Electrolyte disorders: general approach

A short introduction to important electrolyte disorders from a renal perspective. 6 mins.

Rob Hunter, Consultant Nephrologist. Part of Renal in the Edinburgh MBChB.

Electrolyte disorders differ from many other medical conditions in two respects.

• Electrolyte disorders are by definition diagnosed by laboratory tests – these are the presenting information. So you must go back and obtain a thorough history and complete a physical examination – these may be critical in arriving at a diagnosis. In particular, a complete drug history is important.
• We can use our understanding of the underlying pathophysiology as a framework when thinking about diagnosis and management. All electrolytes are controlled by homeostatic, negative feedback loops. An electrolyte disorder arises if there is a problem somewhere in this loop or if there has been a massive physiological perturbation sufficient to overwhelm the usual homeostatic mechanisms.

Specific electrolyte disorders

• Potassium disorders; hyperkalaemia, hypokalaemia
• Sodium disorders; hypernatraemia, hyponatraemia
• Calcium disorders (with a kidney bent); hypercalcaemia, hypocalcaemia

Further info

• Open TextBook – Basic but good background info about physiology of key electrolytes, with quiz, from the Anatomy and Physiology open textbook– from Rice University, distributed via the University of British Columbia’s OpenEd project.