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Metabolic Disorders II
Published in John F. Pohl, Christopher Jolley, Daniel Gelfond, Pediatric Gastroenterology, 2014
Tyrosinemia type I is characterized by the following biochemical findings: Increased succinlyacetone excretion in the urine of a child with liver failure or severe renal disease is pathognomonic of tyrosinemia type 1. Many laboratories require that measurement of succinylacetone be specifically requested when ordering urine organic acids.Elevated urinary concentrations of tyrosine metabolites (p-hydroxyphenylpyruvate, p-hydroxyphenyllactate, and p-hydroxyphenylacetate) detected on urinary organic acids testing.Increased urinary excretion of the compound delta-aminolevulinic acid (δ-ALA) secondary to inhibition of the enzyme δ-ALA dehydratase by succinylacetone in liver and circulating RBCs.Elevated plasma concentration of tyrosine, methionine, and phenylalanine on plasma amino acid analysis; however, elevated plasma tyrosine concentration can also be a nonspecific indicator of liver damage or immaturity.Very low or undetectable FAH enzyme activity as measured in cultured skin fibroblasts or hepatocytes. Specific reference ranges vary among laboratories.
Advances in genetic testing and optimization of clinical management in children and adults with epilepsy
Published in Expert Review of Neurotherapeutics, 2020
Marcello Scala, Amedeo Bianchi, Francesca Bisulli, Antonietta Coppola, Maurizio Elia, Marina Trivisano, Dario Pruna, Tommaso Pippucci, Laura Canafoglia, Simona Lattanzi, Silvana Franceschetti, Carlo Nobile, Antonio Gambardella, Roberto Michelucci, Federico Zara, Pasquale Striano
Standard laboratory tests should always be performed in patients with epilepsy with drug-resistant seizures, especially if developmental delay or progressive neurological deterioration is associated [22]. Indeed, a comprehensive metabolic workup might reveal an underlying metabolic condition with a possible etiology-specific treatment. An early diagnosis and a timely start of the most appropriate treatment are essential in the management of treatable metabolic epilepsy syndromes, allowing to stabilize or reverse neurological and systemic symptoms [22,23]. In particular, standard laboratory tests (blood glucose, electrolytes, and ammonia) should be supported by a first-line metabolic screening including plasma and urine amino acid levels, urine organic acids, blood spot acylcarnitine profile, and urine creatine/creatinine ratio [23]. If a specific disorder is suspected according to the patient’s electroclinical features, second-line tests can be performed. As an example, the dosage of plasma and urine biotin as well as the analysis of serum biotinidase enzyme activity may be fundamental to diagnose the underlying metabolic disorder in a child developing seizures, neuro-ophthalmological, and cutaneous manifestations in the first months of life [23]. In this case, an early diagnosis of biotinidase deficiency allows to start a prompt biotin supplementation (5–20 mg/day), which leads to seizure control, stabilization of neurological complications, and reversal of neuroradiological abnormalities [23,24].
An update on diagnosis and therapy of metabolic myopathies
Published in Expert Review of Neurotherapeutics, 2018
Urine may not only be helpful as a source of epithelial cells containing mtDNA but also for diagnostic work-up with metabolomics [23]. Most helpful urine parameters in the work-up for metabolic myopathies are the urine organic acids (ketones, dicarboxylic acids, 3-methylglutaconic acid) and the acyl-carnitines [4]. Acyl-carnitines can be particularly helpful to screen for LSD. Additionally, acyl-carnitines have been proposed as biomarkers of beta-oxidation defects (FAODs). During rhabdomyolysis, myoglobinurea may occur. In a recent study of patients with m.3243A>G-associated mitochondrial encephalopathy lactic acidosis, and stroke-like episode syndrome (MELAS), 36 perturbed metabolites were detected in the urine reflecting an altered redox state, fatty acid catabolism, and one-carbon metabolism [23]. However, stalled fatty acid oxidation prevailed as being particularly perturbed in MELAS patients [23].
A case report of methadone-associated hypoglycemia in an 11-month-old male
Published in Clinical Toxicology, 2018
Michael S. Toce, Margaret A. Stefater, David T. Breault, Michele M. Burns
Upon questioning, the mother and the father reported having a history of intravenous drug abuse and were currently receiving methadone maintenance therapy with the father having a 5-d supply at home due to years of compliance. A quantitative methadone level sent from a blood sample collected from the patient at the time of arrival to the emergency department (ED) was 123 ng/mL by quantitative liquid chromatography-tandem mass spectrometry (lower limit of detection 10 ng/mL). Metabolic evaluation, including plasma amino acids and urine organic acids, was normal. Toxicologic testing for sulfonylureas was negative. Serum and urine drug in-hospital screening, including acetaminophen, ethanol and salicylates, was otherwise negative except for positive urine benzodiazapines, which had been administered in the ED. Blood, urine, and cerebral spinal fluid cultures were negative. A respiratory culture grew Staphylococcus aureus and Klebsiella pneumonia and patient remained on ceftriaxone for 7 d.