Doctor's Notes on Hyperkalemia
(High Blood Potassium)
Hyperkalemia refers to the situation in which the blood level of potassium is abnormally high. An elevated level of potassium can have many causes. The main causes of a high potassium level are kidney problems or kidney failure, diseases of the adrenal gland, loss of potassium from inside of cells into the blood circulation, and taking certain medications.
In some cases, particularly with mild elevations of potassium, hyperkalemia does not produce symptoms (asymptomatic). In other cases, signs and symptoms of hyperkalemia include fatigue, nausea, muscle weakness, or tingling feelings. More serious symptoms of hyperkalemia can include a decreased in heart rate and weak pulse. Severe hyperkalemia can lead to heart stoppage and death. A rapid elevation in potassium level is usually more dangerous than one that rises slowly over time.
(High Blood Potassium) Symptoms
Hyperkalemia is a relatively common disturbance of electrolytes. Most cases of hyperkalemia are mild and may not produce any symptoms at all. Typically, hyperkalemia that develops slowly over time produces fewer symptoms than a sudden rise in potassium levels.
Usually, symptoms do not become apparent until potassium levels are very high (7.0 mEq/l or greater). Sometimes people with hyperkalemia report nonspecific symptoms such as muscle weakness, tiredness, tingling sensations, or nausea.
A slow heartbeat and weak pulse are more serious symptoms, since these may signal an effect on the electrical activity of the heart. Potassium is responsible for maintaining normal heart rhythm and hyperkalemia can have potentially life-threatening effects. While mild hyperkalemia probably has a limited effect on the heart, moderate hyperkalemia can change in the electrocardiogram (EKG, ECG) recording (EKG is an electrical reading of the activity of the neuromuscular activity of the heart), and severe hyperkalemia can cause the heart to stop beating.
Hyperkalemic periodic paralysis is a rare inherited disorder that can result in sudden hyperkalemia accompanied by muscle paralysis.
(High Blood Potassium) Causes
Excess potassium in the bloodstream can result from diseases of the kidneys or adrenal glands as well as from certain medications. Hyperkalemia can also be the result of potassium moving out of its usual location within cells into the bloodstream.
The majority of potassium within the body is located within cells, with only a small amount located in the bloodstream. A number of conditions can cause potassium to move out of the cells into the blood circulation, thereby increasing the measured level of potassium in the blood, even though the total amount of potassium in the body has not changed. Diabetic ketoacidosis, an emergency that can develop in people with type I diabetes, is an example of a condition in which potassium is drawn out of cells and into the bloodstream.
Similarly, any condition in which there is massive tissue destruction can result in elevated levels of blood potassium as the damaged cells release their potassium. Examples of tissue destruction include:
- surgical procedures,
- destruction of tumor cells or red blood cells, and
- rhabdomyolysis (a condition involving the destruction of muscle cells that is sometimes associated with muscle injury, alcoholism, or drug abuse).
Moreover, difficulty in drawing blood from veins for testing can traumatize red blood cells, releasing potassium into the serum of the blood sample to cause a falsely elevated reading of hyperkalemia on the blood test.
Any condition that decreases kidney function can result in hyperkalemia, since the kidneys rid the body of excess potassium by excreting it in the urine. Examples of conditions that decrease kidney function are glomerulonephritis, acute or chronic renal failure, transplant rejection, and obstructions within the urinary tract (such as the presence of stones).
The adrenal glands secrete many hormones important for proper body function. Among these is aldosterone, which regulates the retention of sodium and fluid in the kidneys along with the excretion of potassium in the urine. Diseases of the adrenal gland (such as Addison's disease, that causes a decreased aldosterone secretion) lead to a decrease in kidney excretion of potassium resulting in hyperkalemia.
Examples of medications that may lead to elevated potassium levels include:
- nonsteroidal anti-inflammatory drugs,
- ACE inhibitors,
- Angiotensin II receptor blockers (ARBs), and
- some types of diuretics.
Anyone Can Have It
This illness means you have a lower than normal red blood cell (RBC) count. Normal values vary; blood tests like the complete blood count (CBC) can be explained by your doctor. Anemia may also result from low levels of hemoglobin, the protein that transports oxygen to the body. No matter what the cause, less oxygen is available and this produces weakness, dizziness, and shortness of breath. It is treatable once the underlying cause is identified. Long-standing or severe lack of oxygen can damage of the brain, heart, and other organs.
The three main causes of the illness are inadequate or faulty production of red blood cells, a high rate of destruction of red blood cells, and excessive bleeding. Megaloblastic is one type of faulty red cell production. The condition of anemia may be mild and easily treatable or severe and require immediate intervention.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.