Low Serum Carnitine Levels Research Articles

Primary Carnitine Deficiency and Autism Spectrum Disorder is there a Relationship?

Carnitine plays essential role in energy metabolism .Systemic primary carnitine deficiency is a genetic disorder caused by decreased or absent organic cation transporter type 2 (OCTN2) carnitine transporter activity, resulting in low serum carnitine levels and decreased carnitine accumulation inside cells. The decrease carnitine results in impaired fatty acid oxidation. Primary carnitine deficiency presents a hypoketotic, hypoglycemia and hepatic encephalopathy. Recently, primary carnitine deficiency has been associated with neurodevelopmental disorders including autism spectrum disorders. A seven year-old schoolgirl with intellectual deficit, autistic features and primary carnitine deficiency has been reported. A significant decrease in carnitine levels has been shown in patients with autism and this has been related to the existence of a mitochondrial disease and more severe autism. The early identification of patients with low levels of carnitine or primary carnitine deficiency, with the different methods of measuring free carnitine, including tandem mass spectrometry could help to identify these patients early and achieve an early treatment and better neurological prognosis, because autism spectrum disorders may be preventable in this subgroup. We hope that this paper is useful to neurologists and pediatricians, and may give them more reason to suspect a diagnosis of PCD and autism.

First Case Report of Primary Carnitine Deficiency Manifested as Intellectual Disability and Autism Spectrum Disorder

Systemic primary carnitine deficiency (PCD) is a genetic disorder caused by decreased or absent organic cation transporter type 2 (OCTN2) carnitine transporter activity, resulting in low serum carnitine levels and decreased carnitine accumulation inside cells. In early life, PCD is usually diagnosed as a metabolic decompensation, presenting as hypoketotic hypoglycemia, Reye syndrome, or sudden infant death; in childhood, PCD presents with skeletal or cardiac myopathy. However, the clinical presentation of PCD characterized by autism spectrum disorder (ASD) with intellectual disability (ID) has seldom been reported in the literature. In this report, we describe the clinical features of a seven-year-old girl diagnosed with PCD who presented atypical features of the disease, including a developmental delay involving language skills, concentration, and attention span, as well as autistic features and brain alterations apparent in magnetic resonance imaging. We aim to highlight the difficulties related to the diagnostic and therapeutic approaches used to diagnose such patients. The case reported here presented typical signs of PCD, including frequent episodes of hypoglycemia, generalized muscle weakness, decreased muscle mass, and physical growth deficits. A molecular genetic study confirmed the definitive diagnosis of the disease (c.1345T>G (p.Y449D)) in gene SLC22A5, located in exon 8. PCD can be accompanied by less common clinical signs, which may delay its diagnosis because the resulting global clinical picture can closely resemble other metabolic disorders. In this case, the patient was prescribed a carnitine-enriched diet, as well as oral carnitine at a dose of 100 mg/kg/day. PCD has a better prognosis if it is diagnosed and treated early; however, a high level of clinical suspicion is required for its timely and accurate diagnosis.

Renal dysfunction is rare in Fukuyama congenital muscular dystrophy

BackgroundThe leading cause of death in patients with Fukuyama congenital muscular dystrophy (FCMD) is congestive heart failure or respiratory dysfunction, which is same as that in Duchenne muscular dystrophy (DMD). Recent studies reported that renal dysfunction is a common complication and an increasing cause of death in advanced DMD. It can be attributable to circulatory instability or inappropriate use of drugs for treating cardiac dysfunction. MethodsWe retrospectively evaluated renal function in 38 genetically diagnosed patients with FCMD (range, 1.3–32.9 years; mean age, 13.7 ± 6.9 years) using cystatin C. We examined possible relationships of cystatin C with blood natriuretic peptide and creatinine levels along with cardiac echocardiography findings. ResultsTwenty-five patients were treated for cardiac dysfunction. Elevated cystatin C level was detected only in two, who also showed proteinuria, glycosuria, hematuria, and extremely high β2-microglobulin levels on urine tests, and were thus diagnosed with renal tubular cell damage. Because both patients were treated for intractable epilepsy with various antiepileptic drugs, including valproic acid (VPA), and had low serum carnitine levels, renal tubular cell damage was considered as an adverse effect of VPA. Unlike patients with DMD, no patient with FCMD had renal dysfunction. Such a rare occurrence of renal dysfunction can be attributable to mild cardiac dysfunction, short disease duration, and careful and early fluid management. ConclusionRenal dysfunction is rare in patients with FCMD; however, renal tubular cell damage should be ascertained, particularly in those undergoing VPA treatment for epilepsy.

Carnitine transport and fatty acid oxidation

Carnitine is essential for the transfer of long-chain fatty acids across the inner mitochondrial membrane for subsequent β-oxidation. It can be synthesized by the body or assumed with the diet from meat and dairy products. Defects in carnitine biosynthesis do not routinely result in low plasma carnitine levels. Carnitine is accumulated by the cells and retained by kidneys using OCTN2, a high affinity organic cation transporter specific for carnitine. Defects in the OCTN2 carnitine transporter results in autosomal recessive primary carnitine deficiency characterized by decreased intracellular carnitine accumulation, increased losses of carnitine in the urine, and low serum carnitine levels. Patients can present early in life with hypoketotic hypoglycemia and hepatic encephalopathy, or later in life with skeletal and cardiac myopathy or sudden death from cardiac arrhythmia, usually triggered by fasting or catabolic state. This disease responds to oral carnitine that, in pharmacological doses, enters cells using the amino acid transporter B0,+. Primary carnitine deficiency can be suspected from the clinical presentation or identified by low levels of free carnitine (C0) in the newborn screening. Some adult patients have been diagnosed following the birth of an unaffected child with very low carnitine levels in the newborn screening. The diagnosis is confirmed by measuring low carnitine uptake in the patients' fibroblasts or by DNA sequencing of the SLC22A5 gene encoding the OCTN2 carnitine transporter. Some mutations are specific for certain ethnic backgrounds, but the majority are private and identified only in individual families. Although the genotype usually does not correlate with metabolic or cardiac involvement in primary carnitine deficiency, patients presenting as adults tend to have at least one missense mutation retaining residual activity. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.

G.P.317: Renal dysfunction in patients with Fukuyama congenital muscular dystrophy

Fukuyama congenital muscular dystrophy (FCMD), characterized by intellectual deficits and epilepsy with cortical migration defects, is the most common congenital muscular dystrophy in Japan. Most patients die of congestive heart failure or respiratory dysfunction, as in Duchenne muscular dystrophy (DMD), in the second decade of life. Recent studies have found that renal dysfunction is a common complication of advanced DMD and is the third leading cause of death in these patients. Circulatory instability caused by cardiac dysfunction is thought to result in renal dysfunction, especially prerenal failure. We retrospectively evaluated renal function in 37 genetically diagnosed FCMD patients (1.3–32.9 years, mean age 13.7 ± 6.9 years) using Cystatin C. We examined possible relationships of Cystatin with the levels of blood natriuretic peptide and creatinine, as well as the cardiac echo results. Twenty-four patients were treated for cardiac dysfunction, but elevated Cystatin C was detected in only two. These two patients also showed proteinuria, glycosuria, hematuria and extremely high levels of β2-microglobulin on urine tests and were thus diagnosed as having kidney tubule cell damage. Since both patients were treated for intractable epilepsy with many types of antiepileptic drugs, including valproic acid (VPA), and had low serum carnitine levels, kidney tubule cell damage was thought to be an adverse effect of VPA. One patient improved in response to a reduced VPA dose, but the other developed Fanconi syndrome. Unlike DMD patients, none of our FCMD patients progressed to prerenal failure. Though FCMD patients also have cardiac dysfunction, careful fluid management is instituted early because dysphagia emerges in the early stage. In DMD patients, inadequate fluid management may also cause circulatory instability, which can progress to prerenal failure. On the other hand, kidney tubule cell damage should be noted in FCMD patients especially with VPA treatment for epilepsy.

Serum carnitine levels and levocarnitine supplementation in institutionalized Huntington’s disease patients

Along with antioxidant properties, carnitine is an important regulator of lipid metabolism in humans. While beneficial effects of carnitine have been demonstrated in animal models of Huntington's disease (HD), metabolism of carnitine has not been studied in humans with this illness. In this retrospective database review from 23 patients admitted to a HD-specialized nursing home unit, we found a relatively high prevalence of hypocarnitinemia (6 cases, 26%). Our review suggests that catabolism and chronic valproate use predisposed our patients to develop hypocarnitinemia. The patients with low serum carnitine levels who received levocarnitine supplementation, during a mean period of 7.3 months, showed improvement in motor, cognitive and behavioral measures. We hypothesize that observed improvement related to the resolution of reversible metabolic encephalopathy and myopathy associated with secondary carnitine deficiency. In conclusion, notwithstanding its limitations, this is the first study to report measurements of carnitine levels in HD patients, revealing relatively high prevalence of hypocarnitinemia in our population. Our findings suggest that HD patients with hypocarnitinemia may benefit from low-dose levocarnitine supplementation. Further studies of carnitine metabolism and supplementation in HD patients are warranted.

L‐carnitine and cancer cachexia: Clinical and experimental aspects

Cancer cachexia is a multifaceted syndrome characterized, among many symptoms, by extensive muscle wasting. Chronic systemic inflammation, partly triggered and sustained by cytokines, as well as increased oxidative stress contributes to the pathogenesis of this complex metabolic disorder. l-carnitine plays a central role in the metabolism of fatty acids and shows important antioxidant and anti-inflammatory properties. Systemic carnitine depletion has been described in several diseases, and it is characterized by fatigue, muscle weakness, and decreased tolerance to metabolic stress. In cachectic cancer patients, low serum carnitine levels have been reported, and this change has been suggested to play an important contributory role in the development of cachexia. Based on these data, carnitine supplementation has been tested in preliminary studies concerning human cachexia, resulting in improved fatigue and quality of life. We present here a review of clinical and experimental evidence regarding the use of carnitine supplementation in the management of cancer cachexia.

Clinical Outcomes and Low-Dose Levocarnitine Supplementation in Psychiatric Inpatients With Documented Hypocarnitinemia: A Retrospective Chart Review

Metabolic encephalopathy is one of the crucial manifestations of carnitine deficiency. In psychiatric patients, low serum carnitine levels may result from chronic valproate therapy. Despite the widespread use of valproate in psychiatry, neither carnitine deficiency nor supplementation has been studied in a psychiatric population. To describe clinical outcomes in hospitalized psychiatric patients with documented hypocarnitinemia who were receiving oral levocarnitine supplementation. Retrospective chart review. In 38 patients with hypocarnitinemia, a low-dose oral levocarnitine supplementation, in association with comprehensive psychiatric therapy, did not result in any adverse psychiatric or medical outcomes, and was associated with overall improved behavioral, cognitive, and motor functioning. Initially all patients had some degree of cognitive impairment, but after correction of carnitine serum levels, scores on the Mini-Mental State Examination (MMSE) improved in most of the patients (mean improvement 5.5 points, P <0.0001), and normalized in 11 cases. This allowed a correction of the diagnosis in 8 of 14 patients who had initially been diagnosed with dementia. African-American patients achieved significantly lower serum carnitine levels and MMSE scores than Caucasian patients with comparable therapy. We hypothesize that correction of carnitine depletion, either by levocarnitine supplementation or by valproate dose reduction, may enhance recovery from hypocarnitinemia-associated encephalopathy in psychiatric patients. Our findings also suggest that ethnic traits may affect carnitine bioavailability as well as cognitive outcomes in this clinical context. Further studies of carnitine metabolism and supplementation in psychiatric patients are warranted.

Decrease of serum carnitine levels in patients with or without gastrointestinal cancer cachexia

To evaluate the levels of serum carnitine in patients with cancer in digestive organs and to compare them with other cancers in order to provide new insights into the mechanisms of cachexia. Fifty-five cachectic patients with or without gastrointestinal cancer were enrolled in the present study. They underwent routine laboratory investigations, including examination of the levels of various forms of carnitine present in serum (i.e., long-chain acylcarnitine, short-chain acylcarnitine, free carnitine, and total carnitine). These values were compared with those found in 60 cancer patients in good nutritional status as well as with those of 30 healthy control subjects. When the cachectic patients with gastro-intestinal cancer were compared with the cachectic patients without gastrointestinal cancer, the difference was -6.8 micromol/L in free carnitine (P < 0.005), 0.04 micromol/L in long chain acylcarnitine (P < 0.05), 8.7 micromol/L in total carnitine (P < 0.001). In the cachectic patients with or without gastrointestinal cancer, the difference was 12.2 micromol/L in free carnitine (P < 0.001), 4.60 micromol/L in short chain acylcarnitine (P < 0.001), and 0.60 micromol /L in long-chain acylcarnitine (P < 0.005) and 17.4 micromol/L in total carnitine (P < 0.001). In the cachectic patients with gastrointestinal cancer and the healthy control subjects, the difference was 15.5 micromol/L in free carnitine (P < 0.001), 5.2 micromol /L in short-chain acylcarnitine (P < 0.001), 1.0 micromol/L in long chain acylcarnitine (P < 0.001), and 21.8 micromol/L in total carnitine (P < 0.001). Low serum levels of carnitine in terminal neoplastic patients are decreased greatly due to the decreased dietary intake and impaired endogenous synthesis of this substance. These low serum carnitine levels also contribute to the progression of cachexia in cancer patients.

SERUM CARNITINE LEVELS IN CHILDREN WITH IRON-DEFICIENCY ANEMIA WITH OR WITHOUT PICA

Carnitine is ingested through animal-derived foods as well as synthesized in vivo. It plays an important role in the energy metabolism of many tissues. Iron acts as a co-factor for the synthesis of carnitine. However, the importance of iron deficiency as a cause of secondary carnitine deficiency is not well established. The aim of this study was to investigate the serum levels of carnitine in children with iron-deficiency anemia compared to those of healthy children and to determine if serum carnitine levels in with or without pica differ. The mean serum carnitine concentration in the iron-deficiency group was significantly lower than that in healthy children (12.44± 5.09 and 32.48 ± 7.92 μmol/L, respectively, p <. 001). In the iron-deficient group, serum carnitine levels, ferritin levels, and other hematological parameters were lowest in patients with pica (p <. 001). Pearson correlation test indicated a positive correlation between serum carnitine and ferritin levels in iron-deficient patients. Based on the evidence about the effect of low iron on carnitine stores in animal studies, the authors propose that low serum carnitine levels in these children may be secondary to iron-deficiency anemia. However, further large-scale studies are needed to establish the frequency of carnitine deficiency in children with iron-deficiency anemia.

Serum carnitine levels in patients with tumoral cachexia

Background Cachexia is a serious complication of many cancers that is common in cancer and AIDS patients. However, the key factors and mechanisms involved in the development of cachexia are not yet understood. There is little data currently available regarding carnitine metabolism in patients with neoplasm and cachexia. Methods Forty-six neoplastic patients with different localizations of their primary disease gave signed, informed consent before enrolling in the present study. They underwent routine laboratory investigation, including examination of the levels of the various forms of carnitine present in serum (i.e., long-chain acylcarnitine, short-chain acylcarnitine, soluble acid acylcarnitine, free carnitine, and total carnitine). These values were compared with those found in 30 cancer patients in good nutritional status as well as with those of 30 healthy control subjects. Results In the comparison of serum plasma carnitine of cachectic patients versus controls, the difference in free carnitine was − 8.20 μmol/L ( p = 0.000); the difference in short-chain acylcarnitine − 2.60 μmol/L ( p = 0.029); the difference in soluble acid carnitine − 10.80 μmol/L ( p = 0.000); the difference in long-chain acylcarnitine − 0.40 μmol/L ( p = 0.036); and the difference in total carnitine −11.20 μmol/L ( p = 0.000). In the comparison of serum plasma carnitine of cachectic versus neoplastic patients in good nutritional status, the difference in free carnitine was −5.80 μmol/L ( p = 0.006); the difference in soluble acid carnitine − 7.20 μmol/L ( p = 0.000); and the difference in total carnitine − 7.50 μmol/L ( p = 0.000). Conclusion Our study showed that, in the multifactorial pathogenesis of cachexia, the low serum levels of carnitine in terminal neoplastic patients, which are due to a decreased dietary intake as well as to an impaired endogenous synthesis of this substance, could play an important role. These low serum carnitine levels may also contribute to the development of cachexia in cancer patients.

Miopatía por déficit de carnitina: un caso de diagnóstico tardío

Myopathies caused by lipidic metabolism alterations are very infrequent. Carnitine deficiency-associated myopathies are included in this group. Two main types of carnitine deficiency syndromes have been delineated: a predominantly myopathic form, with normal serum and low muscle carnitine levels, and a systemic form, with encephalopathy, hepatic dysfunction, muscle weakness and low muscle, liver and serum carnitine levels. Both types have typical lipid stores in muscle biopsy. We describe the case of a myopathic form of carnitine deficiency. Due to the age of the patient, this is an unusual case, with an unfavourable evolution. Therapeutic measures used in these patients have included prednisone, carnitine replacement and a low-fat with medium chain tryglycerides and high-carbohydrate diet. However, in none of the patients responding to therapy, a significative increase in muscle carnitine has been demonstrated.

LOW SERUM CARNITINE CONCENTRATIONS IN HEALTHY CHILDREN WITH IRON DEFICIENCY ANEMIA

Carnitine is not only obtained from animal-derived foods but also synthesized in the body. It plays an important role in the energy metabolism of many tissues, including heart and skeletal muscles. Iron is known to be essential for the biosynthesis of carnitine. Although many conditions are well known to cause secondary carnitine deficiency, iron deficiency, which is a very common condition in children, is not well studied as a cause of secondary carnitine deficiency in humans. This study demonstrates the coexistence of iron deficiency and low carnitine levels in otherwise healthy children. The mean carnitine concentration of 18 otherwise healthy children with iron deficiency anemia was significantly lower compared to the mean carnitine concentration of healthy children without iron deficiency anemia. Based on the evidence about the effect of low iron on carnitine stores in experimental animals, we proposed that low serum carnitine levels in these children may be secondary to iron deficiency. However, further studies need to be done to further clarify this relationship.

Controlled diet in phenylketonuria may cause serum carnitine deficiency

Serum carnitine levels may be reduced in patients with phenylketonuria (PKU) owing to low carnitine intake, deficient carnitine synthesis and acylcarnitine production from phenylalanine metabolites. In order to investigate the possible carnitine deficiency we determined serum carnitine in its different forms and the precursors and cofactors involved in its synthesis in a group of patients with PKU or hyperphenylalaninaemia. Free, total and acylcarnitine values were significatively reduced only in PKU patients with Phe-restricted diet which had not been supplemented with carnitine. Acylcarnitine/free carnitine ratio and all the other parameters studied were normal in all patients. We conclude that the low serum carnitine levels in PKU patients with a strict diet are a consequence of the low carnitine intake.

Valproate-Induced Coma With Ketosis and Carnitine Insufficiency

We observed two patients who developed coma following administration of valproate in dosages of 32 to 40 mg/kg per day. Valproate levels were within the therapeutic range, and results of liver function studies were normal. Both patients had ketosis and adipic aciduria. Plasma free carnitine levels were decreased during coma and after recovery. One patient excreted ethylmalonic acid, butyrylcarnitine, and glutarylcarnitine during and after resolution of coma, suggesting a multiple acyl coenzyme A dehydrogenation defect. Low serum carnitine levels may predispose patients to development of altered consciousness when treated with valproate.