Electrolyte Imbalances in Cats

What are electrolyte imbalances in cats?

Electrolyte imbalances occur when levels of electrolytes are too high or too low which can cause significant derangements. Electrolytes are salts that dissolve into positive and negative charges (ions) and conduct electricity when in water. Cations  are positively charged ions and anions are negatively charged ions.

Cats receive electrolytes via the food, which are then absorbed by the intestines and are stored in different parts of the body (bones, soft tissue) as well as two fluid compartments; intracellular fluid (ICF) and extracellular fluid (ECF).

  • Intracellular fluid is the liquid found inside cells
  • Extracellular fluid (ECF) is all body fluid outside of cells and consists of plasma, interstitial, and transcellular fluid

There are seven key electrolytes; sodium, potassium, magnesium, calcium, phosphate, chloride and bicarbonate which control a number of important physiologic functions. An even balance of electrolytes must be maintained, otherwise vital body systems can be affected.

Sodium (Na)

Normal range: 147 – 156 mEq/l

Most of the cat’s sodium is located in the blood and the fluid around cells. Sodium is a positive ion (cation), and combined with chloride which is a negative anion, forms sodium chloride.

  • Maintains fluid volume and balance in and around cells (osmosis)
  • Maintains muscle and nerve function

Hypernatremia (high sodium levels):

Often a complication of critically ill cats whose water intake is inadequate or due to fluid loss from vomiting and diarrhea. Excess ingestion of salt can also cause hypernatremia. High blood sodium levels cause a shift of water out of the cells and can lead to fluid building up around the brain.


  • Increased thirst
  • Confusion and disorientation
  • Vomiting
  • Diarrhea
  • Low body temperature
  • Slow capillary refill time
  • Seizures
  • Coma

Hyponatremia (low sodium levels):

This can be caused by water retention or fluid loss, such as vomiting, diarrhea, Addison’s disease and kidney failure due to an inability of the kidneys to remove extra fluid from the body.


  • Lethargy
  • Weakness
  • Confusion
  • Nausea
  • Vomiting

Potassium (K)

Normal range: 4.0 – 4.5 mEq/l

Potassium is a cation (positive ion), and over 90% is located within the body’s cells (intracellular); the remainder is present in the extracellular fluid of the blood. The kidneys remove excess potassium out of the body via the urine.

  • Regulates nerve conduction as well as skeletal and smooth muscle contractions
  • Maintains intracellular volume
  • Regulates the heartbeat
  • Assists in maintaining blood pressure and intracellular volume

Hyperkalemia (high potassium levels):

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. The most common cause of hyperkalemia is decreased urinary excretion due to kidney failure, urinary tract blockages, ruptured bladder, Addison’s disease and diabetic ketoacidosis which causes potassium to move from the cells and into the blood circulation.


  • Cardiac arrhythmias
  • Twitching
  • Lethargy
  • Muscle weakness
  • Gastrointestinal disturbances
  • Depression

Hypokalemia (low potassium levels):

Can be caused by inadequate consumption of potassium, increased excretion of potassium or shift of potassium from the extracellular fluid into the intracellular fluid.

The most common cause is increased excretion of potassium due to hypomagnesemia (a decrease in intracellular magnesium, caused by magnesium deficiency, releases the magnesium-mediated inhibition of ROMK channels and increases potassium secretion), vomiting or cats with chronic kidney disease or diabetes. Decreased intake can occur in cats with chronic anorexia (loss of appetite). Administration of sodium bicarbonate, insulin and glucose can push potassium from the extracellular fluid into the intracellular fluid.


  • Lethargy (decrease in activity)
  • Weakness
  • Muscle pain (myalgia)
  • Stiffened posture and gait
  • Reluctance to move
  • Ventral neck flexion (inability to raise the head due to muscle weakness)
  • Increased thirst and urination (due to decreased kidney function)
  • Weight loss
  • Muscle wasting
  • Dull coat

Magnesium (Mg)

Normal range: 1.9-2.8 mg/dL

Magnesium is a cation (positively charged ion), 60% of the magnesium in the body is found in bone, while the rest is in muscles, soft tissues (39%), only 1% is located in the extracellular fluid. It is the second most abundant intracellular cation (ion) after potassium. It is involved in 300 enzyme reactions in the body, which include:

  • Maintains normal nerve and muscle function
  • Maintains a steady heartbeat, when calcium enters the cells of the heart muscle, it stimulates the muscle fibres to contract, magnesium counters this effect, helping these cells relax
  • Aids bone growth
  • Regulates blood glucose levels and blood pressure
  • Synthesis of fat, proteins, nucleic acids and coenzymes
  • Magnesium is required for the production and release of parathyroid hormone
  • Adenose triphosphate (ATP) is the primary source of energy in the cells and must bind to a magnesium ion to be biologically active

Hypermagnesemia (high magnesium levels):

This condition is rare in cats and is most commonly associated with kidney failure when the kidneys lose their ability to excrete excess magnesium from the body.


  • Nausea
  • Vomiting
  • Weakness
  • Decreased heart rate
  • Mental depression
  • Paralysis
  • Slow reflexes
  • Reduced respiration
  • Low blood pressure
  • Coma

Hypomagnesemia (low magnesium levels):

The most common causes of hypomagnesemia include malnutrition, poor quality diet, increased renal (kidney) excretion due to kidney disease, hyperthyroidism, diabetes and diuretics.

  • Poor growth of kittens
  • Irritability
  • Anorexia
  • Calcium deposition in soft tissues
  • Convulsions

Calcium (Ca)

Normal range: 7.5 – 10.8 mg/dl

Calcium is a cation (positively charged ion) and the most abundant mineral in the body. It is responsible for many essential functions. 99% of calcium is stored in the bones, the remaining 1% is in the blood, and it is responsible for:

  • Cardiac function
  • Muscle contractions
  • Nerve impulses
  • Blood clotting
  • Stabilises the permeability of the cell membrane to sodium
  • Cell growth
  • Provides strength to the teeth and bones

Several key players including the parathyroid gland, vitamin D, calcitonin (a hormone), the kidneys and the bones (which store excess calcium) are responsible for maintaining calcium levels, and any problem with any of these can cause calcium levels to be too high or low.

Hypocalcemia (low calcium):

Hypoparathyroidism, milk fever, chronic kidney failure, hypoalbuminemia, phosphate enemas, vitamin D deficiency and antifreeze poisoning, acute pancreatitis and diet.


Hypercalcemia (high calcium):

The most common cause of hypercalcemia is idiopathic (IHC), which means no cause can be found. Most cases of hypercalcemia are due to increased gastrointestinal uptake from the food or excessive mobilisation of stored calcium from the bones. Other causes include cancer, primary hyperparathyroidism, Addison’s disease, ingestion of certain houseplants or rodenticides and vitamin A toxicosis.


  • Loss of appetite
  • Increased thirst and urination
  • Weight loss
  • Weakness
  • Neuromuscular disorders
  • Gastrointestinal disturbances
  • Twitching
  • Seizures
  • Mineralisation of the tissues, especially the heart and kidneys

Phosphate (PO4)

Normal range: 3.3 – 7.5 mg/dl

Phosphate is an anion (negatively charged ion) that combines with calcium to form the hard structure of the bones and teeth. 85% of phosphate is stored in the bones and the remainder is located within the intracellular and extracellular compartments. The concentrations of calcium and phosphate are similar and kept in check by several mechanisms including the parathyroid gland, vitamin D, kidneys and the hormone calcitonin. The kidneys remove excess phosphate from the body via the urine and to a lesser degree, the feces.

  • Binds to calcium to build and repair bones and teeth
  • Phosphate is a building block for several important substances, including those used by the cell for energy, cell membranes, and DNA (deoxyribonucleic acid)
  • Plays a role in the regulation of protein, fat and carbohydrate metabolism
  • Helps nerve function
  • Involved in the activation of vitamin D and calcium homeostasis

Hypophosphatemia (low phosphate):

This condition is rare in cats and can occur when extracellular phosphate is redistributed into the intracellular fluid


  • Lethargy
  • Irritability
  • Stiff joints
  • Weakness

Hyperphosphatemia (high phosphate):

The most common cause of hyperphosphatemia is kidney disease due to the reduced ability of kidneys to get rid of excess phosphate. Phosphate enemas can also lead to increased blood levels. When levels increase, phosphate binds to calcium, causing levels to drop.


Chloride (Cl)

Normal range: 111 – 125 mEq/l

Chloride is an anion (negatively charged ion) that is usually consumed as salt, paired with sodium and is the most abundant anion in the extracellular fluid.

  • Chloride works closely with sodium and potassium and helps to keep fluid levels in the body balanced.
  • Maintains blood volume, blood pressure and pH
  • Production of gastric hydrochloric acid

Hypochloremia (low chloride levels):

The most common cause of hypochloremia is prolonged vomiting and diarrhea.


  • Dehydration
  • Tachycardia (increased heart rate)
  • Lethargy

Hyperchloremia (high chloride levels):

Hyperchloremia can be caused by loss of body fluids, such as prolonged vomiting and diarrhea, high levels of blood sodium, kidney failure, and certain drugs (corticosteroids and diuretics).


  • High blood pressure
  • Muscle weakness
  • Irregular heart rate
  • Confusion
  • Seizures


  • Julia Wilson, 'Cat World' Founder

    Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio

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