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Open Access Case report

Macro-AST: misleading finding in an adolescent with MCAD-deficiency

Anibh M Das1*, Sabine Drache2, Nils Janzen124 and Andreas Franke3

Author Affiliations

1 Department of Paediatrics, Hannover Medical School, Carl-Neuberg Str. 1, D-30625, Hannover, Germany

2 MVZ Labor Dr. Eberhard & Partner, Dortmund, Germany

3 Department of Internal Medicine II, Siloah Hospital, Hannover, Germany

4 Present address: Department of Neuropaediatrics, Ruhr University, Bochum, Germany

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BMC Gastroenterology 2012, 12:119  doi:10.1186/1471-230X-12-119

Published: 30 August 2012

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.

Case presentation

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.

Conclusion

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.

Keywords:
Macro-AST; MCAD-deficiency; Liver; Heart; Muscle; Immunoglobulin