Symptoms of hyperkalemia are fatigue, nausea, breathing problems and palpitations, according to Healthline. In very severe cases, the patient may have a weak pulse, or his heart may stop altogether, reports MedicineNet.
Hyperkalemia symptoms depend on the level of potassium in the blood, and the patient may not experience any symptoms if the potassium levels in his blood are not significantly high, notes Healthline. The patient may also experience fewer symptoms if his hyperkalemia develops over time than if his potassium levels rise abruptly, reports eMedicineHealth.
Some hyperkalemia patients report vague symptoms, such as nausea, muscle weakness, fatigue and tingling sensations, reports MedicineNet. Some patients also have symptoms that reflect the medical condition that caused levels of potassium to rise in the body.
Since potassium helps maintain normal heart rhythm, high potassium levels can have an effect on the heart, according to eMedicineHealth. Moderate hyperkalemia may result in changes in electrocardiogram readings. Severe hyperkalemia may cause fatal cardiac standstill, reports MedicineNet.
Hyperkalemia can also affect how skeletal muscles function, according to MedicineNet. Individuals who suffer from hyperkalemic periodic paralysis, a rare and inherited disease, may experience a sudden increase in potassium levels in their blood followed by muscle paralysis. The cause of the paralysis is not known, though it may be that hyperkalemia suppresses the muscle's electrical activity.