The body requires potassium, an electrolyte, to function normally. Muscles and nerves rely on potassium to work correctly, and abnormal levels can have a negative effect on the heart, digestive system and kidneys. Most potassium in the body is stored in the cells. When potassium builds up in the blood, it becomes dangerous and possibly even fatal. A high potassium level in the blood creates a condition known as hyperkalemia. Normal levels are 3.5-5.0 mEq/L (milliequivalents per litre), and very high levels are anything above 7.0 mEq/L.
Kidney problems due to diabetes, glomerulonephritis, lupus nephritis, and acute or chronic kidney failure may cause a high level of potassium in the body. Hormone deficiencies related to problems with the adrenal gland, such as Addison's disease, traumatic injury, or tissue damage can also cause potassium build-up. A diet high in potassium or certain medications such as ACE (angiotensin converting enzyme) inhibitors, NSAIDs (non-steroidal anti-inflammatory drugs), angiotensin II receptor blockers and potassium-sparing diuretics can also cause increased potassium levels.
High potassium levels are difficult to diagnose because side effects may not be felt until the levels are dangerously high. Symptoms include nausea, fatigue, vomiting, muscle weakness or tingling in the fingers, toes or tongue. People have also reported a heavy feeling in the arms and legs, faintness, confusion, dizziness or shallow breathing. Severe hyperkalemia can result in diarrhoea, chest pain, heart palpitations or heart failure.
The most dangerous problem with high potassium is its potential to cause the heart to stop. Potassium causes changes in the electrical impulses in the heart muscles, which result in abnormal heart rhythms, cardiac arrhythmia or heart palpitations. If hyperkalemia is left untreated, the heart will stop as its electrical activity is suppressed. Signs of this can be a slow or weak pulse or chest pains.
High blood potassium levels in the blood adversely affect both the smooth muscles and the skeletal muscles. Potassium controls the production and storage of glycogen, which muscles use for energy. When high potassium affects the smooth muscles, such as those in the digestive system, nausea, vomiting, abdominal pain and diarrhoea can occur. Over time malnutrition can result, which will exacerbate the problem. When hyperkalemia is severe enough to effect the skeletal muscles, a condition called hyperkalemic periodic paralysis can occur. This paralysis is due to problems with electrical activity in the muscles, which can also cause feelings of weakness and tingling in the extremities. In severe cases of paralysis, hyperkalemia can cause problems with breathing as the muscles involved cease to function.
Potassium and sodium work together in the sodium-potassium pump to transmit electrical impulses along cells. When potassium levels are out of balance, the nerves cannot signal correctly, causing dizziness or faintness. In extreme cases, hyperkalemia can lead to convulsions or seizures as electrical activity is disrupted.
Treatment for high blood potassium levels focuses on stabilising the heart and promoting the movement of potassium back into the cells. The doctor may use insulin, glucose, beta agonists or sodium bicarbonate. Diuretics and binding resins can help excrete excess potassium. If the kidneys are not functioning correctly, dialysis can help filter excess potassium. Long-term treatment includes a change in diet to exclude foods high in potassium or medications to help decrease potassium levels. Your doctor will also treat any health conditions contributing to the problem.