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. 2022 Jul 2;14(13):2755. doi: 10.3390/nu14132755

Table 1.

Causes of hyperammonaemia.

Genetic Aetiologies Non-Genetic Aetiologies
Defects of the urea cycle
  • -

    N-acetylglutamate synthase (NAGS)

  • -

    Carbamoyl phosphate synthetase 1 (CPS1)

  • -

    Ornithine transcarbamylase (OTC)

  • -

    Argininosuccinate synthase (ASS; citrullinemia type 1)

  • -

    Argininosuccinate lyase (ASL; argininosuccinic aciduria)

  • -

    Arginase (ASA; argininemia)

  • -

    Hyperornithinemia-hyperammonaemia-homocitrullinuria (HHH syndrome)

  • -

    Citrin (citrullinemia type 2)

Organic Acidemias:
  • -

    Propionic acidaemia

  • -

    Methylmalonic acidaemia

  • -
    Dibasic aminoacidurias
    • Type 1
    • Type 2 (Lysinuric protein intolerance)
  • -

    Isovaleric and 3-methylcrotonic aciduria

  • -

    Multiple acyl-CoA dehydrogenase (MADD; Glutaric aciduria type II)

  • -

    3-hydroxy-3-methylglutaric aciduria

  • -

    Multiple carboxylase deficiency

Other enzymatic deficiencies:
  • -

    Pyrroline-5-carboxylate synthetase

  • -

    Carbonic anhydrase

  • -

    Pyruvate carboxylase

  • -

    Mitochondrial fatty acid β-oxidation

  • -

    Persistent hyperinsulinemia-hyperammonaemia

  • -

    Mitochondrial defects

  • -

    Gyrate atrophy

 Drugs
  • -

    Anticonvulsants (valproate, carbamazepine, topiramate, lamotrigine, primidone, zonisamide).

  • -

    Cancer treatments (5-fluorouracil, cytarabine, vincristine, etoposide, L-asparaginase, cyclophosphamide, sunitinib, rituximab, regorafenib)

  • -

    Steroids (high doses)

  • -

    Narcotics

  • -

    Anaesthetics (enflurane, halothane)

  • -

    Barbiturates

  • -

    Haloperidol

  • -

    Salicylates

  • -

    Diuretics (acetazolamide)

  • -

    Ribavirin

  • -

    Tranexamic acid

  • -

    Glycine gel for prostate surgery

Surgeries:
  • -

    Transplants (liver, lung, kidney, bone marrow)

  • -

    Gastric surgeries (gastric bypass, bariatric surgery)

  • -

    Urinary tract surgeries (ureterosigmoidostomy, prostate resection)

 Liver function related
  • -

    Severe liver failure

  • -

    Transient hyperammonaemia of the newborn

  • -

    Portosystemic shunt

  • -

    Reye’s syndrome

Nutrition related
  • -

    Enteral/ parenteral nutrition (if low in arginine)

  • -

    Refeeding syndrome

  • -
    Severe catabolic state
    • severe malnutrition,
    • competitive muscle exercise,
    • prolonged or repetitive seizures
    • multiple myeloma and other tumours
Infections
  • -

    Urealytic germ urinary infection

  • -

    Bacterial overgrowth

  • -

    Mucositis

  • -

    COVID

Other
  • -

    Shock and/or dehydration

  • -

    Gastrointestinal bleeding

  • -

    Distal renal tubular acidosis

  • -

    Urinary tract dilatation

  • -

    Alcohol

  • -

    Hypoglycin intoxication