Methylmalonic Acid Concentrations Research Articles

Intranasal vitamin B12 administration in elderly patients: A randomized controlled comparison of two dosage regimens.

Vitamin B12 deficiency is common in the elderly population. Standard treatment via intramuscular injections, however, has several disadvantages. Safer and more convenient dosage forms such as intranasal are therefore being explored. This study compares the effects of two intranasal vitamin B12 dosage regimens in elderly vitamin B12-deficient patients. Sixty patients ≥65 years were randomly assigned to either a loading dose (daily administration for 14 days followed by weekly administration) or a no loading dose (administration every 3 days) regimen for 90 days. Each dose contained 1000 μg cobalamin. Total vitamin B12, holotranscoblamin (holoTC), methylmalonic acid (MMA) and total homocysteine (tHcy) levels in serum were measured on days 0, 7, 14, 30, 60 and 90. Both dosage regimens resulted in a rapid increase of vitamin B12 and holoTC concentrations and normalization of initial high, MMA and tHcy concentrations. The loading dose regimen resulted in the fastest and greatest increase to a median vitamin B12 of 1090 pmol/L (reference 350-650 pmol/L) concentration after 14 days. Following weekly administration, B12 rapidly decreased to a median concentration of 530 pmol/L after 90 days. The no loading dose regimen resulted in a steady increase to a median vitamin B12 of 717 pmol/L after 90 days. Intranasal vitamin B12 administration is an effective and suitable way to replenish and sustain vitamin B12 levels in elderly patients.

On the Relationship between MMA Levels in Blood Products and Donor Sex, Age, and Donation Frequency.

As the aging process accelerates, the age structure of blood donors turns to older and even aged groups. Methylmalonic acid (MMA), a byproduct of propionate metabolism, may be upregulated in the serum of older adults. As a mediator of chronic disease and tumor progression, the MMA content in blood products has become the focus of research. Absolute concentrations of MMA in blood products were determined based on the liquid chromatography-tandem mass spectrometry, so as to analyze how they were affected by donors' age, sex, and frequency of blood donation. The MMA content in leukocyte-depleted suspended red blood cell (lds-RBC) was significantly higher than that in fresh plasma (p<0.0001). The MMA content among five age groups showed no difference in either fresh plasma or lds-RBCs. The MMA content in fresh plasma was similar in the parameters of the sex, whereas that in lds-RBCs was higher in males than that in females (p=0.035). There were no significant differences in MMA content when it comes to different frequencies of blood donors in either fresh plasma or lds-RBCs. Additionally, there was no significant difference or clear trend in the rate of elevated plasma MMA levels among different sexes, age groups, and blood donation frequency groups. MMA in the blood products from donors in China does not compromise the safety of blood transfusions for cancer patients. Nevertheless, there is a need to focus on MMA levels in Chinese and to develop race-specific and age-specific normal reference ranges.

Aging-accumulated methylmalonic acid serum levels at breast cancer diagnosis are not associated with distant metastases.

Recent evidence suggests that age-accumulated methylmalonic acid (MMA) promotes breast cancer progression in mice. This study aims to investigate the association between baseline serum MMA concentrations in patients with breast cancer and the development of subsequent distant metastases. We included 32 patients with early Luminal B-like breast cancer (LumB, median age 62.4y) and 52 patients with early triple-negative breast cancer (TNBC, median age 50.5y) who developed distant metastases within 5years. They were matched to an equal number of early breast cancer patients (median age 62.2y for LumB and 50.5y for TNBC) who did not develop distant metastases with at least 5years of follow-up. Baseline serum MMA levels at breast cancer diagnosis showed a positive correlation with age (P < 0.001) and a negative correlation with renal function and vitamin B12 (all P < 0.02), but no statistical association was found with BMI or tumor stage (P > 0.6). Between matched pairs, no significant difference was observed in MMA levels, after adjusting for kidney function and age (P = 0.19). Additionally, in a mouse model, a significant decline in MMA levels was observed in the tumor-bearing group compared to the group without tumors before and after tumor establishment or at identical times for the control group (P = 0.03). Baseline serum MMA levels in patients with breast cancer are not correlated with secondary distant metastasis. Evidence in the mouse model suggests that the presence of a tumor perturbates MMA levels.

Association between dietary macronutrient composition and plasma one-carbon metabolites and B-vitamin cofactors in patients with stable angina pectoris.

Elevated plasma concentrations of several one-carbon metabolites are associated with increased CVD risk. Both diet-induced regulation and dietary content of one-carbon metabolites can influence circulating concentrations of these markers. We cross-sectionally analysed 1928 patients with suspected stable angina pectoris (geometric mean age 61), representing elevated CVD risk, to assess associations between dietary macronutrient composition (FFQ) and plasma one-carbon metabolites and related B-vitamin status markers (GC-MS/MS, LC-MS/MS or microbiological assay). Diet-metabolite associations were modelled on the continuous scale, adjusted for age, sex, BMI, smoking, alcohol and total energy intake. Average (geometric mean (95 % prediction interval)) intake was forty-nine (38, 63) energy percent (E%) from carbohydrate, thirty-one (22, 45) E% from fat and seventeen (12, 22) E% from protein. The strongest associations were seen for higher protein intake, i.e. with higher plasma pyridoxal 5'-phosphate (PLP) (% change (95 % CI) 3·1 (2·1, 4·1)), cobalamin (2·9 (2·1, 3·7)), riboflavin (2·4 (1·1, 3·7)) and folate (2·1 (1·2, 3·1)) and lower total homocysteine (tHcy) (-1·4 (-1·9, -0·9)) and methylmalonic acid (MMA) (-1·4 (-2·0, -0·8)). Substitution analyses replacing MUFA or PUFA with SFA demonstrated higher plasma concentrations of riboflavin (5·0 (0·9, 9·3) and 3·3 (1·1, 5·6)), tHcy (2·3 (0·7, 3·8) and 1·3 (0·5, 2·2)) and MMA (2·0 (0·2, 3·9) and 1·7 (0·7, 2·7)) and lower PLP (-2·5 (-5·3, 0·3) and -2·7 (-4·2, -1·2)). In conclusion, a higher protein intake and replacing saturated with MUFA and PUFA were associated with a more favourable metabolic phenotype regarding metabolites associated with CVD risk.

Efficacy and tolerance of oral versus parenteral cyanocobalamin supplement in hypocobalaminaemic dogs with chronic enteropathy: a controlled randomised open-label trial.

Determine comparative tolerance of daily oral and weekly parenteral cobalamin supplementation, in hypocobalaminaemic dogs with chronic enteropathy. Determine whether oral is as effective as parenteral supplementation at achieving eucobalaminaemia, in hypocobalaminaemic dogs with protein-losing enteropathy, severe hypocobalaminaemia or high canine inflammatory bowel disease activity index at inclusion. Thirty-seven client-owned dogs with hypocobalaminaemia and clinical signs of chronic enteropathy were prospectively enrolled in three UK referral centres. Dogs were randomly allocated to daily oral for 12 weeks or weekly parenteral cobalamin supplementation for 6 weeks and one additional dose 4 weeks later. Serum cobalamin, body condition score, canine inflammatory bowel disease activity index and bodyweight were assessed at inclusion, weeks 7 and 13. Serum methylmalonic acid concentration was evaluated at inclusion and at week 13. Owners completed treatment adherence, palatability, tolerance and satisfaction questionnaires at week 13. Nineteen dogs completed the study. All dogs orally supplemented achieved normal or increased cobalaminaemia at weeks 7 and 13. There was no statistical difference in cobalamin concentration at week 13 in dogs treated with oral or parenteral supplementation, regardless of presence of protein-losing enteropathy, severity of hypocobalaminaemia or canine inflammatory bowel disease activity index at inclusion. Serum methylmalonic acid concentration was not significantly different between oral and parenteral groups, neither were treatment adherence, satisfaction, and tolerance scores at week 13. Oral is as effective and as well-tolerated as parenteral cobalamin supplementation in hypocobalaminaemic dogs with chronic enteropathy and severe clinical or biochemical phenotypes, and should be considered as a suitable treatment option regardless of disease severity.

Variable phenotypes and outcomes associated with the MMACHC c.482G &gt; A mutation: follow-up in a large CblC disease cohort

Abstract Background The aim of this study was to characterize the variable phenotypes and outcomes associated with the methylmalonic aciduria and homocystinuria type C protein gene (MMACHC) c.482G &gt; A mutation in 195 Chinese cases with CblC disease. Methods We carried out a national, retrospective multicenter study of 195 Chinese patients with CblC disease attributable to the MMACHC c.482G &gt; A variant either in a homozygous or compound heterozygous state. The control group consisted of 200 patients diagnosed with CblC disease who did not possess the c.482G &gt; A mutation. Clinical features, including disease onset, symptoms, biochemical metabolites, gene mutation, and follow-up outcomes were reviewed and analyzed in detail. The median follow-up period spanned 3 years and 8 months, with a range of 1 year and 2 months to 12 years and 10 months. Results Among 195 patients carrying the c.482G &gt; A variant, 125 (64.1%) cases were diagnosed by newborn screening (NBS), 60 (30.8%) cases were detected due to disease onset, and 10 (5.1%) cases were identified from sibling diagnoses. One hundred and seventeen (93.6%) individuals who were diagnosed by NBS, and nine patients who came from sibling diagnoses remained asymptomatic in this study. From 69 symptomatic patients of the c.482G &gt; A group, more patients presented with later onset, and the top six common clinical symptoms at disease onset were developmental delay (59.4%), lower limb weakness and poor exercise tolerance (50.7%), cognitive decline (37.7%), gait instability and abnormal posture (36.2%), seizures (26.1%), and psychiatric and behavioral disturbances (24.6%). In the 159 symptomatic patients lacking c.482G &gt; A variants, the most frequently observed clinical manifestations at disease onset included developmental delay (81.8%), lethargy and feeding difficulty (62.9%), lower limb weakness and poor exercise tolerance (54.7%), prolonged neonatal jaundice (51.6%), vomiting (47.2%), and seizures (32.7%). Before treatment, the levels of blood propionylcarnitine, propionylcarnitine/acetylcarnitine ratio, and homocysteine in the c.482G &gt; A group were significantly lower (P &lt; 0.05) than those in the non-c.482G &gt; A group, while the concentration of urinary methylmalonic acid was slightly lower (P &gt; 0.05). The degree of decline in the above metabolites after treatment in different groups significantly differed in both plasma total homocysteine values and urinary methylmalonic acid levels (P &lt; 0.05). In patients carrying the c.482G &gt; A variant compared with the non-c.428G &gt; A group, there were markedly lower rates of mortality (0.5% vs. 2.0%) and developmental delay (20.5% vs. 65.5%). When compared with individuals diagnosed due to disease onset, those identified through NBS in either group exhibited a reduced proportion of disease onset (6.7% vs. 100% in the c.482G &gt; A group, 54.4% vs. 100% in the non-c.482G &gt; A group), lower mortality (0.0% vs. 1.7% in the c.482G &gt; A group, 0.0% vs. 3.6% in the non-c.482G &gt; A group), and had a higher percentage of patients exhibiting normal psychomotor and language development (99.3% vs. 33.3% in the c.482G &gt; A group, 58.9% vs. 10.9% in the non-c.482G &gt; A group). Conclusions The c.482G &gt; A variant in MMACHC is associated with late-onset and milder phenotypes of CblC disease. Patients with this mutation tend to have a relatively better response to hydroxocobalamin, better metabolic control, and more favorable neurological outcomes. NBS and other appropriate pre-symptomatic treatments seem to be helpful in early diagnosis, resulting in favorable clinical outcomes.

Ferritin Reference Ranges in an Adult Population of Working-Age Adults without Anemia

Introduction Considerable controversy has surrounded the creation of reference intervals for ferritin within tested populations. This is particularly true for women and has been attributed to a high prevalence of nonanemic iron deficiency due to physiologic blood loss during menses and physiologic iron transfer during pregnancy. The Quest Blueprint for Wellness (BFW) program is an annual health screening that provides a range of testing to Quest employees and families. Using deidentified data on 24,812 individuals (55% female; age range 18-80 years old) collected as part of this program, we studied the relationship between serum ferritin and characteristics of the study population, red blood cell parameters, and iron saturation in order to better define normal reference ranges for serum ferritin. Methods Test results of participants in the annual BFW screening program conducted between January 2022 and May 2023 were identified (26,535 [53% female]); tests included hematocrit, hemoglobin, RBC indices (including RDW), total serum iron and total iron binding capacity and CRP. Individuals with abnormalities of hemoglobin, hematocrit or RBC indices (including RDW); serum iron or serum TIBC; or elevated CRP were successively excluded, leaving 24,812 participants (55% female). None of these remaining individuals had a personal history of anemia or an identified ICD-10 code associated with anemia or other RBC disorder. This study population was used in subsequent analyses. Multimodal decomposition (MMD) in R (version 4.2.2) was used to calculate reference intervals based on the distribution of results associated with the healthy study subpopulation that was defined. To address the possibility that the TIBC saturation initially employed (20%) was too low, reference intervals were also determined when varying TIBC saturations from 20%-25%. Results As shown in Table 1, the lower limits of the ranges identified did not vary significantly as the TIBC saturation percent was increased from 20% to 25%. The lower limit for women below 50 years of age ranged from 11-13 ng/mL, which was substantially lower than the lower limits for men of the same age. Over the age of 50, the lower limit of the ferritin reference ranges for women increased, approaching but not equaling or exceeding the values observed for men until ages greater than 70. This may reflect the end of menses and the gradual repletion of iron stores. In contrast, the lower limits of the reference ranges for serum ferritin for men increased at ages 30-40 and then declined and fell below that of women in the eighth decade. Conclusions Comparing the lower range of ferritin values between men and women, these data suggest that iron deficiency may be present in a large proportion of working age women in the absence of anemia or abnormal RBC indices. These data also suggest that normal ferritin values are age dependent for both men and women. These conclusions are tempered by the unavailability of a physiologic reference standard able to demonstrate that iron deficiency is in fact present. The lower limit of the ferritin range for women under the age of 60 and for men over the age of 70 approximates the ferritin values associated with the absence of stainable bone marrow iron. While this test is the traditional “gold standard” it is rarely performed for the evaluation of iron status. The evaluation of iron deficiency at present lacks a physiologic indicator, analogous to the relationship between parathyroid hormone and calcium levels which permitted the definition of blood levels of 25 hydroxyvitamin D that represented sufficiency, or methylmalonic acid concentration in B12 deficiency. The broader availability of measures to assess the functional status of reticuloendothelial iron stores available to support erythropoiesis, such as measurements of hepcidin, would facilitate such an assessment.

Vitamin B12 and Folate Status in Pregnant Females and Their Infants in Norway: Secondary Analysis from the Mommy’s Food Study

BackgroundVitamin B12 and folate are essential micronutrients important for normal infant growth and development. ObjectivesThe aims were to describe vitamin B12 and folate status in pregnant females and their infants according to commonly used status cutoffs and examine the associations between maternal status, maternal supplement use, and breastfeeding and infant status. MethodsPregnant females were recruited at 18 wk gestation in Bergen, Norway. Maternal vitamin B12 and folate status were measured at gestational weeks 18 (n = 136) and 36 (n = 116), and infant status was measured at ages 3 (n = 73) and 6 (n = 74) mo. ResultsAt gestational weeks 18 and 36, respectively, 4.4% and 2.6% of the mothers had plasma cobalamin concentrations <148 pmol/L, 0.7% and 6.9% had methylmalonic acid (MMA) concentrations >0.26 μmol/L, and 3.7% and 30% had folate concentrations <10 nmol/L. None of the females had total homocysteine (t-Hcy) concentrations >13 μmol/L or 3 combined indicator of vitamin B12 (cB12) < −0.5. At 3 and 6 mo, respectively, 4.1% and 5.4% of the infants had cobalamin concentrations <148 pmol/L, 63% and 74% had t-Hcy concentrations >6.5 μmol/L, 59% and 66% had MMA concentrations >0.26 μmol/L, and 47% and 60% had cB12 > −0.5. None of the infants had folate concentrations <10 nmol/L. Several of the vitamin B12 biomarkers in infants were associated with maternal vitamin B12 status during pregnancy. Breastfed infants had lower vitamin B12 status (as indicated by plasma cobalamin, t-Hcy, and cB12) than nonbreastfed infants at both 3 and 6 mo. Use of supplements during pregnancy was associated with better vitamin B12 status among infants at 3 and 6 mo, as indicated by infants’ cobalamin and t-Hcy concentrations. ConclusionsSubclinical vitamin B12 deficiency among infants was common and associated with maternal vitamin B12 status during pregnancy and breastfeeding. Among the mothers, an increase in biochemical folate deficiency was discovered toward the end of gestation. Further studies are needed to investigate clinical consequences.This trial was registered at clinicaltrials.gov as NCT02610959.

Functional vitamin B12 deficiency is a consistent feature in hospital admissions for neurological disorders due to the use of nitrous oxide

Introduction: Misuse of inhaled nitrous oxide is a growing concern in France. It is known to alter concentrations of vitamin B12, which is required as a cofactor for methionine synthase and methylmalonyl-CoA mutase activity. Hence, measurement of the concentrations of cobalamin metabolism biomarkers, including vitamin B12, homocysteine, and methylmalonic acid, could assist in the management of patients with a complex clinical presentation or in those who deny the consumption of nitrous oxide. Methods: We retrospectively collected clinical and biological data in patients hospitalized for nitrous oxide use in a university hospital in southern France between January 2020 and October 2022. Results: Thirty-one patients were identified during 34 months; 79% were men with a median age of 23.7 years. Most (97%) presented with peripheral polyneuropathy and/or myelopathy. The median vitamin B12 concentration was 134.6 pmol/L, with 17 of 31 patients having values less than 145 pmol/L (the lower limit of the normal range). The median plasma folate concentration was 20.1 nmol/L, which is within the normal range. The median plasma homocysteine concentration was 87.7 µmol/L (normal range >15 µmol/L), and the median plasma methylmalonic acid concentration was 3.8 µmol/L (normal range >0.5 µmol/L). Conclusion: Nitrous oxide use is an emerging public health problem in France, as shown by the number of patients admitted to our hospital. The presence of a functional vitamin B12 deficiency was a consistent feature that could be helpful in diagnosis in complex cases.

Serum methylmalonic acid concentrations at breast cancer diagnosis significantly correlate with clinical frailty.

Methylmalonic acid (MMA), a by-product of propionate metabolism, is known to increase with age. This study investigates the potential of serum MMA concentrations as a biomarker for age-related clinical frailty in older patients with breast cancer. One hundred nineteen patients ≥ 70years old with early-stage breast cancer were included (median age 76years). G8 screening, full geriatric assessment, clinical parameters (i.e., estimated glomerular filtration rate (eGFR) and body mass index (BMI)), and serum sample collection were collected at breast cancer diagnosis before any therapy was administered. MMA concentrations were measured via liquid chromatography with tandem mass spectrometry. MMA concentrations significantly increased with age and eGFR (all P < 0.001) in this older population. The group with an abnormal G8 (≤ 14, 51% of patients) had significantly higher MMA levels than the group with normal G8 (> 14, 49%): 260nmol/L vs. 188nmol/L, respectively (P = 0.0004), even after correcting for age and eGFR (P = 0.001). Furthermore, in the detailed assessment, MMA concentrations correlated most with mobility (Eastern Cooperative Oncology Group (ECOG) Performance Status and Activities of Daily Living (ADL) tools, all P ≤ 0.02), comorbidity (Charlson Comorbidity Index (CCI) tool, P = 0.005), and polypharmacy (P < 0.001), whereas no significant associations were noted for instrumental ADL (IADL), Mini-Mental State Examination (MMSE), Geriatric Depression Scale-15 (GDS15), Mini Nutritional Assessment-Short Form (MNA-SF), and pain (all P > 0.1). In addition, our results showed that higher MMA levels correlate with poor overall survival in breast cancer patients (P = 0.003). Elevated serum MMA concentrations at initial diagnosis are significantly associated, not only with age but also independently with clinical frailty, suggesting a possible influence of MMA on clinical frailty in older patients with early-stage breast cancer.

Vitamin B12 Status in Recreational Users of Nitrous Oxide: A Systematic Review Focusing on the Prevalence of Laboratory Abnormalities.

The recreational use of nitrous oxide (N2O) as "laughing gas" is a growing problem. The chronic toxicity of N2O is mainly due to its ability to oxidize vitamin B12, making it dysfunctional as a cofactor in metabolic pathways. This mechanism plays a major role in the development of neurological disorders in N2O users. The assessment of vitamin B12 status in N2O users is important but challenging due to the lack of decrease in total vitamin B12 in most cases despite genuine vitamin B12 functional deficiency. Other biomarkers, such as holotranscobalamin (holoTC), homocysteine (tHcy) and methylmalonic acid (MMA), are interesting candidates to properly assess vitamin B12 status. Here, we conducted a systematic review of case series in order to assess the prevalence of abnormal values of total vitamin B12, holoTC, tHcy and MMA in recreational N2O users, which is an important prerequisite for determining the best screening strategy in future guidelines. We included 23 case series (574 N2O users) from the PubMed database. Total circulating vitamin B12 concentration was low in 42.2% (95% confidence interval 37.8-46.6%, n = 486) of N2O users, while 28.6% (7.5-49.6%, n = 21) of N2O users had low circulating concentrations of holoTC. tHcy levels were elevated in 79.7% (75.9-83.5%, n = 429) of N2O users, while 79.6% (71.5-87.7%, n = 98) of N2O users had increased concentrations of MMA. In summary, the increases in tHcy and MMA were the most prevalent abnormalities, and should be measured alone or in combination in symptomatic N2O users rather than total vitamin B12 or holoTC.

Serum cobalamin and methylmalonic acid concentrations in juvenile dogs with parvoviral enteritis or other acute enteropathies.

Low serum cobalamin concentrations have been associated with ileal malabsorption in dogs with chronic enteropathy. Increased serum methylmalonic acid (MMA) concentrations indicate cobalamin deficiency on a cellular level. Few studies have evaluated serum cobalamin concentrations or methylmalonic acid concentrations in juvenile dogs with parvoviral enteritis or nonparvoviral acute enteropathies. Evaluate serum cobalamin and methylmalonic acid concentrations in juvenile dogs (6 weeks to 10 months old) with parvoviral enteritis or nonparvoviral acute enteropathy. Thirty-one juvenile dogs with parvoviral enteritis, 29 dogs with nonparvoviral acute diarrhea (NPVAD), and 40 healthy juvenile control dogs. Single-center, prospective, observational, cross-sectional study. Serum cobalamin and, when sufficient serum was available, MMA concentrations were measured. Most serum cobalamin concentrations were within the adult reference interval. Serum cobalamin concentrations in healthy dogs (median, 848 ng/L; range, 293-1912 ng/L) were significantly higher than in dogs with parvoviral enteritis (P = .0002; median, 463 ng/L; range, <150-10 000 ng/L) or dogs with NPVAD (P = .02; median, 528 ng/L; range, 160-8998 ng/L). Serum MMA concentrations were not significantly different between groups (healthy dogs: median, 796 nmol/L; range, 427-1933 nmol/L; parvoviral enteritis: median, 858 nmol/L; range, 554-3424 nmol/L; NPVAD: median, 764 nmol/L; range, 392-1222 nmol/L; P = .1). Juvenile dogs with parvoviral enteritis or NPVAD had lower serum cobalamin concentrations than healthy juvenile dogs. However, based on serum MMA concentrations cellular cobalamin deficiency was not apparent.

Magnetic MXene-based molecularly imprinted electrochemical sensor for methylmalonic acid.

Anovel magnetic Ti3C2Tx-MXene/Fe3O4 composite was prepared from Ti3C2Tx and magnetic Fe3O4. The characterizations by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) exhibited that the Ti3C2Tx/Fe3O4 nanomaterial presented an outstanding conductivity and a large specific area, which could improve the electron transfer rate, leading to the amplification of thesensor's signal. Furthermore, an ultrasensitive molecularly imprinted electrochemical sensor based on MXene/Fe3O4 composites was fabricated for detecting methylmalonic acid (MMA) with high selectivity. The current intensity of differential pulse voltammetry of the sensor presented a good linear relationship with the logarithm of MMA concentration ranging from 9 × 10-15 mol L-1 to 9 × 10-13 mol L-1. The detection limit of the sensor was 2.33 × 10-16 mol L-1. Thefabricated sensor was utilized for detecting MMA in human serum samples with excellent recoveries. Therefore, this method significantly improved the sensitivity of detection, and constitutes an affordablesensing platform for trace detection of organic carboxylic acid.

Vitamin B12 in Cats: Nutrition, Metabolism, and Disease.

Cobalamin is a water-soluble molecule that has an important role in cellular metabolism, especially in DNA synthesis, methylation, and mitochondrial metabolism. Cobalamin is bound by intrinsic factor (IF) and absorbed in the ileal tract. The IF in cats is synthesized exclusively by pancreatic tissue. About 75% of the total plasma cobalamin in cats is associated with transcobalamin II, while in this species, transcobalamin I is not present. In cats, the half-life of cobalamin is 11-14 days. Diagnostic biomarkers for B12 status in cats include decreased levels of circulating total cobalamin and increased levels of methylmalonic acid. The reference interval for serum cobalamin concentrations in cats is 290-1500 ng/L, and for the serum methylmalonic acid concentration, it is 139-897 nmol/L. Therapy for hypocobalaminemia mainly depends on the underlying disease. In some cases, subcutaneous or intramuscular injection of 250 μg/cat is empirically administered. In recent years, it has been demonstrated that oral cobalamin supplementation can also be used successfully in dogs and cats as a less invasive alternative to parental administration. This review describes the current knowledge regarding B12 requirements and highlights improvements in diagnostic methods as well as the role of hypocobalaminemia in its associated diseases.

Functional vitamin B12 deficiency: Improving methylmalonic acid reference intervals in urine

Background-AimMost laboratory requests focus on the detection of possible vitamin B12 deficiency. In this context, methylmalonic acid (MMA) is reported as the best biomarker.The aim of our study was to establish the biological reference interval for MMA in urine, and assess the influence of age, sex, and vitamin B12 status on MMA concentrations. MethodsThis is a prospective observational study considering individuals with normal results for blood count and liver and kidney function. Individuals who presented supplementation, any pathology or treatment that could cause cobalamin metabolism disorders, and pregnant women were excluded. Likewise, individuals whose vitamin B12 result presented antibody-mediated interference were excluded.Individuals were grouped by age-group and sex. Reference intervals were determined by non-parametric calculation (percentiles 1–99). ResultsIt was established a single reference interval [0.52 (CI90%: 0.50–0.54) – 5.75 (CI90%: 5.57–6.17) mmolMMA/mol creatinine], with 100 % of individuals with MMA above the upper limit of reference presenting a total vitamin B12 concentration ≤ 238 pmol/L. ConclusionThe establishment of optimal reference intervals for methylmalonic acid excretion in urine is crucial in individuals with a suspicion of functional vitamin B12 deficiency. However, the possibility of establishing a cut-off value for total vitamin B12 suggesting subclinical deficiency remains a challenge for this magnitude.

Abstract PD6-03: PD6-03 Serum methylmalonic acid concentrations at breast cancer diagnosis strongly correlate with frailty: a retrospective cross-sectional study

Abstract Introduction: Frailty commonly occurs in older persons, including those with breast cancer diagnoses. Methylmalonic acid (MMA), a metabolite and by-product of propionate metabolism, is known to increase significantly with aging. The relation between MMA concentrations and frailty is currently unknown. Objectives: A cross-sectional study was performed to study the association between baseline serum MMA concentrations and clinical frailty (estimated by G8 screening) in older patients with newly diagnosed breast cancer. Methods: 163 patients ≥70 years old with early-stage breast cancer were included (median age 76y). G8 screening and serum sample collection were performed at breast cancer diagnosis before any therapy was administered. MMA concentrations were measured via liquid chromatography with tandem mass spectrometry (LC-MS-MS). Results: MMA concentrations significantly increased with age (rs=0.3, p&amp;lt;.0001) and serum creatinine levels (rs=0.5, p&amp;lt;.0001) in this older population. The group with an abnormal G8 (≤14/17 = ‘frail’, 48% of patients) had significantly higher MMA levels than the group with normal G8 (&amp;gt;14/17 = ‘fit’, 52%): 250nM vs. 189 nM, respectively (p=.0002). Higher MMA concentrations were independently associated with abnormal G8 (Odds ratio, 1.003, 95%CI 1.0 to 1.006, p=.04) after adjusting for age and serum creatinine levels. Among the different components of G8, MMA concentrations correlated most with weight loss (rs= -0.18, p=.02), mobility (rs= -0.23, p=.002), and polypharmacy (rs= -0.22, p=.005). Conclusion: Elevated serum MMA concentrations at breast cancer diagnosis are significantly associated, not only with age but also independently with clinical frailty in older patients with early-stage breast cancer. MMA may be further evaluated as a biomarker of frailty in older persons with breast cancer. Citation Format: Qi Wu, Sigrid Hatse, Cindy Kenis, Yentl Lambrechts, Kevin Punie, Patrick Neven, Ann Smeets, Annouschka Laenen, Ana Gomes, Sarah-Maria Fendt, Hans Wildiers. PD6-03 Serum methylmalonic acid concentrations at breast cancer diagnosis strongly correlate with frailty: a retrospective cross-sectional study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD6-03.

Abstract P2-11-18: Serum methylmalonic acid concentrations at breast cancer diagnosis are not associated with distant metastases

Abstract Introduction: Methylmalonic acid (MMA), a metabolite and by-product of propionate metabolism, promotes breast cancer (BC) progression in mice via the transforming growth factor-beta (TGFβ) signaling pathway (Gomes et al, Nature 2020). It is currently unknown if this effect also exists in patients with BC. Objectives: To investigate the association between baseline serum MMA concentrations in patients at BC diagnosis and development of distant metastases via a matched case-control study. Methods: We included 32 patients with early Luminal B-like BC (Lumb, median age 62.4y) and 52 patients with early triple-negative BC (TNBC, median age 50.5y) who developed distant metastases within 5 years. They were matched to an equal number of early BC patients with at least 5 years of follow-up (median age 62.2y for Lumb and 50.5y for TNBC) who did not develop distant metastases with at least 5 years of follow-up. Matching was performed based on age at diagnosis date (± 5y), tumor stage, and treatment received ((neo)adjuvant chemotherapy and radiotherapy, yes/no). Serum MMA concentrations were determined by liquid chromatography with tandem mass spectrometry (LC-MS-MS). Summary statistics, paired analyses, and multiple conditional logistic regression analyses were performed with and without adjusting for potential covariates (age, kidney function, and tumor stage). Results: Baseline serum MMA at BC diagnosis significantly correlated with age (rs=0.35, p=.005 in Lumb; rs=0.35, p=.0003 in TNBC), and negatively correlated with kidney function assessed by estimated glomerular filtration rate (eGFR, rs= -0.42, p=.0005 in Lumb; rs= -0.32, p=.0009 in TNBC). MMA concentrations at diagnosis were not associated with distant metastases in either subtype, after adjusting for kidney function, age, and tumor stage (all p&amp;gt;.05). Next, we categorized BC cases in the public TCGA (n=174 for Lumb; n=140 for TNBC), METABRIC (n=461 for Lumb; n=199 for TNBC), and GSE25066 (n=78 for Lumb; n=182 for TNBC) database according to their 5-year metastatic status, and analyzed the TGFβ signaling pathway activity of primary BC. Like MMA concentrations, a gene expression signature of TGFβ signaling was not associated with distant metastases in patients with BC. Conclusion: Baseline serum MMA concentrations and a gene signature for TGFβ signaling at BC diagnosis are not associated with distant metastases among patients with Lumb and TNBC subtypes. Citation Format: Qi Wu, Sigrid Hatse, Juan F. García, Patricia Altea-Manzano, Jaak Billen, Mélanie Planque, Anke Vandekeere, Yentl Lambrechts, François Richard, Annouschka Laenen, Kevin Punie, Patrick Neven, Ines Nevelsteen, Giuseppe Floris, Christine Desmedt, Ana Gomes, Sarah-Maria Fendt, Hans Wildiers. Serum methylmalonic acid concentrations at breast cancer diagnosis are not associated with distant metastases [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-11-18.

Correlations between circulating methylmalonic acid levels and all-cause and cause-specific mortality among patients with diabetes.

Evidence regarding serum methylmalonic acid (MMA) levels and mortality in individuals with diabetes is limited. This study aimed to evaluate the correlation between MMA and all-cause and cause-specific deaths in patients with diabetes. This is a population-based cohort study based on data from both the National Health and Nutrition Examination Survey (NHANES) and National Death Index from 1999 to 2014. We assessed the association of serum MMA concentrations with mortality using Cox proportional hazard models after adjusting for lifestyle, demographic factors, and comorbidities. Among the 3,097 participants, 843 mortalities occurred during a median follow-up of 4.42 years. There were 242 deaths due to cardiovascular disease (CVD) and 131 cancer-associated deaths. After multivariate adjustment, elevated serum MMA levels were markedly correlated with a high risk of all-cause, CVD-, and cancer-related deaths. Each one-unit increase in the natural log-transformed MMA level correlated with increased risk of all-cause mortality (2.652 times), CVD mortality risk (3.153 times), and cancer-related mortality risk (4.514). Hazard ratios (95% confidence intervals [CIs]) after comparing participants with MMA < 120 and ≥250 nmol/L were 2.177 (1.421-3.336) for all-cause mortality, 3.560 (1.809-7.004) for CVD mortality, and 4.244 (1.537-11.721) for cancer mortality. Higher serum MMA levels were significantly associated with higher all-cause, CVD, and cancer mortality. These findings suggest that maintaining lower MMA status may lower mortality risk in individuals with diabetes.

The Effects of Proton Pump Inhibitors in Acid Hypersecretion-Induced Vitamin B12 Deficiency: A Systematic Review (2022).

Gastroesophageal reflux disease (GERD) is the most common disease, for which proton pump inhibitors (PPIs) are a widely used class of drugs. Due to their efficacy and relative safety profile, PPIs are used chronically by GERD patients. Although it is a safe drug, particular attention focuses on the long-term adverse effects of PPI. The association with vitamin deficiencies has received additional focus since chronic PPI treatment increases the incidence of vitamin B12 deficiency, especially in the elderly. However, numerous studies regarding the establishment of an association between PPI and vitamin B12 status revealed conflicting results. In this systematic review, we systematically examined observational studies that focused on the impact of chronic PPI effects on vitamin B12 absorption and diagnostic biomarkers of vitamin B12 deficiency. Our review showed significant changes in diagnostic biomarkers of vitamin B12 status in long-term PPI users, including elevated homocysteine and methylmalonic acid (MMA) concentration levels defining cellular vitamin B12 deficiency. Although there is uncertainty regarding the exact mechanism, it supports the concept that long-term intake of PPI can have clinical implications for vitamins.

233 (PB-057) Poster - Serum methylmalonic acid concentrations at breast cancer diagnosis are not associated with distant metastases

Background: Methylmalonic acid (MMA), a metabolite and by-product of propionate metabolism, promotes breast cancer (BC) progression in mice via the transforming growth factor beta (TGFβ) signaling pathway (Gomes et al, Nature 2020). It is currently unknown if this effect also exists in patients with BC. This study is to investigate the association between baseline serum MMA concentrations in patients at BC diagnosis and the development of distant metastases via a matched case-control study.