Comprehensive Nutrition Assessment:

1. Conduct regular nutrition evaluations to assess adequacy of and adherence to the nutrition prescription, including dietary history and usual intake patterns, nutrient analysis, evaluation of feeding skills, growth, physical activity level, laboratory results, and nutrition-related physical findings. See TABLE #2, Monitoring the Nutritional Management of an Individual with UCD when Well for frequency. 

2. Correlate nutrient intake data obtained from nutrient analysis with plasma amino acid profiles and other relevant biochemical markers to evaluate the effectiveness of the nutrition prescription and inform necessary adjustments. 

3. If able to obtain labs and anthropometrics when needed, it is appropriate to use telemedicine for routine clinic visits in individuals with mild or severe UCD. 

Age-Specific Anthropometric Monitoring

1. Monitor age-appropriate anthropometrics (e.g., weight, length/height, BMI, and head circumference). See TABLE #2, Monitoring the Nutritional Management of an Individual with UCD when Well for frequency.

2. Evaluate growth patterns longitudinally to identify trends, including risk for poor linear growth or rapid and/or excessive weight gain.

Biochemical Monitoring When Clinically Well

1. Monitor relevant biochemical markers (e.g., plasma amino acids profile, ammonia, comprehensive metabolic panel, complete blood count, 25-OH vitamin D) to assess metabolic control, nutritional adequacy, and response to dietary intervention. See TABLE #2, Monitoring the Nutritional Management of an Individual with UCD when Well.

2. Draw blood for plasma amino acids 3-4 hours after a meal and at a consistent time of day, ideally at least one week after dietary changes, to allow for accurate interpretation in relation to intake, supplementation, and clinical status. 

3. Use plasma glutamine as an indicator of metabolic control, targeting glutamine concentrations below 1000 µmol/L to reduce risk of neurotoxicity and support metabolic stability. 

4. In individuals with ARG, target plasma arginine concentrations below 200 µmol/L to reduce risk of neurological complications. 

5. Maintain plasma arginine within the normal range for most UCDs to support nitrogen excretion and metabolic stability. 

6. Monitor plasma amino acids (including BCAA, EAA, arginine, and citrulline) as the primary biochemical measure to assess protein adequacy in UCDs. 

7. Maintain essential amino acids and branched chain amino acids within normal reference ranges to prevent protein catabolism. 

8. Consider additional biochemical markers and/or more frequent monitoring when clinically indicated (e.g., signs and symptoms of nutritional inadequacy, long-term poor adherence, intercurrent illness, acute metabolic decompensation (see question 1), and pregnancy (see question 7). See TABLE #2, Monitoring the Nutritional Management of an Individual with UCD when Well.

Bone Mineral Density

1. Consider, in consultation with providers, periodic bone mineral density assessment in individuals on a protein-restricted diet to establish baseline status and monitor trends over time, allowing for early detection of declining bone density and proactive intervention to prevent osteopenia and osteoporosis.

Assess Developmental, Psychomotor, and Neurocognitive Status

1. Include age-specific neurodevelopmental and cognitive assessments as part of multidisciplinary, comprehensive care for all individuals with UCD, regardless of severity.

2. Include patient- and caregiver-reported health-related quality of life measures as part of routine care to evaluate the burden of disease and treatment, and refer for support services as needed.