Potassium, serum
S-K KL 2001
Potassium serves as the primary intracellular cation, with approximately 98% of it residing inside the cells. Its presence plays a crucial role in regulating cell volume and maintaining the acid-base balance. Aside from its involvement in conducting nerve impulses, potassium also plays a vital role in regulating muscle contractions, making it essential for maintaining the normal rhythm of the heart. The kidneys are highly effective in regulating the body’s potassium balance.
Indications
Monitoring of fluid and electrolyte balance, acid-base balance and diuretic medication. Assessment of fluid balance and acid-base balance.
Sample
1.0 mL of serum (min. 0.5 mL). A hemolysed sample is not valid. To prevent hemolysis, it is crucial to separate the sample as soon as possible after sampling.
Storage and delivery
Delivery at room temperature, if it arrives within 24 hours. Can be stored refrigerated over the weekend.
Method
Ion selective electrode (ISE). Accredited method.
Turnaround time
1 – 2 weekdays
Reference ranges
Adults, 3,5 – 5,1 mmol/L
Under 16 yrs, 3,3 – 5,2 mmol/L
Interpretation of results
Hyperkalemia, an increased serum potassium concentration, can result from excessive release of potassium from cells or reduced excretion through the kidneys. Cell destruction, acidosis, and intense physical exertion can lead to potassium release. Kidney and RAA system dysfunction, as well as drugs like ACE inhibitors used for heart and blood pressure conditions, and diuretics like spironolactone, can also cause hyperkalemia. A rarer cause is adrenal insufficiency or Addison’s disease.
Symptoms of hyperkalemia become noticeable when potassium concentration rises above 5.5 mmol/l. These symptoms may include fatigue, muscle weakness, cardiac arrhythmias, and signs of paralysis.
On the other hand, hypokalemia, low potassium levels, usually occurs due to potassium loss from the body. Common reasons include the use of diuretics, vomiting, diarrhea, or excessive laxative use. Severe malnutrition and anorexia leading to low potassium intake can also cause hypokalemia. Less common causes are hyperaldosteronism, Cushing’s syndrome, renal tubule damage, or excessive consumption of licorice.
Hypokalemia can also be associated with magnesium deficiency.
Even mild hypokalemia can increase the risk of cardiac arrhythmias, while severe hypokalemia can be dangerous, leading to weakness, muscle weakness, and cardiac arrhythmias.
Inquiries
martin.tornudd@milalab.fi
Last update 8.8.2023
