title: Macro-AST: misleading finding in an adolescent with MCAD-deficiency.
abstract: BACKGROUND
  MCAD-deficiency is the most common inborn error of fatty acid oxidation now included in many newborn screening programms using MS/MS. During prolonged catabolic episodes, patients may suffer from metabolic decompensation with dysfunction of liver, skeletal- and heart muscle as well as brain. In anabolism, neither clinical symptoms nor biochemical signs of organ dysfunction occur.
  
  
  METHODS
  We report a female patient with MCAD-deficiency in whom at the age of 11 years isolated AST-elevation was found without any clinical or biochemical signs of organ dysfunction. We showed by polyethylene glycol precipitation that macro-AST formation was responsible for this biochemical finding. AST was probably complexed with immunoglobulins possibly related to an allergic disposition. Macro-AST formation is not a special feature of MCAD-deficiency but rather a non-specific, coincidental finding which also occurs in healthy individuals. The general practitioner consulted by the patient before coming to our outpatient clinic for inborn errors of metabolism was worried that isolated AST-elevation indicated cell damage in MCAD-deficiency. He ordered further diagnostic tests like ultrasound, ECG and echocardiography without any pathology.
  
  
  CONCLUSIONS
  In isolated AST-elevation, macro-AST has to be considered in order to avoid unnecessary, costly and invasive evaluation. This is not only true for healthy persons but for patients with chronic diseases like MCAD as well.
authors.affiliation: Department of Paediatrics, Hannover Medical School, Hannover, Germany. das.anibh@mh-hannover.de
authors.forename: Anibh M
authors.initials: AM
authors.lastname: Das
authors.forename: Sabine
authors.initials: S
authors.lastname: Drache
authors.forename: Nils
authors.initials: N
authors.lastname: Janzen
authors.forename: Andreas
authors.initials: A
authors.lastname: Franke
mesh_terms: D042964:Acyl-CoA Dehydrogenase / Q000097:blood / Q000172:deficiency; D000293:Adolescent; D001219:Aspartate Aminotransferases / Q000097:blood*; D001249:Asthma / Q000097:blood / Q000201:enzymology; D004802:Eosinophilia / Q000097:blood / Q000201:enzymology; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008052:Lipid Metabolism, Inborn Errors / Q000097:blood* / Q000201:enzymology; D065631:Rhinitis, Allergic; D012221:Rhinitis, Allergic, Perennial / Q000097:blood / Q000201:enzymology
chemical_list: D007073:Immunoglobulin E; D042964:Acyl-CoA Dehydrogenase; D001219:Aspartate Aminotransferases