Dietary management of urea cycle disorders: European practice

Mol Genet Metab. 2013 Dec;110(4):439-45. doi: 10.1016/j.ymgme.2013.09.003. Epub 2013 Sep 12.


Background: There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries.

Methods: Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1 Sweden) was collected by questionnaire describing management of patients with UCD on prescribed protein restricted diets.

Results: Data for 464 patients: N-acetylglutamate synthase (NAGS) deficiency, n=10; carbamoyl phosphate synthetase (CPS1) deficiency, n=29; ornithine transcarbamoylase (OTC) deficiency, n=214; citrullinaemia, n=108; argininosuccinic aciduria (ASA), n=80; arginase deficiency, n=23 was reported. The majority of patients (70%; n=327) were aged 0-16y and 30% (n=137) >16y. Prescribed median protein intake/kg body weight decreased with age with little variation between disorders. The UK tended to give more total protein than other European countries particularly in infancy. Supplements of essential amino acids (EAA) were prescribed for 38% [n=174] of the patients overall, but were given more commonly in arginase deficiency (74%), CPS (48%) and citrullinaemia (46%). Patients in Germany (64%), Portugal (67%) and Sweden (100%) were the most frequent users of EAA. Only 18% [n=84] of patients were prescribed tube feeds, most commonly for CPS (41%); and 21% [n=97] were prescribed oral energy supplements.

Conclusions: Dietary treatment for UCD varies significantly between different conditions, and between and within European IMD centres. Further studies examining the outcome of treatment compared with the type of dietary therapy and nutritional support received are required.

Keywords: Branch chain amino acids (BCAA); Essential amino acids (EAA); Metabolic; Protein restricted diet; Urea cycle disorders (UCD).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Amino Acids, Essential / metabolism*
  • Amino-Acid N-Acetyltransferase / deficiency
  • Arginase / metabolism
  • Argininosuccinic Aciduria / diet therapy
  • Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor / deficiency
  • Child
  • Child, Preschool
  • Citrullinemia / diet therapy
  • Diet, Protein-Restricted*
  • Europe
  • Humans
  • Infant
  • Infant, Newborn
  • Ornithine Carbamoyltransferase / metabolism
  • Surveys and Questionnaires
  • Treatment Outcome
  • Urea Cycle Disorders, Inborn / diet therapy*
  • Urea Cycle Disorders, Inborn / enzymology
  • Urea Cycle Disorders, Inborn / pathology*


  • Amino Acids, Essential
  • Ornithine Carbamoyltransferase
  • Amino-Acid N-Acetyltransferase
  • Arginase
  • Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor
  • carbamoyl phosphate synthetase (arginine-specific)