Introduction

Hyperkalemia refers to high blood potassium. There are many conditions, drugs and supplements that increase the risk of developing hyperkalemia. Here, we offer a quick guide to the fundamental facts you need to know.

Potassium is an important chemical; an essential participant in the function of muscle cells and nerves, particularly those that relate to the heart.

Blood potassium levels may be classified as follows:

• 3.6 – 5.2 mmol/L – normal
• > 5.2 mmol/ L – hyperkalemia

Levels higher than 5.2 mmol/L is what constitutes hyperkalemia.

Levels in excess of 6 mmol/L are classified as dangerous and are associated with a range of serious symptoms.

Symptoms of Hyperkalemia

Patients with mild hyperkalemia may present with few or no symptoms at all. As potassium levels rise, the risk of symptoms increases.

These symptoms include:

• Nausea
• Muscle pains and aches
• Muscle weakness
• Palpitations
• Numbness

In severe cases, hyperkalemia can cause cardiac disorders such as arrhythmias or cardiac arrest.

Hyperventilation may also occur to compensate metabolic acidosis, a potential cause of high blood potassium levels.

Causes

Whilst blood tests measure potassium levels, not all blood tests come back with accurate potassium results. Other factors may influence potassium values.

For example – it is not uncommon to see blood samples in which excess potassium escapes from blood cells (via hemolysis), artificially raising the result when the patient’s potassium level may be normal.

This is important. The patient may straddle the border between what constitutes “normal” and what defines “hyperkalemia”. Patients with elevated potassium levels may not display any symptoms, at least until potassium levels reach a certain point.

Hyperkalemia is most commonly caused by kidney disorders.

• Acute kidney injury
• Chronic kidney disease

Alternatively, hyperkalemia may be caused or exacerbated by the following drugs / supplements:

• ACE inhibitors
• Beta blockers
• Angiotensin receptor blockers – candesartan
• Potassium-sparing diuretics – amiloride, spironolactone, triamterene
• Potassium supplements
• Trimethoprim-sulfamethoxazole – Co-trimoxazole
• Pentamidine

Disease states can also cause hyperkalemia. These include:

• Addison’s disease
• Dehydration
• Severe injury or burns
• Type 1 diabetes
• Metabolic acidosis

Foods may also contribute to hyperkalemia. Foods high in potassium include:

• Avocados; Potatoes; Bananas; Oranges; Tomatoes; Nuts; Prunes; Apricots; Spinach; Broccoli.

Now that we understand the definition, causes and symptoms of hyperkalemia, let’s turn our attention to how the condition can be managed / treated.

Clinical considerations

Hyperkalemia is most often found when doctors are searching for, or are investigating, another illness or disease – for example: acute kidney injury or chronic kidney disease.

Once hyperkalemia has been diagnosed, the patient’s medicines should come under scrutiny to determine whether any medicine may contribute to or worsen their blood potassium levels.

Furthermore, treatment often depends on the underlying cause rather than focussing on potassium levels itself.

In more extreme cases, dialysis or emergency medicines may be deployed.

Beta-2 agonists – such as albuterol – are effective at rapidly reducing very high potassium levels. These drugs work to shift potassium ions from the extracellular to the intracellular compartment. Nebulised albuterolis not used in isolation; it may be used alongside other drugs, such as glucose, insulin and calcium gluconate, to rapidly reduce high blood potassium. Recall that this is an emergency treatment option until a more long-term therapeutic approach has been determined.

An ECG may be performed to establish the degree of arrhythmia risk.

As part of your NAPLEX exam, or any other clinical pharmacy or licensing exam, you are expected to have a thorough knowledge of hyperkalemia. Here, we’ve provided the most fundamental summary you need to know. Register to our online course today to receive instant access to pharmacologyquestions on hyperkalemia and other related topics.