Presentations to the emergency department with a diagnosis of hypocalcaemia-induced tetany secondary to total thyroidectomy are rare. A patient presented to the emergency department of a regional Australian hospital with hypocalcaemia-induced tetany. A case study was employed to reflect on the care provided and identify knowledge practice deficits within this unusual patient presentation. Calcium plays a central role within the nervous system and is vital for both cardiac and muscular contraction. The clinical manifestations of electrolyte disturbances such as hypocalcaemia can be life threatening, and therefore, appropriate assessment, monitoring and management are essential to ensure positive patient outcomes. Understanding the importance of calcium imbalance for the emergency and critical care nurse is paramount in preventing complications associated with cardiac conduction and muscle tone, especially the potential for airway compromise. Education is central to this and may include clinical case reviews, the application of pathophysiological presentations of electrolyte imbalance and a review of electrolyte administration guidelines. Understanding the role of calcium within the body will assist emergency and critical care nurses to assess, monitor and intervene appropriately, thereby preventing the life-threatening manifestations of hypocalcaemia.