Bedside evaluation of a patient’s intravascular volume status is challenging, even for the seasoned practitioner. There is no single diagnostic test to determine whether a patient is hypovolemic, hypervolemic, or euvolemic. Often, underlying or concomitant disease states, medications, and other therapeutics can make available data difficult to interpret. Therefore, a combination of clinical evaluation, laboratory studies, and other diagnostics are required to make a clinical judgment regarding volume status. Patients who demonstrate alterations in their volume status are likely to have electrolyte abnormalities as well, and assessment of serum electrolyte values and potential therapeutic interventions is a vital piece in caring for critically ill patients.