Why Is My Dog's Blood Potassium Level Abnormal ?
Why Is My Cat's Blood Potassium Level Abnormal ?
To see what normal blood and urine values are for your pet, go here
For an explanation of causes of most abnormal blood and urine tests go here
To see how tests are often grouped, go here
Ron Hines DVM PhD
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Your Pet's Blood Potassium Level
K+ In Your Pet’s Blood
Too low = Hypokalemia
Too high = Hyperkalemia
Dissolved potassium (K+, a positive ion or “cation”) is a major component of the cells of your pet’s body. Potassium is also one of your pet’s blood electrolytes. Much less potassium electrolyte is found in its blood than in its cells: but that amount that is is critical for proper nerve, brain and heart function.
The amount of potassium in your dog or cat 's body is controlled by its kidneys, which excrete excess K+ into its urine.
So kidney problems of any kind can lead to abnormal amounts in the blood stream.
Problems that make your pet’s body more acidic (metabolic acidosis) can also shift potassium from the pet’s cells into its blood stream.
Your pet’s blood platelets contain large amounts of potassium. So health problems that cause clotting can also elevate blood potassium levels.
Your pets blood potassium level needs to remain within very strict limits, or many systems will stop functioning correctly. When blood potassium is too low, muscle weakness and impaired (decreased) kidney function can result.
Both abnormally low and abnormally high blood potassium levels interfere with normal heart beat (arrhythmia). When K+ levels are critically high, heart rates become abnormally slow (bradycardia) and can even cease (cardiac arrest).
Reasons Why Your Pet’s Potassium Levels Could Be Low (Hypokalemia) :
Low blood potassium is most commonly seen in pets with failing kidneys (CRF). These are the pets that drink larger than normal amounts of water and produce large amounts of dilute urine. It is one of the most common health problems veterinarians see in older pets.
Potassium levels can also drop when the kidney's urine flow that was obstructed by things such as stones is suddenly relieved. In those cases, the pet’s kidneys produce excessive amounts of urine (diuresis) as its body cleanses itself of the wastes that accumulated in the blood stream during the period of obstructed urine flow.
The same diuretic effect occurs when your pet receives high doses of diuretic medications (eg furosemide).
Hypokalemia (low blood potassium) can also occur in pets experiencing chronic diarrhea and vomiting (with or without stomach and intestinal inflammation or obstruction) or when fluid accumulates in your pet’s abdomen (as can occur with peritonitis, pancreatitis or the pooled fluids [ascites] of heart and liver failure). The drugs used to remove those fluids (eg furosemide diuretic) can lower your pet’s blood potassium levels as well (“potassium wasting” effect).
Some cats are prone to muscle disease (myopathy) and a few special cats muscle inflammation (eg hypokalemia in Burmese cats, and myopathy in Sphynx cats). Those problem are often accompanied by low blood potassium levels.
A lack of dietary potassium when your pet will not eat could conceivably cause hypokalemia - but in reality it rarely does.
Blood potassium levels go down a bit as the body becomes less acidic (metabolic alkalosis, high blood pH). That can occur due to persistent vomiting or after a period of rapid respiration (panting).
Uncontrolled diabetes, Insulin injection overdose, adrenaline release due to stress, bacterial endotoxemias and high doses of corticosteroid medications have all been associated with hypokalemia.
Pets given large amounts of IV fluid in emergency situations when no potassium was added to the fluids or when it contained large amounts of bicarbonate buffer, can cause a pet's blood potassium level to drop.
Fatty blood specimens (lipemic serum) will give incorrectly low potassium reading on some blood analyzer machines (pseudohypokalemia).
Reasons Why Your Pet’s Potassium Levels Could Be High (Hyperkalemia) :
Dogs and cats with acute (sudden) onset of kidney disease that includes kidney swelling and shut down (oliguric renal failure) no longer have the ability to produce sufficient urine (anuric kidney disease) to remove excess potassium from their bodies. In those cases, hyperkalemia usually develops.
Antifreeze poisoning, antibiotics like gentamycin and amikacin (aminoglycosides) trimethoprim, digoxin, ACE inhibitors like enalapril given for heart problems and leptospirosis infection can all be responsible for higher than normal blood potassium levels.
The same situation occurs when urinary tract stones when the pet's kidneys are prevented from flushing excess potassium out of the pet's blood stream. Feline urological syndrome (FUS), or other problems that interfere with the normal flow of urine will have the same effect. So will any tears in the bladder, or ureters which leak urine into the pet’s abdomen.
Pets (usually dogs) whose adrenal glands no longer produce sufficient aldosterone hormone (as in Addison’s disease, perhaps whipworm infection = pseudoaddisons) often have higher than normal blood potassium levels.
Many chronic health problems lead to a body that is too acidic (metabolic acidosis). All of them can raise your pet’s blood potassium levels. They include uncontrolled diabetes (diabetic ketoacidosis), starvation, shock and all the things that cause low blood pH, low blood bicarbonate or C02 levels and high anion gap.
High potassium reading can be false (an artifact) when they are run on blood samples that had partially clotted hemolized or sat too long.
Akitas, and perhaps other Japanese breeds of dogs, have naturally high levels of potassium in there red blood cells that make their blood readings hard to interpret (pseudohyperkalemia).
Not centrifuging the blood and separating off the serum for analysis soon enough will always make the potassium reading a bit higher. Elevated WBC counts and elevated reticulocyte counts can raise blood potassium levels as well.
Because most of your pet’s potassium resides in the cells of its tissue, not in its blood, just about any crises that causes sudden tissue destruction can cause a sudden increase in blood potassium levels too. Those can be traumatic, infectious, cancerous or obstructions to circulation.
Complementary Tests :
Because changes in potassium have so many causes, tests are too numerous to list. But your veterinarian might begin with: CBC/WBC and blood chemistry values, urinalysis, sodium:potassium ratio , ACTH stimulation test if Addison’s disease is suspected, electrocardiogram (ECG)