An inborn error of metabolism presenting with apparently isolated subacute neuropsychiatric symptoms in an adolescent.

We discuss a previously healthy adolescent male presenting with subacute neuropsychiatric issues, tremors, hyperreflexia, and hypertension. Laboratory studies revealed acute on chronic kidney disease. Additional investigations yielded a treatable late-onset inborn error of metabolism (IEM). Late-onset forms of IEMs may present very differently than early-onset disease manifestations (e.g., neuropsychiatric issues may be the predominant symptom), thus leading to the underrecognition of a treatable underlying etiology.