What controls blood potassium levels?
Blood potassium levels are controlled by several mechanisms:
Hormonal regulation
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Aldosterone: Produced by the adrenal glands, this hormone regulates potassium excretion in the urine. High aldosterone levels increase potassium excretion, lowering blood potassium
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Insulin: Helps facilitate potassium uptake in cells, reducing blood potassium levels.
Renal regulation
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Kidney function: Potassium is filtered by the kidneys and excreted in urine. Hence impaired kidney function (AKI or CKD) can lead to hyperkalaemia (high blood potassium).
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Renin-angiotensin-aldosterone (RAS) system: regulates electrolyte balance, including potassium (and sodium).
Cellular mechanisms
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Potassium channels: Regulate potassium entry and exit from cells
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Sodium-potassium pump: Maintains cellular potassium levels by pumping sodium out and potassium in.
Other factors
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Hormonal balance: hormones other than aldosterone) affect potassium balance – e.g. cortisol, catecholamines, and TSH
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Acid-base balance: changes in pH levels push potassium in and out of the cells (out from, or into, the bloodstream)
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Medications: certain drugs (e.g. diuretics) affect potassium levels (high and low).
Dietary factors
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Potassium intake: Consuming potassium-rich foods (fruits, vegetables, whole grains) increases blood potassium
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Sodium-potassium balance: Excessive sodium intake can disrupt potassium balance.
Note. These have relatively little effect on blood potassium levels.
Regulatory organs
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Kidneys: Filter and excrete potassium
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Adrenal glands: Produce aldosterone
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Pancreas: Releases insulin
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Pituitary gland: Regulates hormone balance (e.g, via ADH).
Clinical significance
- Mild hypokalaemia or hyperkalaemia is asymptomatic (i.e. ‘silent’)
- Very abnormal potassium levels (hypokalaemia or hyperkalaemia) can lead to cardiac arrhythmias, muscle weakness, and respiratory failure.
