Regular monitoring of clinical and nutritional status, to determine adequacy of nutrient intake and to guide modifications in the dietary prescription, is central to management of individuals with PROP.  Diet history, activity level, anthropometric, and biochemical data are assessed by the metabolic dietitian at each clinic visit. In a comprehensive diet history, intake from enteral and parenteral sources and supplements is analyzed for nutrient adequacy and evaluated for any variance from the diet prescription. The patient’s eating schedule, home-monitored urinary ketones, and reports of vomiting or poor eating are utilized to detect any early signs of metabolic instability.  Anthropometric assessment compares weight, length/height, and growth velocity for infants and children, and body mass index for older patients to standards. Physical assessment, including feeding skills, is recommended to detect the potential for nutrient insufficiencies. Monitoring developmental milestones and psychomotor skills are included in patient assessment.

Assessment of protein status, including albumin and prealbumin (transthyretin), and blood urea nitrogen, provide information about visceral protein status. Plasma amino acid analysis is used to determine the concentration and balance of essential amino acids, and the adequacy of those limited in the nutrition management of PROP (VAL, ILE, MET, THR). Other biochemical indicators of PROP management  assessed are plasma acylcarnitine profile and plasma carnitine.  Plasma organic acid analysis and blood ammonia concentrations may be tested if signs of metabolic instability or metabolic stressors are present. Monitoring signs of hematologic changes, suggestive of nutritional anemias and hematologic diseases (i.e. thrombocytopenia and pancytopenia) may be is necessary. Routine monitoring includes complete blood count/differential and ferritin. Additional biochemical monitoring that is clinically indicated may include essential fatty acids, vitamins and trace elements and is warranted when physical signs and symptoms are noted.  Assessing bone status indices may be performed in patients who are at risk, including failure-to-thrive and protein malnutrition or long term parenteral nutrition. Secondary complications: pregnancy, transplantation, acute metabolic crises and other circumstances trigger additional monitoring.