Potassium deficiency and excess - causes and symptoms

Potassium is one of the most important elements necessary for life. It is an electrolyte. It is found inside every cell of the body, and its normal serum level ranges from 3.5 to 5.0 mmol/L. Both potassium deficiency and excess are common enough that it’s worth knowing how they manifest. Who is most at risk of having potassium levels that are too low or too high? What symptoms should you watch out for? When is it appropriate to take potassium supplements?

Potassium deficiency - causes

Potassium deficiency is usually not due to too little intake from the diet (although it can happen in people avoiding potassium-rich foods), but rather is a consequence of various physiological states and diseases. Potassium depletion is common in cases of chronic diarrhea and vomiting. In such situations, it is recommended to drink electrolyte solutions that replenish the essential minerals lost in excess along with water. Lack of potassium is also a frequent issue in malnourished individuals and those suffering from anorexia.

People who regularly take diuretics such as indapamide, hydrochlorothiazide, furosemide, or chlorthalidone (note: not all diuretics cause potassium loss through urine) or misuse diuretics against medical advice are also at risk of potassium deficiency, as this mineral is excreted along with urine.

Conditions that promote potassium deficiency include:

• kidney disease
• congenital kidney disorders
• adrenal cortex overactivity (Addison’s disease)
• hyperthyroidism
• congenital adrenal hyperplasia
• Cushing’s syndrome
• use of beta-agonist asthma medications
• use of high doses of insulin
• use of glucocorticosteroids
• extensive burns
• heavy sweating
• consumption of licorice

Potassium deficiency is relatively common, especially among people taking diuretics. Such medications are most often used by individuals with high blood pressure or heart failure. Up to 20% of them may experience too low potassium levels. If potassium deficiency is found and is not due to electrolyte loss from diarrhea, vomiting, or diuretics, a thorough diagnostic workup is needed to determine the primary cause of the drop in blood potassium.

Potassium deficiency - symptoms

Symptoms of potassium deficiency vary depending on how low the level is in the blood. Potassium deficiency can be:

• mild - serum potassium between 3.5 and 3.0 mmol/L
• moderate - 3.0 to 2.5 mmol/L
• severe - below 2.5 mmol/L

Mild potassium deficiency usually causes no symptoms. When the level falls below 3.0 mmol/L, there may be general weakness, muscle cramps (especially in the calves, often only at night), heart rhythm disturbances, irregular heartbeat, or palpitations. Constipation is also common, though it is not often linked to potassium deficiency.

Severe potassium deficiency can have serious, even life-threatening consequences. Symptoms include severe muscle weakness, muscle paralysis, intestinal paralysis (lack of peristalsis) leading to obstruction, sensory disturbances, tingling in the hands, face, and feet, low blood pressure, and dangerous heart arrhythmias. One symptom can closely resemble untreated diabetes – frequent urination and intense, unquenchable thirst.

Potassium excess - causes

High potassium is also a common health issue. Too much potassium usually occurs in people with severe acute or chronic kidney failure, diabetes, or heart failure who take medications that reduce potassium excretion in urine. Many cases are drug-related. Common culprits include angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, potassium-sparing diuretics (spironolactone, eplerenone, amiloride), nonsteroidal anti-inflammatory drugs (such as diclofenac, naproxen, ibuprofen, piroxicam), which are widely used painkillers and anti-inflammatories, and immunosuppressants.

Other situations that can increase potassium levels include:

• adrenal insufficiency
• excessive use of potassium supplements or potassium-containing medications
• high dietary potassium combined with reduced kidney excretion
• tumor lysis syndrome releasing large amounts of potassium
• breakdown of leukemia cells
• hemolysis
• diabetic ketoacidosis
• metabolic acidosis

Fighting potassium excess on your own is not recommended. If you suspect it, you should see a doctor.

Potassium excess - symptoms

Potassium excess is defined as serum potassium above 5.5 mmol/L. It can be classified as:

• mild (5.5–5.9 mmol/L)
• moderate (6.0–6.4 mmol/L)
• severe (above 6.5 mmol/L)

Symptoms are nonspecific, meaning the same signs can be caused by different conditions. High potassium is most noticeable when levels rise quickly. Slow increases may cause no symptoms, even with severe excess.

Symptoms may include:

• general weakness
• dizziness
• balance problems
• muscle weakness
• coordination issues
• difficulty standing up or climbing stairs
• quick fatigue
• paralysis of the lower limb muscles
• shortness of breath, trouble catching breath
• slow heart rate

A rapid increase in potassium can lead to cardiac arrest.

Potassium in tablets

It may seem that symptoms of potassium deficiency mean you should immediately take potassium supplements. However, unless the symptoms are clearly linked to diarrhea and vomiting (where increased potassium loss is certain), potassium tablets should not be taken without testing. This is because the symptoms of potassium deficiency and excess can be very similar. If you suspect potassium deficiency, see a doctor – and if your condition is serious, go to the emergency department or call an ambulance.

Before starting potassium supplements, it’s essential to check your serum potassium level. This is a quick and simple test that will confirm whether there is a deficiency and help determine the right dose. Taking potassium tablets “just in case,” for example because of calf cramps, is not a good idea. Cramps can be caused by many other reasons, and it’s easy to overdose potassium if you take it without need.