{
  "abstract": "Background and Importance Ornithine transcarbamylase deficiency (OTCD) is a rare X-linked urea cycle disorder that impairs ammonia detoxification, leading to hyperammonaemia, acute liver dysfunction and potentially life-threatening metabolic encephalopathy. Late-onset forms are often misdiagnosed due to non-specific symptoms, delaying treatment. Early diagnosis and pharmacological intervention are crucial to prevent neurological damage or death.Aim and Objectives To describe the clinical management of a paediatric patient with late-onset OTCD and highlight the therapeutic role of hospital pharmacists in metabolic decompensations.Material and Methods An 11-year-old male was admitted with vomiting, somnolence, and hyperammonaemia (480 µmol/L), alongside hyperlactacidaemia and hepatic dysfunction, with no relevant family history. On admission, he received hydroxocobalamin, biotin, and cerebral oedema management. Continuous veno-venous haemodiafiltration (CVVHDF) was initiated as an extracorporeal technique to achieve a rapid decrease in ammonia levels. Initial pharmacological therapy included sodium benzoate with sodium phenylacetate (alternated with phenylbutyrate), arginine, carnitine, carglumic acid, L-citrulline, paromomycin, and lactulose. Phenylbutyrate was discontinued due to nasogastric tube obstruction and replaced by sodium benzoate with phenylacetate. The hospital pharmacist adjusted and validated parenteral nutrition with protein restriction, compensated by higher carbohydrate intake to promote anabolism and protein synthesis, and provided basal fat to meet energy needs without overloading metabolism or causing acidosis/stress.Results CVVHDF rapidly reduced ammonia levels with clinical improvement, and pharmacological therapy helped maintain stable ammonia levels. Although genetic results were not yet available, diagnosis was supported by metabolic findings: marked elevation of urinary orotic acid, elevated glutamine, and decreased citrulline, leading to clinical suspicion of OTCD. Genetic testing later confirmed a hemizygote OTC gene mutation. Maternal testing revealed mutation G4A1V3, despite an uncomplicated pregnancy and delivery. Therapy was adjusted for outpatient management, maintaining phenylbutyrate, citrulline, and strict protein control. Regular monitoring of ammonia, amino acids, and liver enzymes was implemented. The patient remained stable, with no further metabolic decompensations and good adherence to treatment.Conclusion and Relevance OTCD can occur beyond the neonatal period with subtle or non-specific symptoms, delaying diagnosis. Early multidisciplinary intervention, including metabolic specialists and hospital pharmacists–who play a key role in the rapid initiation and adjustment of therapy and parenteral nutrition–is essential to secure favourable outcomes and avoid irreversible neurological damage.Conflict of Interest No conflict of interest",
  "authors": [
    {
      "affiliations": [
        "Hospital Universitario La Paz, Pharmacy Department, Madrid, Spain"
      ],
      "name": "ME Ibáñez Ronco"
    },
    {
      "affiliations": [
        "Hospital Universitario La Paz, Pharmacy Department, Madrid, Spain"
      ],
      "name": "AB Arancón Pardo"
    },
    {
      "affiliations": [
        "Hospital Universitario La Paz, Pharmacy Department, Madrid, Spain"
      ],
      "name": "C Jiménez Nuñez"
    },
    {
      "affiliations": [
        "Hospital Universitario La Paz, Pharmacy Department, Madrid, Spain"
      ],
      "name": "A Herrero Ambrosio"
    }
  ],
  "title": "4CPS-063 Late-onset ornithine transcarbamylase deficiency in a paediatric patient: successful management of a metabolic emergency –a case report",
  "uid": "35cd0bcd-6b4a-5122-a635-c6ef998fb286"
}