Graduation Year


Document Type




Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department


Major Professor

Kathy Bradley-Klug, Ph.D.

Committee Member

Jennifer Wolgemuth, Ph.D.

Committee Member

Amarilis Sanchez, M.D.

Committee Member

Shannon Suldo, Ph.D.

Committee Member

Kathleen Armstrong, Ph.D.


interviews, metabolic disorders, pediatric psychology


Phenylketonuria (PKU) is a rare inborn error of metabolism that can be managed through lifelong treatment adherence to a restricted diet and supplemental medical formula (Vockley et al., 2014). Untreated PKU can result in severe intellectual disability, anxiety, depression, executive functioning deficits, and seizures (Cappelletti et al., 2013; Moyle et al., 2007). Even individuals who are continuously treated for PKU can experience high rates of anxiety and depression, executive functioning deficits, social difficulties, and lower full-scale IQ scores than their siblings and parents (Bosch et al., 2015; Manti et al., 2016; Waisbren et al., 2007). Additionally, adolescents are at risk for social difficulties due to the restricted diet and treatment of PKU (Bosch et al., 2015). Quality of life is just beginning to be studied in individuals with PKU. Most studies have focused on adults or on parent or clinician ratings of children and adolescents’ quality of life. Results of these studies have been varied with some individuals with PKU and their parents reporting normal quality of life compared to peers (Cazzorla et al., 2014; Thimm, Schmidt, Heldt, & Spiekerkoetter, 2013) and others showing parents rate their children with PKU as being less happy, confident, and joyful than healthy peers (Landolt, Nuoffer, Steinmann, & Superti-Furga, 2002).

A qualitative interview study was conducted with five adolescents with PKU between the ages of 14 and 18 years. The purpose of this study was to gain an in-depth awareness of the beliefs and perceptions of these adolescents with PKU on how they understand and conceptualize their condition, the impact it has on their life, factors that influence their quality of life, and perceptions of their peer relationships in regard to their illness. A romantic conceptualization of interviewing was used to build rapport and trust between the interviewer and interviewee in order to access the authentic self of each participant (Roulston, 2010a). Each adolescent participated in a series of four semi-structured individual interviews. Data were analyzed using thematic analysis (Braun & Clarke, 2006).

Results indicated adolescents with PKU describe their overall quality of life in positive terms and report similar influences on their life satisfaction and quality of life as other adolescents. Adolescents with PKU identified relationships with family and friends as the most salient influence on their life satisfaction. They largely perceive their social lives to be similar to their peers and believe they are more similar to their peers than different. Adolescents with PKU describe few challenges in social settings and view these challenges as simply inconveniences. However, adolescents with PKU minimize their condition and the impact it has on their life. When talking about PKU, sharing it with others, or when it comes up in social situations they use words that describe it as minor in consequence and significance. The majority of participants had a general understanding and knowledge of how they got PKU, their treatment, and potential consequences. Nevertheless, adolescents also reported a number of incorrect consequences, a lack of awareness of consequences, and misconceptions about PKU and the impact it can have on their life. Implications for medical providers and behavioral health professionals who work with adolescents with PKU include the importance of monitoring and providing extra support during natural transition times, such as moving from elementary school to middle school and then to high school. Current findings also indicate there is room for improvement in health literacy among adolescents with PKU and specific strategies are discussed. Future research should continue to explore the experiences of individuals with PKU during late childhood and early adolescence, the time frame identified as most difficult in the current study. Another direction for future research is further exploration of how PKU influences the idea of self-concept and self-image.

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