This new online Clinics series, Hospital Medicine Clinics, provides evidence-based answers to clinical questions the practicing hospitalist faces daily. This third issue in our growing online database covers essential updates in the following topics: B-type natriuretic peptide; procalcitonin; erythrocyte sedimentation rate and C-reactive protein; urine lytes; rational testing in patients with gastrointestinal bleeding; antinuclear antibody testing; serum protein electrophoresis, urine protein electrophoresis, and immunoelectrophoresis; patient-controlled analgesia; total parenteral nutrition and peripheral parenteral nutrition; and rational lab testing.