Hyperkalemia is a condition where the potassium level in an individual's blood is higher than normal, according to Mayo Clinic. The most common cause of hyperkalemia is a loss of kidney function due to either acute kidney failure or chronic kidney disease.
A normal potassium level in blood is 3.5 to 5.0 millimoles per liter, states MedicineNet. Doctors consider potassium levels between 5.0 and 6.0 millimoles per liter to signal mild hyperkalemia, while those with levels greater than 7.0 millimoles per liter have severe hyperkalemia. Severe hyperkalemia, when not diagnosed and treated, can result in cardiac arrest and death.
Potassium is a vital nutrient in the body for the proper functioning of muscles, nerves and the heart, explains MedicineNet. Not only does it aid in the transmission of electrical signals across nerves, but it also controls and regulates muscle activity, including that of the heart. Therefore, the effects of hyperkalemia mostly relate to heart function. Severe hyperkalemia can suppress the electrical activity of the heart, causing either abnormal heart rhythms or total heart stoppage.
In some cases, hyperkalemia can also suppress the electrical activity of skeletal muscles, causing muscle paralysis, notes MedicineNet. Mild hyperkalemia, however, can exhibit no symptoms, though some patients report general nausea, fatigue and weakness.