Routine laboratory tests are the most frequently performed among clinical laboratory tests, and they can provide important information for the diagnosis and treatment of patients. They are more useful when sev- eral data are combined to interpret the pathophysiological state of a patient. Changes of routine laboratory data are important even when they are within their reference ranges, and they sometimes show a more de- tailed condition of the patient. In this RCPC, we-focused on changes of albumin and electrolytes, bacterial infections, and anemia. [Review].