Electrolyte disorders in the critically ill

Electrolyte disturbance is almost ubiquitous in the critically ill. Competent analysis and management are crucial in providing quality intensive care, as evaluation may provide an aid to the diagnosis, a marker of disease severity and recovery, while specific electrolyte derangement may require specific management. While many electrolyte abnormalities can be managed by simply increasing intake to reverse deficits and reducing intake and encouraging loss for excess levels, generalizing this approach is over-simplistic. Disturbed serum levels do not always reflect the total body stores of the electrolyte but may reflect a pathological process that requires specific definitive treatment. While established recipes for electrolyte replacement to correct abnormalities serve as a starting point, these cannot replace repeated clinical examination, and sequential measurement of the electrolytes. In this paper we provide a review of and a guide to the aetiology, analysis and management of the major electrolytes in the critically ill.