NCC Knowledge Nugget Series: Amino Acidemias- Elevated Citrulline ACT Sheet-Elevated Citrulline ACT Sheet

Elevated Citrulline ACT Sheet

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The document is an ACT (Actionable Condition Targeted) sheet intended as an educational resource for medical geneticists and clinicians, particularly designed to ensure quality medical services. The adherence to this resource is voluntary, and it should not be viewed as exhaustive or exclusive of other valid procedures or tests. Clinicians are advised to exercise professional judgment based on specific clinical scenarios and to document the rationale behind chosen procedures or tests.<br /><br />**Newborn Screening for Elevated Citrulline:**<br />- **Differential Diagnosis:** Citrullinemia type I, argininosuccinic aciduria, citrullinemia type II, and pyruvate carboxylase deficiency.<br />- **Condition Description:** Disorders related to elevated citrulline typically involve urea cycle defects, leading to hyperammonemia, which can be severe and life-threatening.<br /><br />**Immediate Actions:**<br />1. Inform the family of the screening result.<br />2. Ascertain clinical status (e.g., poor feeding, vomiting, lethargy, tachypnea).<br />3. Consult a pediatric metabolic specialist the same day.<br />4. Evaluate the newborn for signs like poor feeding, lethargy, hypotonia, and seizures. Hospitalization may be required based on severity.<br />5. Initiate confirmatory testing and management as directed by the specialist.<br />6. Provide the family with basic information about potential diagnoses and management strategies.<br />7. Report the final diagnostic outcome to the newborn screening program.<br /><br />**Diagnostic Evaluation:**<br />- **Plasma Ammonia:** Markedly elevated in citrullinemia type I and less in others.<br />- **Plasma Amino Acids:** Elevated citrulline in citrullinemia type I; elevated citrulline and other amino acids in citrullinemia type II; elevated citrulline and argininosuccinic acid in argininosuccinic aciduria.<br />- **Urine Amino Acids:** Elevated argininosuccinic acid more detectable in argininosuccinic aciduria.<br />- **Molecular Genetic/Enzyme Testing:** May be required for an accurate diagnosis.<br /><br />**Clinical Considerations:**<br />Citrullinemia and argininosuccinic aciduria may present acutely in newborns, with symptoms like hyperammonemia, seizures, and lethargy. Treatment with a low protein diet helps manage hyperammonemia but outcomes can vary. Pyruvate carboxylase deficiency causes severe ketolacticacidosis, coma, and seizures.<br /><br />The document includes additional resources and referrals for genetic clinics, emergency protocols, and more detailed condition information for families.<br /><br />**Publisher:** American College of Medical Genetics and Genomics, updated in February 2022, partly funded through federal grants.

Keywords

ACT sheet

medical geneticists

newborn screening

elevated citrulline

citrullinemia

hyperammonemia

pediatric metabolic specialist

diagnostic evaluation

urea cycle defects

American College of Medical Genetics and Genomics