Introduction to the organic acidemias
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop in Atlas of Inherited Metabolic Diseases, 2020
Initial laboratory evaluation involves tests that are readily available in most clinical chemistry laboratories. Most important in early discrimination are the electrolytes and the ammonia. Blood gases are often the first data available in a very sick infant. Acidosis and hyperammonemia are indicative of an organic acidemia. In contrast, a patient with a urea cycle defect has hyperammonemia and alkalosis. It is important not to delay treatment of acidosis in the belief that the problem is a urea cycle defect. Hyperammonemia regardless of cause must be treated. Hypocalcemia may be a nonspecific harbinger of metabolic disease. Elevated levels of lactate in the absence of cardiac disease, shock or hypoxemia are often seen in organic acidemias as well as in the lactic acidemias of mitochondrial disease. The blood count is useful in indicating the presence or absence of infection. More important, neutropenia with or without thrombocytopenia or even with pancytopenia is characteristic of organic acidemia.
Maple Syrup Urine Disease (MSUD)
Charles Theisler in Adjuvant Medical Care, 2023
Maple syrup urine disease is an inherited disorder that affects branched-chain amino acids. It is one type of organic acidemia. The condition gets its name from the distinctive sweet odor that emanates from an affected infant's urine. This disorder is
Two cases of glutaric aciduria type II: how to differentiate from inflammatory myopathies?
Published in Acta Clinica Belgica, 2019
Meltem Koca, Abdulsamet Erden, Berkan Armagan, Alper Sari, Fatih Yildiz, Sevim Ozdamar, Umut Kalyoncu, Omer Karadag
The clinical presentation is heterogeneous and can be grouped into three forms: the neonatal-onset form with and without congenital anomalies (type 1 and 2, respectively), and the late-onset form (type 3) [1]. Severity of the clinical picture is not related to the gene which is affected (ETFA, ETFB or ETFDH), rather it depends on the nature and the location of the mutation [2]. The neonatal-onset forms are usually fatal in perinatal period and present with acute metabolic decompensations characterized by severe metabolic acidosis, nonketotic hypoglycemia, hypotonia, multisystem involvement with or without congenital anomalies which include facial dysmorphism, cystic renal dysplasia, and cerebral malformations and even coma [3]. Age and symptoms at presentation are highly variable in the late onset form and are characterized by recurrent episodes of lethargy, vomiting, hypoglycemia, metabolic acidosis, and chronic manifestations of lipid storage myopathy: myalgia, muscle weakness and exercise intolerance. Organic aciduria may be mild, atypical, or detectable only during acute metabolic decompensations [4].
Diagnostic challenges in metabolic myopathies
Published in Expert Review of Neurotherapeutics, 2020
Corrado Angelini, Roberta Marozzo, Valentina Pegoraro, Sabrina Sacconi
Most patients with primary carnitine deficiency are followed by a metabolic specialist as well as a dietician., it has been documented that the main treatment with carnitine supplementation corrects heart problems and muscle weakness [25,43] in several patients. In some cases, this treatment prevents the need for a cardiac transplant. The L – carnitine dose may vary from 100 to 600 mg/kg per day based on the calculated carnitine depletion from tissues. To adjust the dose, several plasma carnitine level measurements might be useful, Plasma carnitine levels should be monitored frequently to reduce the episodes of hypoglycemia. Side effects for L – carnitine supplementation are mild and consist of diarrhea, intestinal discomfort, or a fishy body odor. In some cases, a medium-chain triglyceride diet (MCT) may be added. Muscle carnitine clinical features affect mostly limb and neck muscles. The patients show normal ketogenesis on fasting. Diagnostic biochemical features are low muscle carnitine (below 15%) and absence of organic aciduria. There is in vitro stimulation by L-carnitine of labeled palmitate oxidation and oleate [24]. Muscle carnitine deficiency could be caused by an abnormal low – affinity carrier or by a low number of sarcolemmal carriers. It is differentiated from carnitine insufficiency in FAO disorders because of the absence of acylcarnitines elevation in plasma or urine.
Fetal hydrops – a review and a clinical approach to identifying the cause
Published in Expert Opinion on Orphan Drugs, 2020
Esther Dempsey, Tessa Homfray, John M Simpson, Steve Jeffery, Sahar Mansour, Pia Ostergaard
Barth Syndrome is an X-linked disorder of mitochondrial function and stability caused by mutations in TAZ [85]. Clinically the condition results in a dilated cardiomyopathy with endocardial fibroelastosis, which can lead to hydrops antenatally [86]. On fetal echocardiography, crypts are characteristically seen in the apex and free wall [82]. Those that survive may show growth retardation, proximal skeletal myopathy, neutropenia and organic aciduria [85,87].
Related Knowledge Centers
- Fatty Acid
- Isoleucine
- Leucine
- Methylmalonic Acidemia
- Organic Acid
- Propionic Acidemia
- Protein Metabolism
- Valine
- Amino Acid
- Inborn Errors of Metabolism