Hyperkalemia

Definition

Hyperkalemia occurs when the potassium level in the blood exceeds a certain level. If the potassium concentration in the blood serum exceeds 5 mmol/l, this is called excess in adults. The threshold value in children is 5.4 mmol/l.

Normally, the majority of potassium is found inside the cell. Only about two percent circulate in the so-called extracellular space. The difference in concentration serves to maintain the membrane potential between the inside and outside of the cells.

Even small changes in concentration have significant effects on the cardiovascular system and on the interaction of muscles and nerves. Such an electrolyte disturbance can be life-threatening. However, it is not only the concentration fluctuation alone that plays an important role, but also the speed at which it occurs.

The faster the serum potassium rises, the more serious are the consequences. The causes of an increase in potassium include various kidney diseases, such as acute renal failure, Addison’s disease and chronic renal insufficiency. Potassium, which is normally excreted, remains in the body.

Drugs can also cause hyperkalemia. In addition, changes in the pH value, extensive destruction of muscles or increased potassium intake lead to an excess of electrolytes. Incorrectly high values when taking blood samples are due to potassium leaking from burst red blood cells.

These are the symptoms of hyperkalemia

Hyperkalemia is an emergency situation, as in the worst case it can lead to a severe cardiac arrhythmia and cardiac arrest. The following symptoms are typical of the disease and should be diagnosed accurately. The heart can be thrown out of rhythm by many causes.

One cause is hyperkalemia. The excessive amount of potassium leads to a permanent excitation of the cell walls of the heart muscle cells. The permanent excitation then ensures that the cells enter the resting phase in a disorderly manner and are no longer regularly controlled.

This leads to irregular heartbeats and irregular blood flow through the body. This can lead to so-called ventricular fibrillation, which is equivalent to cardiac arrest, as the heart beats too fast to pump blood through the body. Acidosis is a hyperacidity of the blood.

The pH value, which indicates how acidic the blood is, is within a narrow range and deviations can have serious consequences. In acidosis, the body tries to balance the value via the kidneys. This means that acidic protons are excreted.

However, the kidneys can only do this in direct exchange for potassium ions. For each proton that is released, the body absorbs one potassium ion. The amount of potassium in the blood rises, leading to hyperkalemia with the corresponding consequences.

Bradycardia, i.e. a slowed heartbeat, can have many causes. Bradycardia is a cardiac arrhythmia. An excess of potassium can cause certain ion channels in the heart muscle cells to be disordered in a kind of resting period.

As a result, the heartbeats are no longer triggered regularly. This can lead to various cardiac dysrhythmias, which include bradycardia. In the electrocardiogram, or ECG for short, the doctor can detect certain heart diseases.

The patterns in the ECG are typically shaped for certain disorders, including hyperkalemia. The first things that stand out are irregular heartbeats and the so-called tent-shaped T. This is the last wave of a complete heart rhythm complex. If there is a large excess of potassium, the other waves in the ECG also change.

In case of ventricular fibrillation, which can be a consequence of hyperkalemia, the ECG shows very fast disordered waves. An ECG can be written both routinely at the family doctor’s office and for permanent monitoring in hospital. A metallic taste in the mouth can be caused by various diseases and medication.

In cases of kidney failure, patients often report a metallic taste. Kidney failure is one of the most common causes of hyperkalemia and therefore patients with hyperkalemia also frequently report a change in taste. However, the metallic taste is not directly triggered by potassium in the oral cavity.

The affected person therefore does not taste potassium, but the sensory perception of taste changes overall. Hyperkalemia is characterized by very unspecific symptoms and is usually not associated with pain. However, some affected persons may find the tingling in the fingers, which is typical of hyperkalemia, very unpleasant and therefore report pain.Acute kidney failure due to inflammation, which can be a cause of hyperkalemia, can also cause severe pain in the kidney area.

However, these are not the consequence of hyperkalemia. Since hyperkalemia always occurs in the context of other diseases, it can be difficult to assign a symptom such as fatigue to a specific cause. In most cases, however, hyperkalemia is not the cause, but an additional symptom in addition to fatigue.

Much more typical is fatigue in hypokalemia, i.e. when the potassium level drops. Constipation is also more of a symptom of hypokalemia. This means that the person concerned has too little potassium in the blood.

Constipation is unusual for hyperkalemia. However, since many symptoms are due to the underlying disease and not to hyperkalemia, constipation can occur at the same time as hyperkalemia. This is possible, for example, with tumor diseases in the intestine.

With some therapies, the tumor can be attacked so quickly that the tumor dissolves and the components lead to disturbances in the salt and water balance of the body. One of the two typical symptoms of hyperkalemia is muscle weakness. This affects both the skeletal muscles and the heart muscles.

The increased potassium opens up ion channels in the cell membranes. After each opening, the channels go to rest for a short time. Due to the increased amount of potassium, this cycle comes out of rhythm and the cells receive different information.

In the case of skeletal muscles, this leads to the fact that those affected can apply less strength. Hyperkalemia is an absolute emergency and can have serious consequences for the body within a short time. After the rather unspecific early symptoms, a cardiac arrhythmia with a heart beating too slowly occurs.

This slow heartbeat can no longer supply the body with sufficient oxygen-rich blood. The brain needs large amounts of oxygen and even a slight deficiency can trigger a disturbance of consciousness. This is a protective mechanism of the body, as the brain uses less oxygen in a resting mode.