What happens in hyperkalemia, exactly?

What is it?

Hyperkalemia means an elevated level of the ion potassium (K+) in the blood. The symptoms of hyperkalemia are hard to spot because of how general they are – they include a feeling of uneasiness, heart palpitations, and muscle weakness. Hyperkalemia is typically spotted while taking blood tests for another reasons. Severe hyperkalemia is a life-threatening condition, as it can lead to fatal arrhythmias of the heart.

Hyperkalemia is quite rare in healthy people, but it is detected in roughly 10% of hospitalized patients.

What causes it?

The kidneys are supposed to remove excess ions like potassium in the urine, which is why many cases of hyperkalemia are associated with kidney problems, such as acute kidney failure and chronic kidney disease. Some medications can also intervene with sufficient potassium removal,  some conditions can cause cells to excrete inappropriate amounts of potassium to the bloodstream, and sometimes ingesting things rich in potassium can be the cause.

What happens during it?

Cells maintain a membrane potential, which means that there is a difference in the electrical charges between the two sides of the membrane. This serves many functions, but one of the most important ones is that it allows neurons to conduct electrical signals. When a signal is provoked in the cell, ions start to flush to the other side of the membrane changing its potential, and this reaction is quickly spread throughout the length of the cell. Ions are needed for this, as they are the things that carry the electrical charge. Potassium is the most common positive ion found inside the cells.

If there’s too much potassium floating around on the “wrong” side of the membrane, the cell’s ability to use the membrane potential to its advantage decreases. Since this change affects practically every cell in the body, the symptoms of hyperkalemia are as non-specific as they are.

The heart has its own pacemaker which sends regular signals to the heart muscle cells, causing them to contract. Hyperkalemia is particularly dangerous if the elevated potassium levels cause this system to go wrong. If the heart doesn’t contract as it’s supposed to, cells don’t get enough oxygen and other vital molecules, and in this situation they won’t last for very long.

How can it be treated?

While treating the underlying cause of hyperkalemia is very important, in cases where there’s an urgent risk of heart trouble, the priority is to get the membrane potential to the level it’s supposed to be at as soon as possible.

Calcium ions can be administered and they have proven to be effective in the short term, even though the mechanism of this is not fully understood. Insulin and other substances can be used to transport the potassium to the inside of cells, so that the risk of complications is minimized for the time it takes to get the potassium out of the body.

The potassium can be eliminated from the body through a number of ways. Perhaps the most useful in severe cases are dialysis (purifying the blood from the things the kidneys are supposed to remove) or hemofiltration (passing the patient’s blood through a filtration circuit).

 

 

Sources: https://en.wikipedia.org/wiki/Hyperkalemia, http://emedicine.medscape.com/article/240903-overview?pa=H99R5pHCHr8WQekRtykK4j4dWiRahXA6%2Fnz2PUs0NpwolJeZwQkzUziRsgc4hF80NFsYxDuz%2Fz2hge3aAwEFsw%3D%3D#a4, http://www.mayoclinic.org/symptoms/hyperkalemia/basics/causes/sym-20050776, https://en.wikipedia.org/wiki/Membrane_potential, https://en.wikipedia.org/wiki/Hemodialysis, https://en.wikipedia.org/wiki/Hemofiltration

 

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