AKI should be your bread and butter (Fig. 13.1, and Table 13.1). One of the most common things you encounter in inpatient medicine. Yes, our miserable life as a hospitalist is dictated by the value of ‘creatinine’. AKI workup is based on ‘3–3-5’ diagram (Fig. 13.4). There are certain tools you use to delineate which category your patient falls into. New cytotoxic markers which predict the outcome way better than ‘creatinine’ is coming but slow (Fig. 13.2 and Table 13.2). There are certain conditions that you use prediction rules, CIN after PCI (Table 13.5), Rhabdomyolysis (Table 13.6), worsening renal function with HF admission and CKD after AKI (Table 13.8).