In this inquiry-based lab, students are provided with a case study involving a young boy with a head injury exhibiting various symptoms, as well as simulated blood and urine samples to help diagnose the boy's disease. Throughout the course of the lab, students research, design, and conduct a series of tests culminating in a patient prognosis. All of the materials, which simulate the blood, urine, and testing compounds, are readily available at the grocery store or online. This real-world problem engages the students to think about negative feedback systems, patient symptoms, the hormones associated with blood glucose levels and urine production, as well as the detection techniques employed by physicians to diagnose patients. Diagnostic methods, testing procedures, and the disease itself make this lab extraordinarily relevant to the lives of students, as evidenced by our students' reactions to the lab.