Hypotonic Dehydration

Chapter: Hypotonic Dehydration
McMaster Section Editor(s): Christine M. Ribic, Karen C.Y. To
Section Editor(s) in Interna Szczeklika: Franciszek Kokot, Robert Drabczyk
McMaster Author(s): Anna Mathew
Author(s) in Interna Szczeklika: Franciszek Kokot, Edward Franek, Robert Drabczyk
Additional Information

Definition, Etiology, PathogenesisTop

Hypotonic dehydration is loss of water associated with decreased effective osmolality of body fluids.

Causes include loss of isotonic fluids via the kidneys or gastrointestinal tract that has been partially compensated by drinking hypotonic fluids (eg, unsweetened tea). This results in a shift of water from the extracellular fluid (ECF) to the intracellular fluid (ICF), which leads to cellular edema (particularly affecting the central nervous system) and a further reduction of the extracellular compartment (worsening of hypovolemia).

Clinical FeaturesTop

Manifestations are a consequence of hypovolemia and, if present, of cerebral edema. Thirst is usually absent.


Diagnosis is based on the presence of symptoms of dehydration, hypovolemia, hyponatremia, and on decreased serum osmolality.


The management is similar to hyponatremia with hypovolemia. The rate of correction of hyponatremia must be carefully controlled.

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