Hypokalemia is defined as a circulating potassium (K) level ≤ 4.0 mEq/L (normal is 4.4 - 6.1).
Blood potassium is normally regulated within normal ranges through intracellular pump actions and reduced levels in circulation reflect an abnormally large intracellular deficit.
Hypokalemia increases the resting membrane potential of cells, resulting in muscle weakness, impaired urine concentrating ability, polydipsia and arrythmias.
Blood potassium values are not always a reflection of total body potassium stores - potassium levels can be normal in blood, despite severe deficits in total body potassium.
Although hypokalemia is usually due to gastrointestinal or renal losses of potassium, other causes include:
- Babesia canis
- Xylitol toxicosis - concurrent hypokalemia and hyperphosphatemia
- Diuresis following furosemide
- Chronic renal disease
- Vomiting or diarrhea
- Dietary deficiency
- Stress induced
- Pseudohypokalemia due to severe lipemia
- Transcellular shift due to metabolic alkalosis
Clinical symptoms include cervical ventroflexion, lethargy, crouched gait, myalgia and reluctance to walk.
A diagnosis is based on low blood potassium. Urinalysis should be performed to exclude diabetes and renal causes of potassium loss.
Acute hypokalemia can be corrected with intravenous potassium chloride injections.
Glucose or insulin therapy should be avoided as this exacerbates the hypokalemia by increasing uptake into the intra-cellular fluid.
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