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Principal Reasons for Performing the Test
High potassium (hyperkalemia) is usually found in urinary obstruction, renal failure, metabolic or
respiratory acidosis, and hypoadrenocorticism as well as excessive hemolysis for horses, cattle,
cats, and some breeds of dogs. Decreased values (hypokalemia) usually follow excessive salt loss
through severe vomiting or diarrhea, inadequate intake, anorexia (especially cats), malabsorption,
and severe burns.
Most Common Abnormalities Indicated by the Test
Hyperkalemia—renal failure, postrenal obstruction.
Hypokalemia—excessive loss of potassium.
Sample Type and Precautions
Remove plasma or serum promptly from cells or clot. If plasma is being collected, use only lithium
heparinized samples. Avoid hemolysis.
Do not freeze samples for use with the Catalyst One analyzer.
Complementary Tests
Sodium, potassium, and chloride should always be assayed together to determine electrolyte
balance. The additional measurement of bicarbonate will allow accurate assessment of metabolic
acid-base physiology.
ACTH stimulation test for suspect cases of hypoadrenocorticism.
Reaction Sequence
Sodium (Na)
Sodium is the major cation of extracellular fluid, where it maintains osmotic pressure, acid-base
balance, and transmits nerve impulses. The body maintains total sodium content, and only slight
changes are found even under pathologic conditions.
Principal Reasons for Performing the Test
To evaluate electrolyte status in conjunction with potassium and chloride levels.
Low sodium (hyponatremia) is usually caused by a relative excess of body water. Reduced levels
may be due to low intake, loss through vomiting or diarrhea plus adequate water and inadequate
salt replacement, salt-losing nephropathy, osmotic diuresis, metabolic acidosis, and various
glandular conditions.
Elevated values (hypernatremia) usually follow water loss in excess of salt loss through profuse
sweating, severe vomiting or diarrhea, inadequate water intake, and dehydration of renal sodium
conservation in hyperaldosteronism.
Most Common Abnormality Indicated by the Test
Hypernatremia secondary to dehydration, gastrointestinal fluid loss (vomiting or diarrhea).
Sample Type and Precautions
Remove plasma or serum promptly from cells or clot. If plasma is collected, use only lithium
heparinized samples. Avoid hemolysis.
Do not freeze samples for use with the Catalyst One analyzer.
Appendices
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