Is it necessary to routinely measure levels of blood phenylalanine in adults with a history of phenylketonuria (PKU)? I have a patient who is noncompliant with his supplements (protein replacement) and is resistant to other dietary measures.—CHRISTINE HOWARD, RPA-C, Rochester, NY

In the past, persons with PKU were told to stop the dietary restrictions once past childhood. It was thought that the deleterious effects of high phenylalanine levels were a problem only to the developing brain. As more young adults survived and stopped the dietary restrictions, many began to develop subtle cognitive deficits, including lack of concentration and memory and attention deficits. Therefore, it is recommended that patients stay on the restricted diet, which includes protein supplements as well as dietary restrictions. Regular monitoring of blood phenylalanine levels is recommended; frequency depends on the patient status. Monitoring can be done at a clinic or through mail-based samples. Objective evidence of rising phenylalanine levels along with education regarding the consequences of high levels may help convince a patient to adhere to the restrictions. A wealth of information is available through the NIH MedLine Plus Web site (, accessed May 18, 2010). The Cristine M. Trahms Program for Phenylketonuria at the University of Washington (, accessed May 18, 2010) also offers excellent resources for clinicians as well as educational materials for patients and families.—Claire Babcock O’Connell, MPH, PA-C (140-7)

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