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Urea cycle disorders: Management

INTRODUCTION

The urea cycle is the metabolic pathway that transforms nitrogen to urea for excretion from the body (figure 1). Deficiency of an enzyme in the pathway causes a urea cycle disorder (UCD). The urea cycle disorders are:

  • Carbamoyl phosphate synthetase I (CPSI) deficiency (MIM #237300)
  • Ornithine transcarbamylase (OTC) deficiency (MIM #311250)
  • Argininosuccinate synthetase (ASS) deficiency (also known as classic citrullinemia or type I citrullinemia, CTLN1, MIM #215700)
  • Argininosuccinate lyase (ASL) deficiency (also known as argininosuccinic aciduria, MIM #207900)
  • N-acetyl glutamate synthetase (NAGS) deficiency (MIM #237310)
  • Arginase deficiency (also known as argininemia, MIM #207800)

UCDs, except for arginase deficiency, result in hyperammonemia and life-threatening illnesses. Survivors of the metabolic decompensation frequently have severe neurologic injury that correlates with the cumulative duration of hyperammonemia. Prompt recognition and treatment are needed to improve outcome.

The management of urea cycle disorders is discussed here. The clinical features and diagnosis of urea cycle disorders are discussed separately. A general overview of inborn errors of metabolism is also presented separately. (See "Urea cycle disorders: Clinical features and diagnosis" and "Inborn errors of metabolism: Classification" and "Inborn errors of metabolism: Epidemiology, pathogenesis, and clinical features" and "Inborn errors of metabolism: Metabolic emergencies".)

INITIAL MANAGEMENT

Neurologic abnormalities and impaired cognitive function are significantly correlated with the duration of hyperammonemia and encephalopathy [1,2]. Thus, treatment should be initiated as soon as a UCD is suspected and should proceed concurrently with the diagnostic evaluation [3-6]. (See "Urea cycle disorders: Clinical features and diagnosis", section on 'Diagnosis'.)

                   

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Literature review current through: Apr 2013. | This topic last updated: Mar 26, 2013.
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