Thrombocytopenia is incredibly common in the ICU but can have numerous causes. Diagnostic testing for related conditions such as heparin-induced thrombocytopenia can be expensive and result in inappropriate alterations in care. Using a collaborative approach with engineers at the University of Pittsburgh, we are conducting large scale modeling of databases of critically ill patients to define endotypes of thrombocytopenia and better understand the clinical variables related and how to best identify the source of thrombocytopenia in the critically ill patient.