Blood biochemistry: potassium

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Sections available in full article Overview, Uses, Sampling, Source of test material, Quantity of test material, Sample collection technique, Quality control, Test (s), Methodologies, Availability, Technique (intrinsic) limitations, Result data, Normal (reference) values, Abnormal values, Errors and Artifacts, Sources, Publications, Vetstream contributor(s),
Contributors Dr Kathleen P Freeman DVM MS PhD MRCVS
Synonyms K

Overview

  • 98% of potassium is intracellular but passive and freely diffusable in and out of cells.
  • Distribution across cell membrane crucial in cardiac and neuromuscular membrane potentials.
  • Major intracellular cation.
  • Intracellular location maintained by ATP - dependent sodium:potassium pump.
  • Changes in plasma levels reflect fluid balance, rate of renal excretion and changes in balance between intra- and extracellular fluid.

Uses

In combination

  • As part of routine biochemical screening panel.
  • Measured in conjunction with other electrolytes, eg sodium Blood biochemistry: sodium , chloride Blood biochemistry: chloride , and bicarbonate where metabolic disturbances may be suspected, eg severe vomiting and diarrhea.
  • Hyperkalemia Hyperkalemia may be found in renal disease.
  • Hypokalemia often due to excess renal or gastrointestinal loss.
  • In combination with urine elecrolyte concentrations for fractional electrolyte excretion Fractional electrolyte excretion in assessment of renal failure or other conditions.

Result data

Normal (reference) values

  • 3.6-5.8 mmol/l (mEq/l).
    Serum>plasma as potassium released from platelets during clotting.

Abnormal values



Hyperkalemia Hyperkalemia
  • Increased body potassium content:
    • Hypoadrenocorticism Hypoadrenocorticism.
    • Normal body K-content (redistribution).
    • Post-renal obstruction.
    • Distal renal tubular acidosis.
    • Hypoaldosteronism.
    • Prolonged spironolactone therapy Spironolactone.
    • Low sodium diet Dietetic diet: for cardiac insufficiency.
    • Acute renal failure Kidney: acute renal failure.
    • Bladder rupture Bladder: trauma rupture.
    • IV postassium salts, eg potassium benzyl penicillin.
    • Hypovolemia.
  • Normal body potassium content (redistribution):
    • Metabolic acidosis Acid base imbalance.
    • Hyperkalemic periodic paralysis (Pit Bull).
    • Leukemia Leukemia.
    • Diabetic ketoacidosis Diabetic ketoacidosis.
    • Extensive tissue damage (especially muscle).
    • Drug therapy, eg digoxin Digoxin , propanolol Propranolol , ACE inhibitors, potassium-sparing diuretics.


    Hypokalemia
  • Low body potassium content:
    • Chronic vomiting Vomiting or diarrhea Diarrhea: chronic.
    • Post-obstructive diuresis.
    • Renal tubular acidosis.
    • GI fluid loss (if K-rich).
    • Drug therapy, eg loop diuretics, amphotericin B.
    • Hyperadrenocorticism.
    • Diuretic therapy, especially potassium-losing diuretics.
    • Chronic liver disease Liver: chronic disease - overview.
    • Fluid therapy deficient in potassium.
    • Acute renal failure Kidney: acute renal failure (polyuric phase).
    • Burns.
    • Recovery from severe trauma.
  • Normal body potassium content (redistribution):
    • Insulin therapy Insulin.
    • Metabolic/respiratory alkalosis.
    • Aldosterone release.
    • Catecholamine release.
    • Fanconi's syndrome Fanconis syndrome.
    • Prolonged anorexia.

Errors and Artifacts



False increase
  • Sample aging due to release from platelets.
  • KEDTA or K-heparin contamination of sample.
  • Hemolysis in Japanese Akita Japanese Akita.
  • Most breeds (apart from Japanese Akita Japanese Akita ) have low concentration of K within erythrocytes so hemolysis does not result in elevation.
    Often show spectacular elevation of [potassium] if sample not analyzed immediately.
False decrease
  • Extreme hyperproteinemia.
  • Lipemia.

Sources

Publications

Other sources of information

  • Ettinger S J & Feldman E C (eds) (2000) Textbook of Veterinary Internal Medicine. 5th edn. Philadelphia: W B Saunders & Co.
  • Kaneko J J, Harvey J W & Brass M L (eds) (1997) Clinical Biochemistry of Domestic Animals. 5th edn. Boston: Academic Press.
  • Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine. Clinical Pathology. 3rd edn. Iowa: Iowa University Press.

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