults and elderly

BACKGROUND

Plasma/serum vitamin B12 (B12) is often used to screen for B12 deficiency complemented with analysis of methylmalonic acid (MMA) in case of low B12. The concentration of both analytes likely depends on age, and we, therefore, aimed at establishing 95% age-adjusted reference intervals (RIs) for plasma B12 and serum/plasma MMA in the Danish population.

METHODS

We collected and analysed blood samples from healthy children, adults, and elderly individuals and extracted routine clinical B12 and MMA results to establish RIs. We also evaluated the association between matching B12 and MMA results.

RESULTS

We suggest the following RIs for plasma B12 and plasma/serum MMA, respectively. 0-<1 year: 180-1400 pmol/L, 0.10-1.25 µmol/L; 1-<11 years: 260-1200 pmol/L, 0.10-0.30 µmol/L; 12-<18 years: 200-800 pmol/L, 0.10-0.35 µmol/L; 18-<65 years: 200-600 pmol/L, 0.10-0.40 µmol/L; 65 + years: 200-600 pmol/L, 0.12-0.46 µmol/L. Finally, the proportion of patients with elevated MMA differed between age groups independently of B12 and was highest in children.

CONCLUSION

We propose new age-adjusted RIs for B12 and MMA and suggest that age-dependent cut-off values should be implemented if plasma B12 is used to screen for B12 deficiency.

The dangers of recreational inhalation of nitrous oxide

Nitrous oxide, also known as 'laughing gas', is one of the most widely used recreational drugs among teenagers in the UK. Copious inhalation of nitrous oxide may increase intra-alveolar pressure, resulting in barotrauma secondary to alveolar rupture. Pneumomediastinum and subcutaneous emphysema are common clinical findings in nitrous oxide-associated barotrauma. Prolonged nitrous oxide misuse may inactivate vitamin B₁₂ through the alteration of its metabolism, causing demyelination of the central and peripheral nervous system. A spectrum of neurological manifestations has been reported, including peripheral neuropathy, myelopathy and subacute combined degeneration of the spinal cord. Medical therapies and psychosocial interventions aiming at nitrous oxide cessation are important treatment steps to achieve partial or complete recovery from the adverse effects associated with inhalation of nitrous oxide.

Acute cerebellar ataxia as the first manifestation of Imerslund-Gräsbeck syndrome

Imerslund-Gräsbeck syndrome is a rare condition caused by vitamin B12 deficiency and proteinuria. In this article, we reported the case of a 10-year-old girl with imbalance and urinary incontinence. The case had cerebellar ataxia as the primary manifestation. The disequilibrium had progressed gradually within three weeks and was consistent with the symptoms of cerebellar involvement and urinary incontinence. Brain and cervico-thoraco-lumbar magnetic resonance imaging were normal. The patient had elevated lactate dehydrogenase (LDH=4775), in addition to macrocytic anemia, on laboratory examinations; thus, the possibility of malignancy was raised. Then, bone marrow aspiration was performed, showing hypercellular marrow with megaloblastic changes. This finding proved megaloblastic anemia. Regarding the low prevalence of vitamin B12 deficiency in healthy individuals, extensive studies were performed to find out the cause. The serum level of vitamin B12 was found to be lower than the normal range. Although urinalysis revealed significant proteinuria, further nephrological investigations did not indicate any abnormalities. No evidence of serious problems was observed in the gastrointestinal tract study, and metabolic studies were normal. Finally, based on the obtained data, Imerslund-Gräsbeck syndrome was recognized. Patient was treated by vitamin B12 injection, leading to improved balance, and in one-month follow-up, she was able to walk independently, and the cerebellar symptoms had greatly disappeared; however, proteinuria persisted.

Prevalence and Disparities in Folate and Vitamin B12 Deficiency Among Preschool Children in Guatemala

BACKGROUND AND OBJECTIVE

Folate and vitamin B12 deficiencies can impair proper growth and brain development in children. Data on the folate and vitamin B12 status of children aged 6-59 months in Guatemala are scarce. Identification of factors associated with higher prevalence of these micronutrient deficiencies within the population is needed for national and regional policymakers.

OBJECTIVE

To describe national and regional post-fortification folate and vitamin B12 status of children aged 6-59 months in Guatemala.

METHODS

A multistage, cluster probability study was carried out with national and regional representation of children aged 6-59 months. Demographic and health information was collected for 1246 preschool children, but blood samples for red blood cell (RBC) folate and vitamin B12 were collected and analyzed for 1,245 and 1143 preschool children, respectively. We used the following deficiency criteria as cutoff points for the analyses: < 305 nmol/L for RBC folate, < 148 pmol/L for vitamin B12 deficiency, and 148-221 pmol/L for marginal vitamin B12 deficiency. Prevalence of RBC folate deficiency and vitamin B12 deficiency and marginal deficiency were estimated. Prevalence risk ratios of RBC folate and vitamin B12 deficiency were estimated comparing subpopulations of interest.

RESULTS

The national prevalence estimates of RBC folate deficiency among children was 33.5% [95% CI 29.1, 38.3]. The prevalence of RBC folate deficiency showed wide variation by age (20.3-46.6%) and was significantly higher among children 6-11 months and 12-23 months (46.6 and 37.0%, respectively), compared to older children aged 48-59 months (20.3%). RBC folate deficiency also varied widely by household wealth index (22.6-42.0%) and geographic region (27.2-46.7%) though the differences were not statistically significant. The national geometric mean for RBC folate concentrations was 354.2 nmol/L. The national prevalences of vitamin B12 deficiency and marginal deficiency among children were 22.5% [95% CI 18.2, 27.5] and 27.5% [95% CI 23.7, 31.7], respectively. The prevalence of vitamin B12 deficiency was significantly higher among indigenous children than among non-indigenous children (34.5% vs. 13.1%, aPRR 2.1 95% CI 1.4, 3.0). The prevalence of vitamin B12 deficiency also significantly varied between the highest and lowest household wealth index (34.3 and 6.0%, respectively). The national geometric mean for vitamin B12 concentrations was 235.1 pmol/L. The geometric means of folate and B12 concentrations were significantly lower among children who were younger, had a lower household wealth index, and were indigenous (for vitamin B12 only). Folate and vitamin B12 concentrations showed wide variation by region (not statistically significant), and the Petén and Norte regions showed the lowest RBC folate and vitamin B12 concentrations, respectively.

CONCLUSIONS

In this study, a third of all children had RBC folate deficiency and half were vitamin B12 deficient. Folate deficiency was more common in younger children and vitamin B12 deficiency was more common in indigenous children and those from the poorest families. These findings suggest gaps in the coverage of fortification and the need for additional implementation strategies to address these gaps in coverage to help safeguard the health of Guatemalan children.

Association of vitamin B12 deficiency with metformin use in patients with type 2 diabetes treated in the largest tertiary care hospital in Qatar

BACKGROUND

Data on the effect of metformin on serum vitamin B12 (VitB12) level in patients with type 2 diabetes mellitus (T2DM) in Qatar are limited; therefore, we aimed to assess the prevalence of VitB12 deficiency and its related factors among patients with tbl2DM treated with metformin at Hamad General Hospital in Doha, Qatar, from January 1, 2017, to December 31, 2017.

METHODS

This cross-sectional analytical study involved patients with tbl2DM aged ≥ 18 years who used metformin for at least 3 months. The serum VitB12 was quantified on a chemiluminescent enzyme immunoassay analyzer using Cobas e 801 module, Roche, and VitB12 deficiency was defined as serum VitB12 level of ≤ 145 pmol/L. All data were obtained from the patients' electronic medical records.

RESULTS

The study recruited 3124 eligible patients with tbl2DM. The overall prevalence of metformin-associated VitB12 deficiency was 30.7% [95% confidence of interval, 0.290-0.323]. A significant difference exists in the median VitB12 levels between the VitB12-normal and VitB12-deficient groups [129 vs. 286; p < 0.001]. Compared with the VitB12-normal group, the VitB12-deficient group had higher mean body mass index (BMI) (p < 0.001) and consumed higher doses of metformin (p = 0.001). They also more often used sulfonylurea (p = 0.004), dipeptidyl peptidase-4 inhibitor (p < 0.001), thiazolidinediones (p < 0.001), glucagon-like peptide 1 [GLP-1] receptor agonists (p < 0.001), alpha-glucosidase inhibitor (p < 0.001), and H2 blocker/proton pump inhibitors [PPI] (p < 0.001) than the VitB12-normal group. Moreover, the VitB12-normal group consumed more calcium supplements (p < 0.001) than the VitB12-deficient group. In the multivariate analysis, independent risk factors for metformin-associated VitB12 deficiency in patients with tbl2DM include high daily dose of metformin >2000 mg, male gender, high BMI, smoking, sulfonylurea, dipeptidyl peptidase-4 inhibitor, H2 blockers/PPI, low fasting blood glucose, and low hemoglobin.

CONCLUSION

This study showed a high prevalence of VitB12 deficiency in patients with tbl2DM taking metformin and a significant negative correlation between the daily dose of metformin and serum VitB12 level. Therefore, regular screening for serum VitB12 is necessary in patients with tbl2DM on metformin treatment, especially those who have the abovementioned risk factors.

Improvement in vitamin B12 status of Wistar rats by supplementing the diet with Chlorella vulgaris biomass

The sources of bioavailable vitamin B₁₂ are limited, and most of them are animal-derived. Chlorella vulgaris, a freshwater microalga, is known for immune system boosting, nutraceutical properties and presence of a natural form of vitamin B₁₂. The present study focused on the in vivo evaluation of the Chlorella biomass as a source of bioavailable vitamin B₁₂ to alleviate the vitamin B₁₂ deficiency status of Wistar rats. Experimental animals were evaluated for the vitamin B₁₂ deficiency-related circulatory marker (serum vitamin B₁₂) and functional markers (plasma homocysteine and urinary methylmalonic acid), haematological and histological changes. The results showed that an increase of 2.4-fold in urinary methylmalonic acid (13.01 ± 0.89 µmoles moles of creatinine^-1), 2.6-fold in plasma homocysteine (17.18 ± 3.57 µmole L^-1), and 48% decrease in serum vitamin B₁₂ levels (252.69 ± 1.46 pg mL^-1) in vitamin B₁₂ deficient group compared to control animals. The Chlorella biomass supplementation in the diet led to the restoration of the functional and circulatory markers, hematological parameters, and vitamin B₁₂ content of kidney and liver to control levels. The Chlorella biomass supplementation increased the erythrocyte precursors and MAST cells in the bone marrow and also normalized the histological features of kidney, liver, and lung tissues. The results suggest that the vitamin B₁₂ from the Chlorella biomass was bioavailable and facilitated the improvement of vitamin B₁₂ status in deficient rats.

Severe Vitamin B12 Deficiency Mimicking Microangiopathic Hemolytic Anemia

Most individuals with vitamin B12 deficiency present with anemia, fatigue, and neurologic disturbances such as paresthesia and loss of sensory function if chronic. However, in severe states, it may manifest as hemolytic anemia, thrombocytopenia, schistocytosis, elevated lactate dehydrogenase, and low reticulocyte production. This phenomenon is known as pseudo-thrombotic microangiopathy (TMA), and is most commonly due to pernicious anemia. The overlap in clinical presentation with primary TMA creates a challenge in the diagnosis and management of pseudo-TMA. Primary TMA, particularly thrombotic thrombocytopenic purpura, is emergently managed with plasma exchange and may require admission to an intensive care unit due to high risk of mortality. In contrast, pseudo-TMA does not respond to plasma exchange and instead is treated with vitamin B12 supplementation. Patients with this atypical presentation of B12 deficiency may receive unnecessary, costly, and potentially harmful therapy. We present the case of a patient with pseudo-TMA in the setting of pernicious anemia.

Anemia, hematinic deficiencies, hyperhomocysteinemia, and gastric parietal cell antibody positivity in burning mouth syndrome patients with macrocytosis

Background/purpose

Macrocytosis is defined as having the mean corpuscular volume (MCV) ≥ 100 fL. This study evaluated whether 46 burning mouth syndrome (BMS) patients with macrocytosis had significantly higher frequencies of anemia, hematinic deficiencies, hyperhomocysteinemia, and serum gastric parietal cell antibody (GPCA) positivity than 442 healthy control subjects or 884 BMS patients.

Materials and methods

Complete blood count, serum iron, vitamin B12, folic acid, homocysteine, and GPCA levels in 46 BMS patients with macrocytosis, 884 BMS patients, and 442 healthy control subjects were measured and compared.

Results

We found that 65.2%, 23.9%, 47.8%, 0.0%, 60.9%, and 45.7% of 46 BMS patients with macrocytosis were diagnosed as having blood hemoglobin, iron, vitamin B12, and folic acid deficiencies, hyperhomocysteinemia, and serum GPCA positivity, respectively. Moreover, 46 BMS patients with macrocytosis had significantly higher frequencies of blood hemoglobin and serum vitamin B12 deficiencies, hyperhomocysteinemia, and serum GPCA positivity than 442 healthy control subjects or 884 BMS patients (all P-values < 0.001). In addition, 46 BMS patients with macrocytosis also had a significantly higher frequency of serum iron deficiency than 442 healthy control subjects (P < 0.001). Pernicious anemia was found in 15 BMS patients with macrocytosis.

Conclusion

There are significantly higher frequencies of anemia and serum iron and vitamin B12 deficiencies, hyperhomocysteinemia, and serum GPCA positivity in BMS patients with macrocytosis than in healthy control subjects. BMS patients with macrocytosis also have significantly higher frequencies of anemia, serum vitamin B12 deficiency, hyperhomocysteinemia, and serum GPCA positivity than BMS patients.

Anemia, hematinic deficiencies, and hyperhomocysteinemia in serum gastric parietal cell antibody-positive burning mouth syndrome patients without serum thyroid autoantibodies

Background/purpose

Our previous study found that 70 of 884 burning mouth syndrome (BMS) patients have serum gastric parietal cell antibody (GPCA) positivity but without thyroglobulin antibody (TGA) and thyroid microsomal antibody (TMA) (so-called GPCA⁺TGAˉTMAˉBMS patients). This study assessed whether these 70 GPCA⁺TGAˉTMAˉBMS patients had significantly higher frequencies of macrocytosis, anemia, hematinic deficiencies, and hyperhomocysteinemia than 553 GPCA-negative, TGA-negative, and TMA-negative BMS (GPCAˉTGAˉTMAˉBMS) patients or 442 healthy control subjects.

Materials and methods

Complete blood count, serum iron, vitamin B12, folic acid, homocysteine, GPCA, TGA, and TMA levels in 70 GPCA⁺TGAˉTMAˉBMS patients, 553 GPCAˉTGAˉTMAˉBMS patients, and 442 healthy control subjects were measured and compared.

Results

We found that 15.7%, 28.6%, 20.0%, 11.4%, 2.9%, and 25.7% of 70 GPCA⁺TGAˉTMAˉBMS patients and 3.8%, 17.7%, 15.9%, 3.8%, 2.7%, and 20.1% of 553 GPCAˉTGAˉTMAˉBMS patients had macrocytosis, blood hemoglobin, iron, vitamin B12, and folic acid deficiencies, and hyperhomocysteinemia, respectively. Moreover, both 70 GPCA⁺TGAˉTMAˉBMS patients and 553 GPCAˉTGAˉTMAˉBMS patients had significantly greater frequencies of macrocytosis, blood hemoglobin, serum iron, vitamin B12, and folic acid deficiencies, and hyperhomocysteinemia than 442 healthy control subjects (all P-values < 0.05). In addition, 70 GPCA⁺TGAˉTMAˉBMS patients also had greater frequencies of macrocytosis, anemia, serum vitamin B12 deficiency, and hyperhomocysteinemia than 553 GPCAˉTGAˉTMAˉBMS patients (all P-values < 0.05).

Conclusion

The GPCA ⁺ TGAˉTMAˉBMS patients have significantly greater frequencies of macrocytosis, anemia, serum iron, vitamin B12, and folic acid deficiencies, and hyperhomocysteinemia than healthy control subjects and significantly greater frequencies of macrocytosis, anemia, serum vitamin B12 deficiency, and hyperhomocysteinemia than GPCAˉTGAˉTMAˉBMS patients.

Etiological causes of pancytopenia: A report of 137 cases

OBJECTIVE

The aim of this study is to evaluate the etiological causes of pancytopenia in patients who were admitted to the hematology ward due to pancytopenia.

MATERIALS AND METHODS

All patients who were admitted to the hematology ward of Ministry of Health Istanbul Training and Research Hospital due to pancytopenia between 2013 and 2015 were retrospectively evaluated regarding etiological causes.

RESULTS

A total of 137 patients was evaluated. The etiological causes of pancytopenia were recorded as Vitamin B12 deficiency (n: 24; 17%), chronic liver disease (n: 21; 15%), malignancy (n: 19; 13%), myelodysplastic syndrome (n: 18; 13%), aplastic anemia (n: 11; 8%), rheumatic diseases (n: 7; 5%), and endocrine causes (n: 3; 2%).

CONCLUSION

The etiological causes of pancytopenia vary depends on patients' age, gender, country, and other conditions. Vitamin B12 deficiency is the most common treatable cause of pancytopenia. Most of the etiological causes could be diagnosed with laboratory analysis and radiological imagings, without the need of a bone marrow examination.

Long-term metformin therapy and vitamin B12 deficiency: An association to bear in mind

To date, metformin remains the first-line oral glucose-lowering drug used for the treatment of type 2 diabetes thanks to its well-established long-term safety and efficacy profile. Indeed, metformin is the most widely used oral insulin-sensitizing agent, being prescribed to more than 100 million people worldwide, including patients with prediabetes, insulin resistance, and polycystic ovary syndrome. However, over the last decades several observational studies and meta-analyses have reported a significant association between long-term metformin therapy and an increased prevalence of vitamin B12 deficiency. Of note, evidence suggests that long-term and high-dose metformin therapy impairs vitamin B12 status. Vitamin B12 (also referred to as cobalamin) is a water-soluble vitamin that is mainly obtained from animal-sourced foods. At the cellular level, vitamin B12 acts as a cofactor for enzymes that play a critical role in DNA synthesis and neuroprotection. Thus, vitamin B12 deficiency can lead to a number of clinical consequences that include hematologic abnormalities (e.g., megaloblastic anemia and formation of hypersegmented neutrophils), progressive axonal demyelination and peripheral neuropathy. Nevertheless, no definite guidelines are currently available for vitamin B12 deficiency screening in patients on metformin therapy, and vitamin B12 deficiency remains frequently unrecognized in such individuals. Therefore, in this "field of vision" article we propose a list of criteria for a cost-effective vitamin B12 deficiency screening in metformin-treated patients, which could serve as a practical guide for identifying individuals at high risk for this condition. Moreover, we discuss additional relevant topics related to this field, including: (1) The lack of consensus about the exact definition of vitamin B12 deficiency; (2) The definition of reliable biomarkers of vitamin B12 status; (3) Causes of vitamin B12 deficiency other than metformin therapy that should be identified promptly in metformin-treated patients for a proper differential diagnosis; and (4) Potential pathophysiological mechanisms underlying metformin-induced vitamin B12 deficiency. Finally, we briefly review basic concepts related to vitamin B12 supplementation for the treatment of vitamin B12 deficiency, particularly when this condition is induced by metformin.