Happened often in inpatient setting in sick patients. Should somewhat make you nervous. Medication, infection and immunothrombosis is the three most common cause of thrombocytopenia in inpatient setting. Also variety of conditions (Table 16.1) and medications (Table 16.2) can trigger thrombocytopenia. With a sign of organ damage, it is critical to check PBS to r/o schistocytes. If +, suspect TMA and follow TMA workup in Fig. 16.2. PLASMIC score to differentiate TTP vs HUS by estimating ADAMATS 13 levels. 4T score for risk stratify the potential of HITT (Fig. 16.3 and Table 16.9). There are many diagnostic criteria for DIC, SIC and JSTH score in Tables 16.7 and 16.8.