Plasma Free Carnitine Research Articles

Secondary carnitine deficiency during refeeding in severely malnourished patients with eating disorders: a retrospective cohort study

BackgroundSecondary carnitine deficiency in patients with anorexia nervosa has been rarely reported. This study aimed to investigate the occurrence of carnitine deficiency in severely malnourished patients with eating disorders during refeeding and assess its potential adverse effects on treatment outcomes.MethodIn a cohort study of 56 female inpatients with eating disorders at a single hospital from March 2010 to December 2020, we measured plasma free carnitine (FC) levels and compared to those of a healthy control group (n = 35). The patients were categorized into three groups based on FC levels: FC deficiency (FC< 20 µmol/L), FC pre-deficiency (20 µmol/L ≤ FC< 36 µmol/L), and FC normal (36 µmol/L ≤ FC).ResultsUpon admission, the patients had a median age of 26 years (interquartile range [IQR]: 21–35) and a median body mass index (BMI) of 13.8 kg/m2 (IQR: 12.8–14.8). Carnitine deficiency or pre-deficiency was identified in 57% of the patients. Hypocarnitinemia was associated with a decline in hemoglobin levels during refeeding (odds ratio [OR]: 0.445; 95% confidence interval [CI]: 0.214–0.926, p = 0.03), BMI at admission (OR: 0.478; 95% CI: 0.217–0.874, p = 0.014), and moderate or greater hepatic impairment at admission (OR: 6.385; 95% CI: 1.170–40.833, p = 0.032).ConclusionsHypocarnitinemia, particularly in cases of severe undernutrition (BMI< 13 kg/m2 at admission) was observed in severely malnourished patients with eating disorders during refeeding, a critical metabolic transition phase. Moderate or severe hepatic impairment at admission was considered a potential indicator of hypocarnitinemia. Although hypocarnitinemia was not associated with any apparent adverse events other than anemia during refeeding, the possibility that carnitine deficiency may be a risk factor for more serious complications during sudden increases in energy requirements associated with changes in physical status cannot be denied. Further research on the clinical significance of hypocarnitinemia in severely malnourished patients with eating disorders is warranted.

Importance of L-carnitine as Biochemical Marker for Semen Quality Preservation after Cryopreservation in Stallions

Background: The aim of this work is to study the significance of carnitine fractions and NO metabolites for the assessment of spermatozoa resistance to cryopreservation, for which purpose these parameters were investigated in seminal plasma of animals divided according to the indices of spermatozoa of stallions subjected to cryopreservation. Methods: There were 18 breeding stallions with an average age of 11.28±5.46 years, all 18 were of Arabian breed. Using cluster analysis of indicators of semen quality, animals were identified into two groups: with high and low sperm resistance to cryopreservation-thawing. We assessed standard quality parameters in fresh and cryopreserved sperm, as well as carnitine and its fractions and NO metabolites in stallions’ seminal plasma, steroid hormones level and carnitine fractions in blood serum. Data were analyzed using JASP. Differences at p less than 0.05 were considered statistically significant. Result: Seminal plasma obtained from animals from the cluster with low motility after cryopreservation-thawing was characterized by a lower concentration of nitric oxide metabolites in 1,79 time (p=0.0415) and free carnitine in 1,64 time (p=0.0349). Positive moderate strength correlation were established between the level of seminal plasma free carnitine and the percentage of live spermatozoa after sperm cryopreservation-thawing.

Plasma Free Amino Acid and Carnitine Levels in Pregnant Women with Hydatidiform Mole: A Case-Controlled Study

Background: To determine plasma free amino acid (FAA) and carnitine levels in pregnant women with hydatidiform mole (HM). Materials and Methods: Twenty-three pregnant women with HM, and 24 healthy pregnant wo-men as controls were enrolled in the study. FAA and carnitine concentrations were measured in plasma using liquid chromatography/tandem mass spectrometry (LC-MS). Results: The levels of alanine, arginine, and valine from the 14 amino acids examined were signif-icantly lower in the HM group than in the healthy group (p = 0.019, p = 0.009, and p = 0.03, respec-tively). In addition, several carnitines, C8DC, C16:1, and C18, of the 27 carnitines examined were significantly higher in the HM group than in the control group (p = 0.021, p = 0.03, and p = 0.021, respectively). Conclusions: This study demonstrated that a decrease in some plasma FAAs and an increase in some plasma carnitine levels might be effective in the pathogenesis of HM.

Association of Acylcarnitines With Maternal Cardiometabolic Risk Factors Is Defined by Chain Length: The S-PRESTO Study

Abstract Context Due to the essential role of carnitine as an intermediary in amino acid, carbohydrate, and lipid metabolism, a detailed characterization of circulating and urinary carnitine concentrations will aid in elucidating the molecular basis of impaired maternal metabolic flexibility and facilitating timely intervention for expectant mothers. Objective To investigate the association of maternal plasma and urinary free carnitine and acylcarnitines with cardiometabolic risk factors. Methods Liquid chromatography tandem mass spectrometry–based quantification of free carnitine and acylcarnitines (C2-C18) was performed on 765 plasma and 702 urine samples collected at preconception, 26 to 28 weeks’ pregnancy, and 3 months postpartum in the Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO) cohort study. Results Plasma concentrations of free carnitine and acylcarnitines decreased coupled with increased renal clearance in pregnancy compared with preconception and postpartum. Renal clearance of carnitine increased with an increase in prepregnancy body mass index (ppBMI) and gestational weight gain. Plasma short-chain acylcarnitines were positively associated with ppBMI, irrespective of the physiological state, while medium- and long-chain acylcarnitines were negatively associated with ppBMI at preconception and postpartum but showed a positive association in pregnancy. Similarly, plasma short-chain acylcarnitines were positively associated with Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) whereas medium- and long-chain acylcarnitines were negatively associated with HOMA-IR at preconception and in pregnancy. Mothers who developed gestational diabetes mellitus during pregnancy had ∼10% higher plasma propionylcarnitine concentration and ∼18% higher urine tiglylcarnitine concentration than mothers with normal glucose metabolism at preconception. Conclusion This study provides the metabolic and physiological basis of maternal carnitine homeostasis, which can be used in assessment of maternal cardiometabolic health at preconception to improve pregnancy outcomes.

Primary Carnitine Deficiency: Rare Cause of Paediatric Dilated Cardiomyopathy, Often Underdiagnosed

Primary carnitine deficiency (PCD) is an autosomal recessive disorder of fatty acid beta-oxidation. Which results from a defect in the transport of carnitine and is one of the rare treatable etiologies of metabolic cardiomyopathies. Affected patients may present with acute metabolic decompensation in infancy or severe cardiomyopathy in childhood. There have also been reports of dramatic sudden infant death syndrome. Early disease detection and treatment with L-carnitine can be lifesaving. We present in this report, a severe case of decompensation of previously undiagnosed dilated cardiomyopathy in a 14-year-old boy, who presented to the pediatric emergency department with acute heart failure, initially suspected to be viral myocarditis. Chest x-ray showed cardiomegaly, echocardiographic findings included hypokinetic dilated cardiomyopathy with reduced ejection fraction at 22%, the respiratory multiplex PCR came back in favor of a SARS-CoV-2 infection, Laboratory test results showed hepatic failure and a low rate of free and total plasma carnitine. His clinical condition deteriorated rapidly, with the onset of cardiogenic shock leading up to his death in the intensive care unit before carnitine therapy was initiated. The aim of this case report is to highlight the importance of searching for a metabolic cause, particularly primary carnitine deficiency, for early treatment and improved prognosis of the disease.

Profile of plasma free amino acids, carnitine and acylcarnitines, and JAK2v617f mutation as potential metabolic markers in children with type 1 diabetic nephropathy.

Fifty diabetic nephropathy (DN) children with type 1 diabetes mellitus (T1DM) and 50 healthy matched controls were included. Chromatographic assays of 14 amino acids, free carnitine and 27 carnitine esters using high-performance liquid chromatography/electrospray ionization-mass spectroscopy, and genetic testing for JAK2v617f mutation using real-time PCR were performed. Patients had significantly lower levels of tyrosine, branched-chain amino acids (BCAAs), and BCAA/AAA (aromatic chain amino acids) ratios, glycine, arginine, ornithine, free carnitine and some carnitine esters (C5, 6, 12 and 16) and higher phenylalanine, phenylalanine/tyrosine ratio and C18 compared with the controls and in the macro-albuminuria vs. the microalbuminuria group (p< 0.05 for all) except for free carnitine. Plasma carnitine was negatively correlated with eGFR (r =-0.488, p= 0.000). There were significant positive correlations between tyrosine with UACR ratio (r =0.296, p= 0.037). The plasma BCAA/AAA ratio showed significant negative correlations with UACR (r =-0.484, p= 0.000). There was a significantly higher frequency of the JAK2V617F gene mutation in diabetic nephropathy patients compared with the control group and in macro-albuminuria than the microalbuminuria group (p= 0.000) for both. When monitoring children with T1DM, plasma free amino acids and acylcarnitine profiles should be considered, especially if they have tested positive for JAK2V617F for the early diagnosis of DN.

Twenty-Four Weeks of L-Carnitine Combined with Leucine Supplementation Does Not Increase the Muscle Carnitine Content in Healthy Active Subjects

Introduction: To increase the total carnitine (TC) content in muscles, L-carnitine (LC) should be co-ingested with carbohydrates to induce an insulin response. Leucine has an insulin secretagogue effect. Therefore, the primary aim of this study was to examine the effects of 24 weeks of LC and leucine supplementation on the skeletal muscle TC content, muscle mass, and strength in active college-aged subjects. The secondary aim was to determine the activation of the Akt/mTOR signaling pathway in skeletal muscles after supplementation. Methods: Over the 24 weeks, the participants were supplemented with either 1 g of LC-L-tartrate and 3 g of leucine per day (LC + L group; n = 7) or 4 g of leucine per day (L group; n = 7) as a placebo. Before and 24 weeks after the initiation of the study protocol, the free carnitine (FC) and TC content in plasma and muscle samples, as well as body composition and muscle strength, were measured. In addition, the phosphorylation of the Akt/mTOR pathway proteins in muscles was evaluated. Results: Plasma FC and TC content increased in LC + L group after 24 weeks of supplementation (p = 0.003 and 0.010, respectively). However, the skeletal muscle FC and TC contents were not affected by the supplementation protocol. No changes were noted in the body mass and composition; serum insulin-like growth factor-1 concentration; and phosphorylation of the signaling pathway proteins Akt, mTOR, and p70S6K. Conclusion: LC supplementation may have the potential to exert beneficial effects in muscle atrophy. Therefore, additional research is necessary to investigate the effect of various LC supplementation protocols.

PS-B08-7: L-CARNITINE AMELIORATES DIABETIC KIDNEY DISEASE BY ALLEVIATING MITOCHONDRIAL ABNORMALITY IN SDT-FATTY RATS

Background and Aims: Abnormal fatty acid metabolism is associated with the progression of diabetic kidney disease (DKD). Carnitine plays a central role in β;-oxidation and energy production by transporting long-chain fatty acids from the cytoplasm to the mitochondria. Recently, we found that significant ectopic fat was accumulated in the kidney tissue in DKD patients compared with those in minimal change kidney disease patients. Juvenile visceral steatosis (jvs) mice, described as an animal model for systemic carnitine deficiency, introduce a marked ectopic fat accumulation in the kidney. These findings suggest that abnormal carnitine dynamics in DKD cause ectopic fat accumulation due to abnormality of the fatty acid metabolism. However, the association between abnormalities of carnitine metabolism and the progression of DKD is unknown. Method: Spontaneously Diabetic Torii (SDT) fatty rat, an obese type 2 diabetic model was used. Unilateral nephrectomy was performed and 0.3% salt water was administered at 6 weeks of age, and created a renal dysfunction model in SDT fatty rat (DKD model). Age-matched male Sprague-Dawley (SD) rat was used as a control. Experiment 1: We compared 3 groups; SD rats (n = 8), SDT fatty rats (n = 8), DKD rats (n = 8). Experiment 2: We compared 3 groups; SD rats with sham operation (n = 8), DKD rats (n = 7), DKD rats treated with L-carnitine administration (0.75% L-carnitine diet) for 10 weeks (n = 6). All rats were sacrificed at 17 weeks old. Carnitine was measured by the enzyme cycling method. Acylcarnitine was analyzed by the tandem-mass spectrometry. Results: Plasma and renal free carnitine levels and short/middle-long chain acylcarnitine ratio were significantly decreased in DKD rats compared with those in SD and SDT fatty rats. The renal expression levels of organic cation / carnitine transporter 2 (OCTN2), carnitine palmitoyl transferase 1a (CPT1a), CPT2 and carnitine acetyltransferase (CrAT) were significantly decreased in DKD rats compared with those in SD and SDT fatty rats. Similarly, peroxisome proliferator-activated receptor γ co-activator 1α (PGC1α) activity was decreased in DKD rats. L-carnitine administration significantly improved renal function, urinary albumin excretion, interstitial fibrosis and renal ectopic fat accumulation in DKD model rats. L-carnitine administration ameliorated the decrease of renal OCTN2, CPT1a, CPT2 and CrAT protein expression, and significantly improved PGC1α activity in DKD model rats. Furthermore, L-carnitine administration mitigated lipid peroxidation and mitochondrial dysfunction in DKD rats. Conclusion: L-carnitine administration might be a promising therapeutic strategy for improving renal function by alleviating mitochondrial dysfunction in DKD rat model.

Carnitine Administration and 123I-BMIPP Washout Rate in Hemodialysis Patients with Triglyceride Deposit Cardiomyovasculopathy.

Triglyceride deposit cardiomyovasculopathy (TGCV) is an emerging rare heart disease with high mortality, characterized by defective intracellular lipolysis of triglycerides (TG). We developed diagnostic criteria for TGCV, in which low washout rate of BMIPP (BMIPP-WR) is a key factor. The working group of the Japan Society of Nuclear Cardiology recently published practice recommendations for measuring BMIPP-WR. We reported that hemodialysis (HD) patients with TGCV exhibited a markedly higher cardiovascular risk than those without TGCV. Secondary carnitine deficiency is common in patients undergoing HD, as carnitine is removed from the circulation. However, clinical evidence linking carnitine levels to BMIPP-WR is limited. Here we report the effect of L-carnitine administration on the BMIPP-WR in 9 chronic HD patients with TGCV in a retrospective cohort. The mean age at TGCV diagnosis was 59 years. Following standard doses of oral L-carnitine administration, plasma free carnitine levels significantly increased. However, BMIPP-WR was not changed. In normal condition, most BMIPP taken up were esterified/incorporated into TG pool, hydrolyzed by intracellular lipases, and then transported by carnitine shuttle to mitochondria. In TGCV, intracellular TG lipolysis is defective. During the intracellular metabolism of BMIPP, carnitine shuttling occurs downstream of TG lipolysis. Therefore, even when carnitine levels were increased, BMIPP-WR did not change in patients with TGCV who underwent chronic HD. A phase IIb/III clinical trial for TGCV, is underway (jRCT2051210177). Increased awareness of the disease concept of TGCV, along with its diagnostic principles and procedures using BMIPP scintigraphy, is warranted.

The association between plasma carnitines and duration of diabetic ketoacidosis treatment in children with type 1 diabetes.

The aim of this study is to determine the plasma free carnitine and acyl-carnitine levels at the timeof diabetic ketoacidosis (DKA) diagnosis, and attheend of DKA treatment and to investigate their association with the duration of DKA treatment in children with DKA. A total of 40 children with DKA who were treated consecutively in a tertiary health center for DKA were included in the study. The median age of the children was 11.3years (1.1-17.5) and 25 of them (62.5%) were girls.In addition to routine blood tests, plasma free carnitine and acyl-carnitine levels were measured just before the start of intravenous insulin therapy and at the time of discontinuation of intravenous insulin therapy when DKAtherapy was completed. There was no difference in plasma free carnitine and acyl-carnitine levels before and after DKA treatment (p=0.776 and p=0.743 respectively). However, while the frequency of low plasma free carnitine was 30% at the beginning of the treatment, it was observed that this frequency was 20% at the end of the DKA treatment. There was no correlation between duration of DKA treatment and plasma free carnitine or acyl-carnitine levels at admission (p=0.497, r=-0.111 and p=0.474, r=0.116 respectively). There is no a relationship between duration of DKA treatment and plasma free carnitine or acyl-carnitine level at admission in children with DKA.

Assessment of carnitine excretion and its ratio to plasma free carnitine as a biomarker for primary carnitine deficiency in newborns.

In the Netherlands, newborns are referred by the newborn screening (NBS) Program when a low free carnitine (C0) concentration (<5 μmol/l) is detected in their NBS dried blood spot. This leads to ~85% false positive referrals who all need an invasive, expensive and lengthy evaluation. We investigated whether a ratio of urine C0 / plasma C0 (RatioU:P) can improve the follow-up protocol for primary carnitine deficiency (PCD). A retrospective study was performed in all Dutch metabolic centres, using samples from newborns and mothers referred by NBS due to low C0 concentration. Samples were included when C0 excretion and plasma C0 concentration were sampled on the same day. RatioU:P was calculated as (urine C0 [μmol/mmol creatinine])/(plasma C0 [μmol/l]). Data were available for 59 patients with genetically confirmed PCD and 68 individuals without PCD. The RatioU:P in PCD patients was significantly higher (p value < 0.001) than in those without PCD, median [IQR], respectively: 3.4 [1.2-9.5], 0.4 [0.3-0.8], area under the curve (AUC) 0.837. Classified for age (up to 1month) and without carnitine suppletion (PCD; N= 12, Non-PCD; N= 40), medians were 6.20 [4.4-8.8] and 0.37 [0.24-0.56], respectively. The AUC for RatioU:P was 0.996 with a cut-off required for 100% sensitivity at 1.7 (yielding one false positive case). RatioU:P accurately discriminates between positive and false positive newborn referrals for PCD by NBS. RatioU:P is less effective as a discriminative tool for PCD in adults and for individuals that receive carnitine suppletion.

POS-331 L-carnitine ameliorates diabetic kidney disease by alleviating mitochondrial abnormality and fatty acid accumulation in SDT-fatty rats

Abnormal fatty acid metabolism is associated with the progression of diabetic kidney disease (DKD). Carnitine plays a central role in fatty acid β-oxidation and energy production by transporting long-chain fatty acids from the cytoplasm to the mitochondria. Recently, we found that significant ectopic fat was accumulated in the kidney tissue in DKD patients compared with those in minimal change kidney disease patients independent of proteinuria levels, suggesting the abnormal carnitine dynamics in DKD. Juvenile visceral steatosis (jvs) mice, described as an animal model for systemic carnitine deficiency caused by a mutation in slc22a5 gene, introduce a marked ectopic fat accumulation in the kidney. These findings suggest that abnormal carnitine dynamics in DKD cause ectopic fat accumulation due to abnormality of the fatty acid metabolism. However, the association between abnormalities of carnitine metabolism and the progression of DKD is unknown. Therefore, we investigated the kinetics of carnitine and the effect of L-carnitine therapy in type 2 DKD model rats. Spontaneously Diabetic Torii (SDT) fatty rat, an obese type 2 diabetic model was used. Unilateral nephrectomy was performed and 0.3% salt water was administered at 6 weeks of age, and created a renal dysfunction model in SDT fatty rat (DKD model). Age-matched male Sprague-Dawley (SD) rat was used as a control. Experiment 1: We compared 3 groups; ①SD rats (n=8) ②SDT fatty rats (n=8) ③DKD rats (n=8). Experiment 2: We compared 3 groups; ①SD rats with sham operation (n=8) ②DKD rats (n=7) ③DKD rats treated with L-carnitine administration (0.75% L-carnitine diet) for 10 weeks (n=6). All rats were sacrificed at 17 weeks old. Carnitine was measured by the enzyme cycling method. Acylcarnitine was analyzed by the tandem-mass spectrometry. Plasma and renal free carnitine levels were significantly decreased and long-chain acylcarnitine levels were significantly increased in DKD rats compared with those in SD and SDT fatty rats. The renal expression levels of organic cation / carnitine transporter 2 (OCTN2), carnitine palmitoyl transferase 1a (CPT1a), CPT2 and carnitine acetyltransferase (CrAT) were significantly decreased in DKD rats compared with those in SD and SDT fatty rats. Similarly, acetyl-CoA carboxylase (ACC) activity was significantly increased and peroxisome proliferator-activated receptor γ co-activator 1α (PGC1α) and peroxisome proliferator-activated receptor α (PPARα) activity were decreased in DKD rats. Further, marked ectopic fat accumulation in the renal tubules and glomeruli in DKD model rats was observed. L-carnitine administration significantly improved renal function, urinary albumin excretion, interstitial fibrosis and renal ectopic fat accumulation in DKD model rats. L-carnitine administration ameliorated the decrease of renal OCTN2, CPT1a, CPT2 and CrAT protein expression, and significantly improved ACC, PGC1α, and PPARα activity in DKD model rats. Furthermore, L-carnitine administration mitigated lipid peroxidation and mitochondrial dysfunction in DKD rats Abnormal carnitine kinetics and dynamics might play an important role in the progression of DKD. L-carnitine administration might be a promising therapeutic strategy for improving renal function by alleviating mitochondrial dysfunction in DKD rat model.

The use of metabolomics tools in the evaluation of the fattening performance of lambs

This study aimed to determine the metabolomic characteristics associated with the fattening performance of the Awassi lamb breed under intensive fattening for 90 days. Twenty-four lambs were used in the research. The lambs were divided into two groups according to their fattening performance (good fattening performance, n = 12, and poor fattening performance, n = 12), and their metabolomic properties were evaluated. The differences between the two research groups in the amino acids of alloisoleucine, aspartic acid, histidine, hydroxylysine, isoleucine, lysine, methionine, phenylalanine, tryptophan, valine, and 1-methylhistidine were found to be statistically significant (P ≤ 0.001). Moderately significant negative correlations were found between daily concentrate feed intake and 3-methylhistidine (r = −0.469; P = 0.021), hydroxylysine (r = −0.408; P = 0.048), and serotonin (r= −0.467; P = 0.021); as well as between the average daily weight gain (ADWG) and alloisoleucine (r = −0.528; P = 0.008), 3-methylhistidine (r = −0.440; P = 0.032), and hydroxylysine (r = −0.577; P = 0.003). A moderate positive correlation was found between hydroxyisovalerylcarnitine and ADWG (r = 0.476; P = 0.019), and a negative correlation was found between hydroxyisovalerylcarnitine and the feed conversion ratio (r = −0.430; P = 0.036). Pathway analysis revealed that the most important biological pathway was the phenylalanine, tyrosine, and tryptophan biosynthesis pathway. The results of the research reveal the potential for plasma free amino acid and carnitine profiles to be used as candidate biomarkers in the evaluation of fattening performance in lambs.

A clinically validated method to separate and quantify underivatized acylcarnitines and carnitine metabolic intermediates using mixed-mode chromatography with tandem mass spectrometry

Acylcarnitines are intermediate metabolites of the mitochondria that serve as biomarkers for inherited disorders of fatty acid oxidation and amino acid metabolism. The prevailing clinical method used to quantify acylcarnitines involves flow-injection tandem mass spectrometry, an approach with a number of limitations; foremost the inability to separate and therefore distinguish key isobaric acylcarnitine species. To address these issues, we report a clinically validated liquid chromatography tandem mass spectrometry method to quantify acylcarnitines, free carnitine, and carnitine metabolic intermediates in human plasma. Importantly, this method resolves clinically relevant isobaric and isomeric acylcarnitine species in a single 22 min analysis without the use of ion pairing or derivatization reagents. This unique combination of features is not achievable by existing acylcarnitine methods and is made possible by the use of a novel mixed-mode chromatographic separation. Further clinical validation studies demonstrate excellent limits of quantification, linearity, accuracy, and inter-assay precision for analyses of 38 different calibrated analytes. An additional 28 analytes are semi-quantitatively analyzed using surrogate calibrators. The study of residual patient specimens confirms the clinical utility of this method and suggests expanded applicability to the diagnosis of peroxisomal disorders. In summary, we report a clinically validated acylcarnitine method that utilizes a novel mixed-mode chromatographic separation to provide a number of advantages in terms of specificity, accuracy, sample preparation time, and clinical utility.

3-Methylglutaconic aciduria in carriers of primary carnitine deficiency

The etiology of secondary 3-methylglutaconic aciduria (3-MGA-uria) is not well understood although is thought to be a marker of mitochondrial dysfunction. For this reason, suspicion for a secondary 3-MGA-uria often leads to an extensive clinical and laboratory work-up for mitochondrial disease, although in many cases evidence for mitochondrial dysfunction is never found.3-methylglutaconic aciduria in healthy individuals without known metabolic disease has not been well described. Here, we describe clinical and biochemical features of 23 individuals evaluated at the Greenwood Genetic Center for low plasma free carnitine reported on newborn screening. Of the 23 individuals evaluated, four individuals were diagnosed with primary carnitine deficiency, 16 were identified as carriers for primary carnitine deficiency, and three individuals were determined to be unaffected non-carriers based on molecular and biochemical testing.Elevated 3-MGA (>20 mmol/mol of creatinine) was identified in nine carriers of primary carnitine deficiency, while all unaffected non carriers and all affected individuals with primary carnitine deficiency had a normal 3-MGA level (<20 mmol/mol of creatinine). Average 3-MGA among all carriers was 39.66 mmol/mol of creatinine. Average plasma free carnitine in among all carriers (n = 16) was 13.87 μm/L, and average plasma free carnitine was not significantly different between carriers with and those without elevated 3-MGA (p = 0.66).In summary, we describe elevated 3-MGA as a discriminatory feature in nine healthy carriers of primary carnitine deficiency. Our findings suggest that heterozygosity for pathogenic alterations on SLC22A5 should be considered in the differential for individuals with persistent 3-MGA-uria of unclear etiology.

Limited Impact of Pivalate-Induced Secondary Carnitine Deficiency on Hepatic Transcriptome and Hepatic and Plasma Metabolome in Nursery Pigs.

Administration of pivalate has been demonstrated to be suitable for the induction of secondary carnitine deficiency (CD) in pigs, as model objects for humans. In order to comprehensively characterize the metabolic effects of secondary CD in the liver of pigs, the present study aimed to carry out comparative analysis of the hepatic transcriptome and hepatic and plasma metabolome of a total of 12 male 5-week-old pigs administered either pivalate (group PIV, n = 6) or vehicle (group CON, n = 6) for 28 days. Pigs of group PIV had approximately 40–60% lower concentrations of free carnitine and acetylcarnitine in plasma, liver and different skeletal muscles than pigs of group CON (p < 0.05). Transcript profiling of the liver revealed 140 differentially expressed genes (DEGs) between group PIV and group CON (fold change > 1.2 or <−1.2, p-value < 0.05). Biological process terms dealing with the innate immune response were found to be enriched with the DEGs (p < 0.05). Using a targeted metabolomics approach for the simultaneous quantification of 630 metabolites, 9 liver metabolites and 18 plasma metabolites were identified to be different between group PIV and group CON (p < 0.05). Considering the limited alterations of the hepatic transcriptome and of the liver and plasma metabolome, it can be concluded that pivalate-induced secondary CD is not associated with significant hepatic metabolism changes in pigs.

Effect of levocarnitine supplementation on myocardial strain in children with acute kidney injury receiving continuous kidney replacement therapy: a pilot study.

Carnitine plays a key role in energy production in the myocardium and is efficiently removed by continuous kidney replacement therapy (CKRT). Effects of levocarnitine supplementation on myocardial function in children receiving CKRT have not been investigated. This controlled pilot cohort study of 48 children investigated effects of levocarnitine supplementation on myocardial strain in children receiving CKRT for acute kidney injury (AKI). Children (n = 9) with AKI had total (TC) and free plasma carnitine (FC) measurements and echocardiogram for longitudinal and circumferential strain at baseline (prior to CKRT) and follow-up (on CKRT for > 1 week with intravenous levocarnitine supplementation, 20 mg/kg/day). Intervention group was compared with three controls: (1) CKRT controls (n = 10) received CKRT > 1 week (+AKI, no levocarnitine), (2) ICU controls (n = 9) were parenteral nutrition-dependent for > 1 week (no AKI, no levocarnitine), and (3) healthy controls (n = 20). In the Intervention group, TC and FC increased from 36.0 and 18 μmol/L to 93.5 and 74.5 μmol/L after supplementation. TC and FC of unsupplemented CKRT controls declined from 27.2 and 18.6 μmol/L to 12.4 and 6.6 μmol/L, which was lower vs. ICU controls (TC 32.0, FC 26.0 μmol/L), p < 0.05. Longitudinal and circumferential strain of the Intervention group improved from - 18.5% and - 18.3% to - 21.1% and - 27.6% after levocarnitine supplementation; strain of CKRT controls (-14.4%, -20%) remained impaired and was lower vs. Intervention and Healthy Control groups at follow-up, p < 0.05. Levocarnitine supplementation is associated with repletion of plasma carnitine and improvement in myocardial strain and may benefit pediatric patients undergoing prolonged CKRT.

Evaluation of Plasma Free Amino Acid and Carnitine Levels in Patients with Cesarean Scar Pregnancy.

This study aimed to explore the plasma free amino acid (FAA) and carnitine levels in pregnant women with cesarean scar pregnancy (CSP), and to compare them with those of healthy pregnant women. This prospective and randomized controlled study was conducted in patients admitted to Harran University Medical Faculty Hospital Obstetrics Clinic between January 2018 and January 2019. A total of 60 patients were included in the study, and the patients were divided into two groups: the CSP group (n = 30) and the healthy pregnant group as the control group (n = 30). The blood samples were taken from the participants between 7 - 12 weeks of gestation. Twenty-seven carnitines and their esters and 14 FAAs were analysed by liquid chromatography - mass spectrometry (LC-MS/MS). The mean plasma concentrations of some carnitines, including C2, C5, C5-OH, C5-DC, C6, C8-1, C12, C14, C14-1, C14-2, C16, C16-1, C18, and C18-1 were significantly higher in the CSP group than in the control group. However, other carnitines, including C0, C3, C4, C4-DC, C5- 1, C6-DC, C8, C8-DC, C10, C10-1, C18-1-OH, and C18-2, were similar in both groups. The plasma levels of some FAAs, including Methyl Glutaryl, Leu, Met, Phe, Arg, Orn, and Glu values, were significantly higher in the CSP group than in the control group. However, there was no statistical significance in other FAA levels, including Val, Asa, Tyr, Asp, Ala, Cit, and Gly between the two groups. Additionally, Pearson's correlation analysis showed that there were significantly positive correlations between many FAA and carnitine values. Since several plasma carnitines and FAA levels were higher in the CSP group than in the control group, we think that scar pregnancy increases the metabolic need for myometrial invasion. Also, we think that these results may be useful in clinical practice for CSP diagnosis.

L-carnitine infusion does not alleviate lipid-induced insulin resistance and metabolic inflexibility.

BackgroundLow carnitine status may underlie the development of insulin resistance and metabolic inflexibility. Intravenous lipid infusion elevates plasma free fatty acid (FFA) concentration and is a model for simulating insulin resistance and metabolic inflexibility in healthy, insulin sensitive volunteers. Here, we hypothesized that co-infusion of L-carnitine may alleviate lipid-induced insulin resistance and metabolic inflexibility.MethodsIn a randomized crossover trial, eight young healthy volunteers underwent hyperinsulinemic-euglycemic clamps (40mU/m2/min) with simultaneous infusion of saline (CON), Intralipid (20%, 90mL/h) (LIPID), or Intralipid (20%, 90mL/h) combined with L-carnitine infusion (28mg/kg) (LIPID+CAR). Ten volunteers were randomized for the intervention arms (CON, LIPID and LIPID+CAR), but two dropped-out during the study. Therefore, eight volunteers participated in all three intervention arms and were included for analysis.ResultsL-carnitine infusion elevated plasma free carnitine availability and resulted in a more pronounced increase in plasma acetylcarnitine, short-, medium-, and long-chain acylcarnitines compared to lipid infusion, however no differences in skeletal muscle free carnitine or acetylcarnitine were found. Peripheral insulin sensitivity and metabolic flexibility were blunted upon lipid infusion compared to CON but L-carnitine infusion did not alleviate this.ConclusionAcute L-carnitine infusion could not alleviated lipid-induced insulin resistance and metabolic inflexibility and did not alter skeletal muscle carnitine availability. Possibly, lipid-induced insulin resistance may also have affected carnitine uptake and may have blunted the insulin-induced carnitine storage in muscle. Future studies are needed to investigate this.

Primary carnitine deficiency in two sisters with intractable epilepsy and reversible metabolic cardiomyopathy: Two case reports.

Primary carnitine deficiency (PCD) is a disorder of the carnitine cycle that results in defective fatty acid oxidation. When carnitine cannot be transported into the cells, fatty acid oxidation is impaired, resulting a variety of symptoms, such as chronic muscle weakness, cardiomyopathy, hypoglycemia and liver dysfunction. The clinical manifestations and outcomes of different cases with PCD vary among patients. The present case report focused on two sisters with PCD. The younger sister presented with intractable epilepsy, and the older sister presented with reversible metabolic cardiomyopathy. Potential mutations in the SLC22A5 gene were investigated within the family, and a nonsense mutation [c.760C>T (p.R254X)] was identified in four family members. The two sisters harbored homozygous mutations, whereas their parents presented heterozygous mutations. Metabolic disease screening revealed low plasma free carnitine levels (<5 µmol/l) in the two sisters. The plasma free carnitine levels of their parents were normal, and they were asymptomatic. PCD in the two patients was managed using oral levocarnitine. The metabolic cardiomyopathy of the older sister improved following 3 months of treatment. However, the epilepsy of the younger sister was recurrent with oral antiepileptic therapy lasting one year and eight months, and epilepsy was finally controlled following right cerebral resection. The present case report demonstrated that the clinical manifestations presented by patients with PCD within the same family were different. The results indicated that treatment with levocarnitine supplementation should be initiated as soon as possible before irreversible organ damage occurs. In addition, metabolic decompensation and cardiac muscle functions were improved following carnitine supplementation. The resection of the severely diseased unilateral brain combined with carnitine supplementation and antiepileptic therapy may be an effective treatment for PCD with intractable epilepsy complications.