Serum Potassium



The monitoring of serum potassium can appreciate the blood level of a fundamental ke cation for muscle function like intestinal transit: potassium (K).

But it also allows monitoring of treatments could cause hypokalemia (in the case of diuretics, laxatives) or hyperkalemia (ACE inhibitor, anti-aldostérones, angiotensin II antagonists).

It is also an essential part of monitoring the diabetic patient, renal failure or carrying a heart disease.

This may be the end of the search for a primary or secondary aldosteronism before hypertension.


Kidney regulates the potassium levels; here is dose plasma concentrations.

Serum potassium

It is that of blood electrolytes. Sampling 5 mL of venous blood on heparin tube:

– Quickly send to the laboratory.

– Reduce to a minimum the time of the withers;

– Do not make a fist;

– Absolutely avoid hemolysis.


Normal values:

From 3.8 to 5 mEq / L.

Pathological changes:

– Hypokalaemia:

  – Medication: diuretics, laxatives, taking licorice,

  – Kidney disease,

  – Crohn’s disease,

  – Cushing’s disease,

  – Prolonged diarrhea;

– Hyperkalemia:

  – Medication: diuretics like spironolactone,

  – renal failure,

  – Adrenal insufficiency,

  – Addison’s disease,

  – Metabolic acidosis.



Practical advice:

Haemolysis, thrombocytosis or leukocytosis misrepresent hyperkalemia.

When hypokalemia is less than 3.5 mEq / L:

– If urinary potassium is less than 15 mEq / 24 h: this is the sign of extrarenal loss;

– If the kaliuresis than 15 mEq / 24 h, the loss is followed renal or taking diuretics.

When hyperkalemia is greater than 5.5 mEq / L, and the kaliuresis greater than 200 mEq / 24 h, there is a risk of serious cardiac disorders, which can lead to cardiac arrest.

Hypo- or hyperkalemia are biological emergencies: the transmission of results to the prescribing physician must be made as soon as possible.

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