Hyperkalemia

Hyperkalemia or high potassium level occurs when the level of potassium in your body and blood is higher than normal.
Potassium is a nutrient that is critical to the normal function of nerve, heart and muscles cells. It plays an important role in controlling activity of smooth muscle  and skeletal muscle, as well as the muscles of the heart. It is also important for normal transmission of electrical signals throughout the nervous system within the body.
Normal blood potassium level is 3.6 to 4.8 milliequivalents per liter (mEq/L). Having a blood potassium level higher than 6.0 mEq/L can be dangerous and requires immediate treatment. Extremely high levels of potassium in the blood (severe hyperkalemia) can lead to cardiac arrest and death.

The most important clinical effect of hyperkalemia is related to electrical rhythm of the heart. While mild hyperkalemia probably has a limited effect on the heart, moderate hyperkalemia can produce EKG changes (EKG is an electrical reading of the heart muscles), and severe hyperkalemia can cause suppression of electrical activity of the heart and can cause the heart to stop beating.

Another important effect of hyperkalemia is interference with functioning of the skeletal muscles. Hyperkalemic periodic paralysis is a rare inherited disorder in which patients can develop sudden onset of hyperkalemia which in turn causes muscle paralysis. The reason for the muscle paralysis is not clearly understood, but it is probably due to hyperkalemia suppressing the electrical activity of the muscle.

Hyperkalemia can be asymptomatic, meaning that it causes no symptoms. Sometimes, patients with hyperkalemia report vague symptoms including:

  • nausea
  • fatigue
  • muscle weakness
  • tingling sensations

Serious symptoms of hyperkalemia include slow heartbeat and weak pulse. Generally, a slowly rising potassium level (such as with chronic kidney failure) is better tolerated than an abrupt rise in potassium levels. Unless the rise in potassium has been very rapid, symptoms of hyperkalemia are usually not apparent until potassium levels are very high (typically 7.0 mEq/l or higher).

Symptoms may also be present that reflect the underlying medical conditions that are causing the hyperkalemia.

The most causes of hyperkalemia are kidney dysfunction, diseases of the adrenal gland, potassium sifting out of cells into the blood circulation, and medications. Potassium is normally excreted by the kidneys, so disorders that decrease the function of the kidneys can result in hyperkalemia.
Furthermore, patients with kidney dysfunctions are especially sensitive to medications that can increase blood potassium levels. For example, patients with kidney dysfunctions can develop worsening hyperkalemia when given salt substitutes that contain potassium, when given potassium supplements (either orally or intravenously), or medications that can increase blood potassium levels. Examples of medications that can increase blood potassium levels include:

* ACE inhibitors
* nonsteroidal anti-inflammatory drugs (NSAIDs)
* Angiotensin II Receptor Blockers (ARBs)
* potassium-sparing diuretics

Another cause of hyperkalemia is tissue destruction, dying cells release potassium into the blood circulation. Examples of tissue destruction causing hyperkalemia include:

  • trauma
  • burns
  • surgery
  • hemolysis
  • massive lysis of tumor cells
  • rhabdomyolysis (a condition involving destruction of muscle cells that is sometimes associated with muscle injury, alcoholism, or drug abuse).

Sometimes a report of high blood potassium isn’t true hyperkalemia. Instead it may be caused by the rupture of blood cells in the blood sample during or shortly after drawing the sample. The ruptured cells leak their potassium into the sample. This falsely raises the amount of potassium in the blood sample, even though the potassium level in your body is actually normal. When this is suspected, a repeat blood sample is done.

Hyperkalemia diagnosis is made by a doctor or medical professional.
In order to gather enough information for diagnosis, the measurement of potassium needs to be repeated, as the elevation can be due to hemolysis in the first sample. The normal serum level of potassium is 3.5 to 5 mEq/L. Generally, blood tests for renal function (creatinine, blood urea nitrogen), glucose and occasionally creatine kinase and cortisol will be performed. Calculating the trans-tubular potassium gradient can sometimes help in distinguishing the cause of the hyperkalemia.
In many cases, renal ultrasound will be performed, since hyperkalemia is highly suggestive of renal failure.
Also, electrocardiography (EKG/ECG) may be performed to determine if there is a significant risk of cardiac arrhythmias.

Treatment methods vary extensively based on certain factors such as the severity of the hyperkalemia, and others. Any given case of hyperkalemia may require different treatment. The severity of the elevated potassium and its complications, the patient, and other factors may be considered.
Below, several of the potential treatment measures are considered.

Calcium supplementation
This is generally given through a central venous catheter, since the calcium could cause phlebitis. Although it does not lower the levels of potassium in the individual’s blood, it does lower the excitability of the cardiac muscle, which is an attempt to avoid cardiac arrhythmias. Other treatment methods are used in actual attempts to reduce the elevated potassium levels.

Dialysis
In cases that are severe or difficult to deal with, some potassium may need to be removed from the patient through dialysis. Dialysis is essentially artificial kidney function, part of which is maintaining a balance of water and minerals, one of which is potassium.

Bicarbonate therapy
This method is sometimes used in case involving metabolic acidosis, a serious process that if left untreated can bring on acidemia, and eventually coma and death. The bicarbonate ion is intended stimulate a cellular exchange.

Insulin
Injected by IV, generally accompanied by 50ml of 50% dextrose to avoid hypoglycemia in the patient, insulin is intended to be used in a process to change potassium ions into cells.

Prevention of hyperkalemia
In an attempt to stop hyperkalemia from recurring, certain prevention methods can be taken. A diuretic may be taken by the patient, and potassium in the diet may be lowered, along with stopping any offending medicines, if the patient can do so. Other methods may also be considered.