From Dog

Hyponatremia is defined as a blood sodium level <135 mEq/L (normal is 140 - 165).

Body stores of sodium and potassium are intimately related and maintained by balanced intake and excretion, intracellular and extracellular osmotic pressure, and pH[1]. Hyonatremia is commonly associated with hyperkalemia[2].

Sodium-potassium (Na:K) ratio has frequently been used as a diagnostic tool to identify adrenal insufficiency.

The normal Na:K ratios in dogs range from 27:1 to 40:1, while the values in canine hypoadrenocorticism (Addison’s disease) are often below 27:1 and may be below 20:1 in primary hypoadrenocorticism, characterized by hyponatremia, hypochloremia and hyperkalemia[3].

Other disorders which can cause hyponatremia include:

Clinically affected dogs present with dehydration, lethargy, myalgia, cramping and reluctance to walk.

Parenteral electrolyte replacements are usually sufficient to correct hyponatremia.


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  3. Feldman, EC & Nelson, RW (1996) Canine and feline endocrinology and reproduction. pp:266-281, 2nd ed. WB Saunders, Philadelphia, 1996
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