Chronic disease management involves frequent administration of invasive lab procedures in order for clinicians to determine the best course of treatment regimes for these patients. However, patients are often put off by these invasive lab procedures and do not follow the appointment schedules. This has resulted in poor management of their chronic conditions leading to unnecessary disease complications. An AI system that is able to personalize the prediction of individual patient lab test responses will enable clinicians to titrate the medications to achieve the desired therapeutic outcome. Accurate prediction of lab test response is a challenge because these patients typically have co-morbidities and their treatments might influence the target lab test response. To address this, we model the complex interactions among different medications, diseases, lab test response, and fine-grained dosage information to learn a strong patient representation. Together with information from similar patients and external knowledge such as drug-lab interactions and diagnosis-lab interaction, we design a system called KALP to perform personalized prediction of patients’ response for a target lab result and identify the top influencing factors for the prediction. Experiment results on real-world datasets demonstrate the effectiveness of KALP in reducing prediction errors by a significant margin. Case studies show that the identified factors are consistent with clinicians’ understanding.