Hyponatremia review [article]

Sally Bissett, Cristina Pérez Vera
Hyponatremia ADH = antidiuretic hormone; Na + = sodium; P osm = plasma osmolality PROFILE Definition Hyponatremia is defined as a plasma sodium (Na + ) concentration < 140 mEq/L in dogs and 150 mEq/L in cats. 1 Because plasma Na + concentration is the main determinant of plasma osmolality (P osm ), hyponatremia usually reflects hypoosmolality. Since the kidneys are highly efficient in excreting water, hypoosmolality almost always implies a defect in renal water excretion and excess of water in
more » ... he body due to one of the following mechanisms: G Impaired diluting ability in the loop of Henle and distal tubule (volume depletion, renal failure, diuretics) G Increased collecting-tubule permeability due to the presence of antidiuretic hormone (ADH) (effective circulating volume depletion, inappropriate ADH secretion, pain, adrenal insufficiency, or hypothyroidism) Consultant on Call / NAVC Clinician's Brief / February 2010 .
doi:10.7892/boris.40592 fatcat:r33lda4qsbd3bh3vucibyn3sly