FrançaisNormal potassium levels
Most of the body’s potassium is inside cells, mainly muscle: only about 5% is in the fluid outside them, so the blood value does not always reflect the body’s stores [1]. mEq/L and mmol/L give the same number for potassium [1].
| Species | Potassium (mmol/L) |
|---|---|
| Dog | 3.9–5.1 |
| Cat | 3.7–6.1 |
How to read the potassium line
Here is an example line from a cat’s chemistry panel.
- Abbreviation K, K⁺ or potassium, usually in the electrolyte block with sodium (Na) and chloride (Cl).
- Result 3.1 mmol/L in this illustrative line: mildly low.
- Unit mmol/L or mEq/L: the same number for potassium [1].
- Laboratory interval The example uses the cat interval of the Merck Veterinary Manual [2].
- Flag L: below the interval. In an older cat, your vet looks at the kidney values and the cat’s muscle strength [1].
High potassium: first rule out the sample
- Serum versus plasma. Platelets release potassium when blood clots, so serum can read up to 0.7 mmol/L higher in dogs and 1.6 mmol/L higher in cats than plasma [1].
- Delayed separation. Potassium leaks out of cells if the sample waits. Akitas, Shiba Inus and some other Japanese breeds have potassium-rich red cells, so haemolysis raises their result [1].
- EDTA contamination. A very high potassium (above 10 mmol/L) with a very low calcium suggests the sample touched the purple-top tube’s anticoagulant [1].
True high potassium (hyperkalemia)
High potassium makes heart cells over-excitable: the most serious effect is an abnormal heart rhythm, which can be life-threatening [1].
- Urinary blockage or rupture, for example a male cat that cannot urinate [1].
- Acute kidney failure with little or no urine [1].
- Addison’s disease in dogs, typically with a low sodium; it is confirmed with an ACTH stimulation test [1].
- Tissue damage or diabetic crisis, which shift potassium out of cells [1].
Low potassium (hypokalemia)
Low potassium usually comes from losses through the gut (vomiting, diarrhoea) or the kidneys. It causes muscle weakness and heart rhythm changes, and reduces the kidneys’ ability to concentrate urine [1].
- Chronic kidney disease in cats, through losses in the urine [1].
- Diet: cats fed low-potassium diets can become hypokalemic [1].
- Diabetes and its treatment: insulin pushes potassium into cells [1].
- Hyperaldosteronism, a rare adrenal disease of middle-aged and older cats, with muscle weakness, a drooping neck (ventroflexion) and high blood pressure [1, 3].
- Burmese and related breeds: an inherited form causes episodes of weakness in young cats, often with the head bent down [4].
Results often read with potassium
En français : le potassium et le phosphore chez le chat.
Questions to ask your veterinarian
- Could the sample type or a delay explain this potassium result?
- Should we repeat it on a heparin (plasma) sample?
- Do the kidney values explain a low potassium in my cat?
- Is potassium supplementation needed, and how will we monitor it?
- Should my dog have an ACTH stimulation test?
Get the electrolytes explained with the rest of the report.
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Frequently asked questions
What are the signs of high potassium in dogs?
Weakness, collapse and a slow or irregular heartbeat. A urinary blockage or Addison’s disease are typical causes, and both need urgent care [1].
What causes low potassium in cats?
Most often losses through the kidneys in chronic kidney disease, or through vomiting and diarrhoea. Low-potassium diets and, rarely, an adrenal tumour are other causes [1].
What level of potassium is dangerous?
There is no single cut-off: the speed of change and the heart rhythm matter. A markedly high or low value, or one with weakness or heart rhythm changes, needs prompt care [1].
How is low potassium corrected?
With potassium supplements by mouth or in a drip, chosen and monitored by your vet. Do not give supplements without advice.
Can a high potassium result be wrong?
Yes. Clotting, a delayed or haemolysed sample, or EDTA contamination can all raise it falsely. Your vet may repeat it on a plasma sample [1].
Sources
- eClinPath, Cornell University College of Veterinary Medicine. Potassium. eclinpath.com/chemistry/electrolytes/potassium
- Merck Veterinary Manual. Serum biochemical analysis reference ranges. merckvetmanual.com/reference-values-and-conversion-tables/reference-guides/serum-biochemical-analysis-reference-ranges
- Lo AJ et al. Treatment of aldosterone-secreting adrenocortical tumors in cats by unilateral adrenalectomy: 10 cases (2002-2012). J Vet Intern Med. 2014;28(1):137-143. doi.org/10.1111/jvim.12186
- Malik R et al. Periodic hypokalaemic polymyopathy in Burmese and closely related cats: a review including the latest genetic data. J Feline Med Surg. 2015;17(5):417-426. doi.org/10.1177/1098612X15581135
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.