Methylmalonic Acid Concentrations Research Articles

Bone Health Assessment in Patients with Methylmalonic Acidemia

Abstract Background Methylmalonic acidemia (MMA) is a genetically heterogeneous disorder of methylmalonate and cobalamin metabolism. Isolated MMA is a rare inherited disorder of organic acid metabolism associated with elevated methylmalonic acid concentration in the blood and urine without elevation of homocysteine level or malonic acid. Nutritional intervention for MMA patients includes dietary restriction of proteins along with medical food and dietary supplements. Decreased bone mineral density (BMD) is a widely accepted complication of the life-long protein restricted diet in addition to accumulation of acids and toxic metabolites in those patients. Aim of the Study To investigate the effect of restricted and modified diet on bone health in a sample of patients with MMA. Subject and Methods Clinical, nutritional, selected laboratory parameters of bone health and bone mineral density (BMD) assessment by Dual-energy X-ray absorptiometry (DXA) scan of bones were carried out on Egyptian MMA patients from Genetics Clinic, Medical Genetic Department, Ain Shams University. Bone formation was assessed by measurement of serum osteocalcin level while bone resorption was evaluated by serum carboxy terminal telopeptide of collagen type 1 (S-CTX). Results The study included 24 patients from 14 families (13 males and 11 females). Their ages ranged between 5.2 to 26 years with median age of 10 years (IQR: 6.5-14). Consanguineous marriage was present in 91.67 of families. Median age of symptoms was 140 days (IQR: 3.5-332.5) while median age of diagnosis was 12 months (IQR (2.5-40). History of fractures was present in 5 patients (20.83%). Decreased total body BMD was detected in 14 patients (54.5 %) with mean Z score of -1.31 ± 1.38 SD. Decreased spine BMD was present in 21 patients (79.16%) with mean Z score of -1.9 ± 1.1 SD. This decrease was significantly related to non-compliance, chronic acidosis, low serum copper. There was no significant relation between BMD and creatinine, calcium, vitamin D, zinc, selenium, osteocalcin or S-CTX levels. Conclusion MMA patients have decreased BMD related to copper deficiency, poor compliance and chronic acidosis. This resulted in defective bone formation and increased bone resorption.

Effect of oral or subcutaneous administration of cyanocobalamin in hypocobalaminemic cats with chronic gastrointestinal disease or exocrine pancreatic insufficiency.

No prospective study has evaluated the efficacy of oral supplementation with cobalamin in hypocobalaminemic cats. To investigate the efficacy of oral or SC supplementation with cyanocobalamin in normalizing serum cobalamin and methylmalonic acid (MMA) concentrations in hypocobalaminemic cats with chronic gastrointestinal disease (CGID) or exocrine pancreatic insufficiency (EPI). Forty-eight client-owned hypocobalaminemic (<290 ng/L) cats with normal or abnormally high serum MMA concentrations. This study was conducted based on the prospective randomized clinical trial method. Cats with CGID or EPI were randomly assigned to 2 groups that received either oral or SC supplementation with cobalamin (250 μg/cat) for 12 and 10 weeks, respectively, in addition to other medical and dietary interventions. Each cat was evaluated 3 times (baseline, 6-week postsupplementation, and 1-week postcompletion) by measuring serum cobalamin and MMA concentrations. In cats with CGID or EPI, cobalamin concentrations were normalized in all cats that received either oral or SC supplementation (mean 100% [95% CI: 80.6%-100%] in both groups in cats with CGID and 100% [67.6%-100%] in both groups in cats with EPI). Among 37 cats with elevated MMA concentrations at baseline (21 cats with CGID and 16 cats with EPI), MMA concentrations were normalized in most cats with CGID (70% in oral and 82% in SC group) or EPI (88% in both groups). In hypocobalaminemic cats with CGID or EPI, in conjunction with other medical and dietary interventions, both oral and SC supplementation are effective at normalizing serum cobalamin and MMA concentrations.

Implications of hypocobalaminemia as a negative prognostic marker in juvenile dogs with parvovirus enteritis.

Canine Parvovirus 2 (CPV-2) infection poses a significant global health risk to susceptible dogs. Hypocobalaminemia, defined as reduced serum cobalamin (CBL) concentrations, is a recognized complication in chronic enteropathies in adult dogs but remains poorly understood in the context of acute enteropathies, especially in young dogs. The aim of this study was to investigate the frequency and severity of hypocobalaminemia in young dogs with parvovirus enteritis and evaluation of CBL as a predictor of outcome. Thirty client-owned dogs diagnosed with parvovirus infection and thirty healthy controls were enrolled. Clinical, hematological, and biochemical tests, including CBL and serum methylmalonic acid (MMA) concentrations, were assessed. Results indicated a significantly higher prevalence of hypocobalaminemia in dogs with parvovirus enteritis compared to healthy controls, as well as a significant correlation with a disease severity score. Moreover, survivors demonstrated higher CBL concentrations than non-survivors, suggesting an eventual prognostic value of CBL status. However, parenteral CBL supplementation showed no significant effect on serum CBL or MMA concentrations, highlighting potential challenges in CBL uptake at the cellular level. Hypocobalaminemia in this population is caused by multiple factors such as reduced nutritional absorption, gastrointestinal losses, and increased metabolic demands. Further research is needed to develop tailored management strategies, evaluate the effectiveness of CBL supplementation, and understand the mechanisms behind hypocobalaminemia in parvovirus infection.

Excess Folic Acid and Vitamin B12 Deficiency: Clinical Implications?

In the 1940s to 1950s, high-dose folic acid supplements (>5 mg/d) were used clinically to reverse the megaloblastic anemia of vitamin B12 deficiency caused by pernicious anemia. However, this treatment strategy masked the underlying B12 deficiency and possibly exacerbated its neuropathological progression. The issue of masking and exacerbating B12 deficiency has recently been rekindled with the institution of folic acid fortification and the wide-spread use of folic acid supplements. The objectives of this review are to describe clinical and epidemiological evidence that excess folic acid exacerbates B12 deficiency, to summarize a hypothesis to explain this phenomenon, and to provide guidance for clinicians. Cognitive function test scores are lower and blood homocysteine and methylmalonic acid concentrations are higher in people with low B12 and elevated folate than in those with low B12 and nonelevated folate. High-dose folic acid supplementation in patients with pernicious anemia or epilepsy cause significant reductions in serum B12. It is hypothesized that high-dose folic acid supplements cause depletion of serum holotranscobalamin and thus exacerbate B12 deficiency. The evidence for excess folic acid exacerbating B12 deficiency is primarily correlative or from uncontrolled clinical observations, and the hypothesis to explain the phenomenon has not yet been tested. Nonetheless, the evidence is sufficiently compelling to warrant increased vigilance for identifying B12 deficiency in at risk individuals, including older adults and others with low B12 intake or conditions that are associated with B12 malabsorption, who also ingest excessive folic acid or are prescribed folic acid in high doses.

Oral vitamin B12 supplementation in pernicious anemia: a prospective cohort study

BackgroundThe absorption of vitamin B12 is hindered in pernicious anemia (PA) owing to intrinsic factor deficiency. Traditionally, intramuscular vitamin B12 injections were the standard treatment, bypassing the impaired absorption. Although there is potential for oral vitamin B12 supplementation through passive enteral absorption, it is not commonly prescribed in PA owing to limited studies assessing its efficacy. ObjectivesWe aimed to assess the efficacy of oral vitamin B12 supplementation in PA. MethodsWe enrolled participants diagnosed with incident vitamin B12 deficiency related to PA. The diagnosis of PA was based on the presence of classical immune gastritis and of anti-intrinsic factor and/or antiparietal cell antibodies. To evaluate the vitamin B12 status, we measured total plasma vitamin B12, plasma homocysteine, and plasma methylmalonic acid (pMMA) concentration and urinary methylmalonic acid–to–creatinine ratio. Participants were treated with oral cyanocobalamin at a dosage of 1000 μg/d throughout the study duration. Clinical and biological vitamin B12 deficiency related features were prospectively and systematically assessed over the 1-y study duration. ResultsWe included 26 patients with vitamin B12 deficiency revealing PA. Following 1 mo of oral vitamin B12 supplementation, 88.5% of patients were no longer deficient in vitamin B12, with significant improvement of plasma vitamin B12 [407 (297–485) compared with 148 (116–213) pmol/L; P < 0.0001], plasma homocysteine [13.5 (10.9–29.8) compared with 18.6 (13.7–46.8) μmol/L; P < 0.0001], and pMMA [0.24 (0.16–0.38) compared with 0.56 (0.28–1.09) pmol/L; P < 0.0001] concentrations than those at baseline. The enhancement of these biological parameters persisted throughout the 12-month follow-up, with no patients showing vitamin B12 deficiency by the end of the follow-up period. The median time to reverse initial vitamin B12 deficiency abnormalities ranged from 1 mo for hemolysis to 4 mo for mucosal symptoms. ConclusionsOral supplementation with 1000 μg/d of cyanocobalamin has been shown to improve vitamin B12 deficiency in PA.

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.

The utility of methylmalonic acid, methylcitrate acid, and homocysteine in dried blood spots for therapeutic monitoring of three inherited metabolic diseases.

Routine metabolic assessments for methylmalonic acidemia (MMA), propionic acidemia (PA), and homocysteinemia involve detecting metabolites in dried blood spots (DBS) and analyzing specific biomarkers in serum and urine. This study aimed to establish a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous detection of three specific biomarkers (methylmalonic acid, methylcitric acid, and homocysteine) in DBS, as well as to appraise the applicability of these three DBS metabolites in monitoring patients with MMA, PA, and homocysteinemia during follow-up. A total of 140 healthy controls and 228 participants were enrolled, including 205 patients with MMA, 17 patients with PA, and 6 patients with homocysteinemia. Clinical data and DBS samples were collected during follow-up visits. The reference ranges (25th-95th percentile) for DBS methylmalonic acid, methylcitric acid, and homocysteine were estimated as 0.04-1.02 μmol/L, 0.02-0.27 μmol/L and 1.05-8.22 μmol/L, respectively. Following treatment, some patients achieved normal metabolite concentrations, but the majority still exhibited characteristic biochemical patterns. The concentrations of methylmalonic acid, methylcitric acid, and homocysteine in DBS showed positive correlations with urine methylmalonic acid (r = 0.849, p < 0.001), urine methylcitric acid (r = 0.693, p < 0.001), and serum homocysteine (r = 0.721, p < 0.001) concentrations, respectively. Additionally, higher levels of DBS methylmalonic acid and methylcitric acid may be associated with increased cumulative complication scores. The LC-MS/MS method established in this study reliably detects methylmalonic acid, methylcitric acid, and homocysteine in DBS. These three DBS metabolites can be valuable for monitoring patients with MMA, PA, and homocysteinemia during follow-up. Further investigation is required to determine the significance of these DBS biomarkers in assessing disease burden over time.

Breastfeeding and biomarkers of folate and cobalamin status in Norwegian infants: a cross-sectional study

Abstract Folate and vitamin B12 (cobalamin) are essential for growth and development. This cross-sectional study aims to describe folate and vitamin B12 status according to infant age and breastfeeding practices in Norwegian infants. Infants aged 0–12 months (n = 125) were recruited through public health clinics. We registered breastfeeding status and measured serum concentrations of folate, cobalamin, total homocysteine (tHcy), and methylmalonic acid (MMA). The associations between infant age, breastfeeding, and biomarker concentrations were estimated in regression models. The mean (SD) age was 24 (16) weeks, and 42% were exclusively breastfed, 38% were partially breastfed, and 21% were weaned. Overall, median (IQR) folate, cobalamin, tHcy, and MMA concentrations were 47 (35–66) nmol/L, 250 (178–368) pmol/L, 6.99 (5.69–9.27) µmol/L, and 0.35 (0.24–0.83) µmol/L, respectively. None of the infants were folate deficient, 15% were vitamin B12 deficient (&lt; 148 pmol/L), and 23% had low vitamin B12 status (148–221 pmol/L). Elevated tHcy (&gt; 6.5 μmol/L) and MMA (&gt; 0.26 μmol/L) were found in 62% and 69% of the infants, respectively. Compared to weaned, exclusively or partially breastfed infants were younger and had 46% higher tHcy concentrations (P &lt; 0.001), in addition to 47% and 39% lower cobalamin concentrations (P &lt; 0.001), respectively. However, the observed biomarker concentrations appeared to be independent of infant age. In conclusion, low vitamin B12 status was prevalent and appeared to be more common in the younger exclusively breastfed compared to older weaned infants. The implications of low vitamin B12 status in infancy are unknown and require further investigation.

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

BackgroundThe 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 > A mutation in 195 Chinese cases with CblC disease.MethodsWe carried out a national, retrospective multicenter study of 195 Chinese patients with CblC disease attributable to the MMACHC c.482G > 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 > 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.ResultsAmong 195 patients carrying the c.482G > 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 > 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 > 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 > A group were significantly lower (P < 0.05) than those in the non-c.482G > A group, while the concentration of urinary methylmalonic acid was slightly lower (P > 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 < 0.05). In patients carrying the c.482G > A variant compared with the non-c.428G > 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 > A group, 54.4% vs. 100% in the non-c.482G > A group), lower mortality (0.0% vs. 1.7% in the c.482G > A group, 0.0% vs. 3.6% in the non-c.482G > A group), and had a higher percentage of patients exhibiting normal psychomotor and language development (99.3% vs. 33.3% in the c.482G > A group, 58.9% vs. 10.9% in the non-c.482G > A group).ConclusionsThe c.482G > 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.CNU96JjhPhuCQHh9ViZTVJVideo (MP4 136794 kb)

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.