Page 165 - Basic Monitoring in Canine and Feline Emergency Patients

(A) Water loss (without concurrent Na loss)
Diuresis
hypotonic fluid loss Renal - Osmotic (e.g.
VetBooks.ir • GI tract (vomiting, diarrhea) - Drug-induced (e.g.
failure
hyperglycemia)
• Cutaneous surfaces
• Third space fluid loss
furosemide)
Na level in Water loss via the
blood kidney (without Lack of
concurrent Na loss) antidiuretic
hypotonic fluid hormone
loss effects (e.g.
diabetes insipidus)
Exogenous
salt gain Renal
reabsorption Na Angiotensin

Decrease
in GFR
Catecholamines Aldosterone

(B) Renal Na level in Increased water
reabsorption Na blood intake

Liver
Water gain failure
Atrial
Increase natriuretic (without
in GFR concurrent Na
peptide gain) Congestive
heart
failure
Water AND Na loss
hypertonic fluid loss
• GI tract (vomiting,
diarrhea) Antidiuretic
• Cutaneous surfaces hormone Oliguric or
Renal loss Na + water • Third space fluids anuric renal
(e.g. Diuretics, failure
hypoadrenocorticism)

Fig. 8.1. The basic mechanisms for the development of hypernatremia and hyponatremia. (A) Hypernatremia is
a result of either a gain of sodium (ingestion of salt without water, infusion of hypertonic fluids with a high sodium
content), a loss of free water in excess of sodium loss (hypotonic fluid or pure water losses), or retaining sodium in
excess of water at the level of the kidney. (B) Conversely, hyponatremia results from losing sodium in excess of water,
gaining pure water that dilutes blood sodium, or retaining less sodium at the level of the kidney. GFR, glomerular
filtration rate; GI, gastrointestinal; Na, sodium.

occur very rapidly can also result in clinical signs. signs can include changes in behavior/mentation,
Clinical signs are most commonly neurologic since ataxia, and seizures or seizure-like events. In some
the effects of changes in blood osmolality are most cases (especially in more chronic conditions), clini-
evident in cells of the nervous system. Neurologic cal signs can be non-specific such as anorexia or

Electrolyte Monitoring 157