At a glance:
About: Hyperkalemia the medical term for an increased level of potassium in the cat’s blood.
Causes: It commonly occurs as a result of decreased urinary excretion, which may be due to kidney disease, urinary blockages, ruptured bladder, Addison’s disease and reperfusion injury.
Symptoms: Cardiac arrhythmias, twitching, lethargy, muscle weakness, gastrointestinal disturbances, and depression.
Treatment: Manage the underlying condition as well as fluid therapy to increase urinary output to bring down levels.
Hyperkalemia is the medical term for high levels of potassium in the blood. Potassium is an essential electrolyte (body salt) which performs several functions such as:
- Regulating nerve impulse and muscle contractions.
- Maintains intracellular volume.
- Assists in maintaining blood pressure.
- Maintains heart function.
- Maintains the body’s electrolyte balance and acid/alkali levels in cells and tissues.
- It also plays an important role in heart, skeletal, and smooth muscle contraction, making it an important nutrient for normal heart, digestive, and muscular function.
Hyperkalemia occurs due to decreased potassium excretion via the urine. Normal blood values for potassium are 3.5-5.8 mmol/L
Decreased urinary excretion is the most common cause of hyperkalemia in cats due to kidney failure. It is the role of the kidneys to remove excess potassium from the blood via the urine if they are no longer functioning as efficiently potassium levels can build up.
Acute (sudden onset) or chronic (slow and progressive). Chronic kidney failure is seen more commonly in middle-aged to senior cats. There are a number of causes of acute kidney failure such as ingestion of toxins (such as lily or ethylene glycol).
Shift of potassium from the intracellular fluid into the extracellular fluid
98% of the body’s potassium is found within the cells). Causes of a shift include cell death (lysis) and acid-base abnormalities.
These occur when crystals or stones lodge in the urethra. Urine is unable to pass the blockage, causing it to build up in the bladder. Once this occurs, the kidneys stop functioning/or become less efficient, and again, blood levels of potassium build up. Males are more prone to developing urinary blockages due to their narrower urethra.
Trauma (such as being hit by a car or a fall from a height) or urinary blockage. Fluid leaks into the abdomen, causing a build-up of toxic wastes, including potassium. Obviously, once the bladder is ruptured, urine can no longer be excreted from the body, making the problem worse.
An endocrine disorder due to a deficiency of corticosteroids, which the adrenal glands produce. One hormone, aldosterone, is responsible for regulating water, salt, and potassium levels in the blood.
This condition develops when blood glucose can’t get into the cells for energy due to lack of insulin. The body breaks down fat as an alternate energy sauce, which causes the blood to become too acidic and hyperglycemia (high blood sugar). Acidosis and hyperglycemia can cause potassium to move from the cells and into the blood circulation.
A serious condition which occurs when blood flow is restored after a blockage has occurred (such as blood clot). During blockage (known as ischemia), cells are deprived of oxygen leading to a cascade of biochemical reactions occur leading to toxic build up. Once blood flow is restored, these by-products are released into the circulatory system and hyperkalemia can occur.
Not all cats will show signs of hyperkalemia. When they do occur, it is usually when levels have become dangerously high (above 7 mmol/L). Symptoms of hyperkalemia may include:
- Cardiac arrhythmias
- Muscle weakness
- Gastrointestinal disturbances
In addition to the symptoms listed above, the underlying cause will also produce symptoms.
- Increased urination and drinking
- Anorexia (loss of appetite)
- Bad breath
- Loss of coordination
- Frequent trips to the litter tray, your cat may be seen straining, crying, licking his genitals (males are most often affected due to their narrower urethra)
- A small amount of urine may be produced or none at all if he has become completely blocked
- Blood in the urine
- Abdominal pain
- Abdominal swelling
- Inability to urinate at all
- Abdominal pain
- Abdominal swelling
- Increased thirst and urination
- Fruity smelling breath
- Loss of appetite
- Vomiting and diarrhea
- Weight loss
- Biochemical profile. Elevated BUN and creatinine levels which will be elevated in cats with kidney disease as well as a cat who has a urinary blockage. Hyperglycemia may occur in cats with diabetes or ketoacidosis.
- Complete blood count to evaluate the blood. If red blood cell count is reduced that may point towards chronic kidney failure.
- Urinalysis to look for blood in the urine, urinary crystals, white blood cells and evaluate kidney function.
- ECG to evaluate the heart for arrhythmias.
- Ultrasound or abdominal x-rays to check the bladder and urinary tract for rupture or blockage.
The goal of treatment is to manage the underlying condition as well as fluid therapy to increase urine output and bring down potassium levels. This may include:
- 0.9% sodium chloride (NaCl) to increase urination
- 10% calcium gluconate to help counteract the effects of hyperkalemia on the heart
- Sodium bicarbonate (NaHCO3) to correct acidosis
- Glucose (with or without insulin) to push potassium back into the intracellular fluid
Treating the underlying cause:
- Kidney failure (chronic) – Low protein and phosphate diet along with phosphorous binders, which reduce the absorption of phosphate.
- Kidney failure (acute) – Find and treat the underlying cause, this may include inducing vomiting, gastric lavage or activated charcoal to reduce absorption of ingested toxins, fluid therapy to help the kidneys flush out toxins and supportive care. If the kidneys have completely stopped urine production, peritoneal dialysis or hemodialysis will be necessary.
- Ketoacidosis – Proper management of diabetes.
- Urinary blockage – Removing the blockage, usually by catheterisation. If the blockage can’t be relieved via the methods listed above, an emergency perineal urethrostomy will be necessary. This involves surgery to create a new urethral opening.
- Removal of urine from the bladder or abdomen if the cat is has a blockage or a ruptured bladder.
- Ruptured bladder – Surgery to repair the bladder.
- Addison’s disease – Lifelong administration of the deficient adrenal hormones.
Follow-up appointments with your veterinarian will be necessary to monitor your cat’s heart.
Cats who have had a urinary blockage are at risk of a recurrence. Your veterinarian may recommend a change in diet if your cat is at risk. This may include a switch to wet food (raw or canned) or a prescription diet.