Disorders of Sodium and Water Homeostasis

The answer first

Disorders of sodium and water homeostasis turn a deranged serum sodium into a decisive bedside pathway: confirm true hyponatraemia or hypernatraemia, judge the time-course and symptom severity, classify the tonicity and volume status, and commit to a therapy whose rate of correction is as important as the agent chosen.^[1]

The single most dangerous error is treating a number rather than a mechanism — administering hypotonic fluids to a hypervolaemic patient, or aggressive isotonic saline to a euvolaemic SIADH patient. The 8 to 10 mmol/L per 24 hours correction limit in chronic hyponatraemia is the cardinal safety endpoint, because exceeding it causes osmotic demyelination.^[1][6]

References12ShowHide

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