Numerous barriers, listed below, interfere with the provision of optimal care for individuals with PKU. While infrastructure, patient-related, and regulatory barriers present significant challenges, implementation of recommendations in this guideline has minimal impact on resource needs. The recommendations clarify management goals and support clinical decision-making without adding to the number of clinic visits or testing, or the amount of contact time with the metabolic dietitian.

Infrastructure barriers to implementation include:

• Limited number of trained metabolic geneticists and dietitians
• Limited number of appropriate and accessible clinics, hospitals and laboratories to treat and monitor patients

Patient-related barriers to implementation include:

• Limited understanding of the disorder, treatment, and monitoring
• Limited financial resources for covering cost of treatment (medical foods, modified low protein foods, sapropterin and pegvaliase therapy)
• Limited financial resources for covering other PKU-related medical costs (clinic visits, laboratory testing, transportation)
• Language barriers
• Low literacy or compromised cognition and psychosocial abilities resulting from poor metabolic control 

Regulatory barriers to implementation include:

• Lack of uniform federal regulations that mandate third party coverage for medical foods, modified low protein foods, monitoring supplies, adjunct and alternate therapies, and metabolic dietitians' services for all individuals with PKU, regardless of age
• Limited federal funding for outcome studies of rare inborn metabolic disorders, and limited time that metabolic specialists (both MDs and RDs) are able to devote to in-depth research because of their extensive clinical responsibilities