Hyperkalemia is a metabolic disorder in which there is an elevated concentration of potassium in the blood. Potassium is necessary for proper functioning of the nerves and muscles, including the heart muscle, but an excess of the electrolyte may be life-threatening. Normally, almost all potassium in the body is found in the cells and organs with very little circulating in the bloodstream.
Since the kidneys regulate potassium levels in the body, when kidney disease is present, the potassium level can elevate, causing a dangerous medical situation. While there are other causes of hyperkalemia, kidney disease is the most common. Mild hyperkalemia is usually tolerated well by the patient and resolves quickly. Severe hyperkalemia is a medical emergency since it can result in death from an abnormal heartbeat, known as an arrhythmia.
Causes of Hyperkalemia
While kidney disease is the most common cause of hyperkalemia, there are several other possible causes. Some involve potassium being sifted out of cells into the blood. All involve the inability to eliminate excess potassium from the blood through the urine. These causes may include:
- Diseases of the adrenal glands, such as Addison's disease
- Hormonal disorders
- Lupus or diabetes
- Excessive potassium in the diet
- Any medications that interfere with urine output
- Blood transfusions
- Potassium chloride, a compound used in lethal injections
- Alcoholism or heavy drug use
- Traumatic injury involving bleeding or burns
When a patient has blood drawn, a condition called pseudohyperkalemia may occur. This happens when there is excessive leakage of potassium from the cell membranes during or after the blood is drawn. Pseudohyperkalemia is not considered abnormal, however, since it is a temporary, controlled condition.
Symptoms of Hyperkalemia
The symptoms of hyperkalemia may be vague and difficult to pinpoint, often including a general feeling of uneasiness or malaise. Other symptoms may include:
- Palpitations caused by heart arrhythmia
- Slow heart rate or weak pulse
- Muscle weakness or fatigue
- Tingling or numbness of the skin
- Breathing disturbances
People with hyperkalemia may suddenly collapse if their heartbeat gets very low or even stops.
Complications of Hyperkalemia
Patients with hyperkalemia are at risk from heart arrhythmias which may precipitate a heart attack. Hyperkalemia may also cause a dangerous heart condition known as ventricular fibrillation in which the lower chambers of the heart flutter instead of pumping blood. Since the balance of potassium in the body is a delicate one, there is also a risk that treatment for hyperkalemia will result in too low a level of potassium in the blood, or hypokalemia.
Diagnosis of Hyperkalemia
Hyperkalemia may be difficult to diagnose because of the nonspecific nature of the presenting symptoms. After a thorough physical examination, the physician will take a full history to investigate the patient's diet and to check any medications or supplements the patient may be taking.
Blood tests and urinalysis will be conducted to determine potassium levels. In addition, the doctor may order an electrocardiogram, or EKG, to check the electrical activity of the patient's heart. Not every patient with hyperkalemia has notable changes on an EKG.
Treatment of Hyperkalemia
Hyperkalemia can be treated in several ways, depending on its severity. Unless it is very mild, treatment may include hospitalization and one or more of the following:
- Discontinuation of medications that increase blood potassium levels
- Calcium, sodium bicarbonate or other medications administered intravenously
Glucose and insulin may also be administered intravenously. Long-term treatment may include a diet with restricted potassium content to both prevent and treat high potassium levels.