Hyperkalemia (High Level of Potassium in the Blood)
(See also Overview of Potassium's Role in the Body.)
In hyperkalemia, the level of potassium in blood is too high.
A high potassium level has many causes, including kidney disorders, drugs that affect kidney function, and consumption of too much supplemental potassium.
Usually, hyperkalemia must be severe before it causes symptoms, mainly abnormal heart rhythms.
Doctors usually detect hyperkalemia when blood tests or electrocardiography is done for other reasons.
Treatment includes reducing consumption of potassium, stopping drugs that may cause hyperkalemia, and using drugs to increase potassium excretion.
Potassium is one of the body's electrolytes, which are minerals that carry an electric charge when dissolved in body fluids such as blood. The body needs potassium for nerve and muscle cells to function, but too much potassium can also interfere with function.
Usually, hyperkalemia results from several simultaneous problems, including the following:
The most common cause of mild hyperkalemia is the use of drugs that decrease blood flow to the kidneys or prevent the kidneys from excreting normal amounts of potassium. Kidney failure can cause severe hyperkalemia on its own. Addison disease can also cause hyperkalemia.
Hyperkalemia can develop after a large amount of potassium is released from the cells. The rapid movement of potassium from cells into blood can overwhelm the kidneys and result in life-threatening hyperkalemia.
By itself, increased intake of potassium does not often cause hyperkalemia because normal kidneys do a good job in excreting any extra potassium.
What Makes the Potassium Level Increase?
Mild hyperkalemia causes few, if any, symptoms. Sometimes, people may develop muscle weakness. In a rare disorder called hyperkalemic familial periodic paralysis, people have attacks of weakness that can progress to paralysis.
When hyperkalemia becomes more severe, it can cause abnormal heart rhythms. If the level is very high, the heart can stop beating.
Usually, hyperkalemia is first detected when routine blood tests are done or when a doctor notices certain changes on an electrocardiogram (ECG).
To identify the cause, doctors evaluate a person's medical history, determine which drugs people have been taking, and do blood tests to check for evidence of diabetes mellitus, acidosis, muscle breakdown, or kidney disorders.
The disorder that is causing hyperkalemia is treated.
For mild hyperkalemia, reducing consumption of potassium or stopping drugs that prevent the kidneys from excreting potassium may be all that is needed. If the kidneys are functioning, a diuretic that increases potassium excretion may be given. If needed, a resin that absorbs potassium from the digestive tract and passes out of the body in the stool can be given by mouth or enema. Sodium polystyrene sulfonate is a potassium-absorbing resin that is effective but used only for short periods because it can cause excess sodium to be retained. Patiromer is a new resin drug that can be used for longer periods. It is useful for people who require drugs that usually raise potassium levels, such as angiotensin-converting enzyme (ACE) inhibitors for treatment of heart or kidney disease.
For moderate to severe hyperkalemia, the potassium level must be reduced immediately. Doctors monitor the heart continuously during treatment. Calcium is given intravenously to protect the heart but does not lower the potassium level. Then insulin and glucose are given, which move potassium from blood into cells, thus lowering the potassium level in blood. Albuterol (used mainly to treat asthma) may be given to help lower the potassium level. It is inhaled.
If these measures do not work or if people have kidney failure, dialysis may be necessary to remove the excess potassium.