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Hyperkalemia
(High Blood Potassium)

Hyperkalemia Overview

Hyperkalemia is an excessive level of potassium in the bloodstream. Potassium has several important functions in the body. It is essential for the normal functioning of the muscles, heart, and nerves. Potassium helps the body regulate activity of muscle, including the smooth muscle (involuntary muscles, such as the muscles found in the digestive tract), skeletal muscle (voluntary muscles, such as muscles of the extremities and torso), and the muscle of the heart. It is also important for maintaining normal heart electrical rhythm and for normal electrical signals in the nervous system.

  • The normal potassium level in the blood is 3.5-5.0 milliEquivalents per liter (mEq/L).

  • Potassium levels between 5.1 mEq/L to 6.0 mEq/L are considered to be mild hyperkalemia.

  • Potassium levels of 6.1 mEq/L to 7.0 mEq/L are moderate hyperkalemia, and levels above 7 mEq/L reflect severe hyperkalemia.

Hyperkalemia 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 (about 98%) is located within cells, with only 2% 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:

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 antiinflammatory drugs,

  • ACE inhibitors,

  • Angiotensin II receptor blockers (ARBs), and

  • some types of diuretics.


Next: Hyperkalemia Symptoms »

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Hyperkalemia (High Blood Potassium)

Electrolytes Overview

Electrolytes are the smallest of chemicals that allow the body to work. Electrolytes such as sodium, potassium, and others are critical in allowing cells to function. They generate electricity, contract muscles, move water and fluids within the body, and participate in myriad other activities.

The concentration of electrolytes in the body is controlled by a variety of hormones, most of which are manufactured in the kidney and the adrenal glands. Sensors in specialized kidney cells monitor the amount of sodium, potassium, and water in the bloodstream. The body functions in a very narrow range of normal, and it is hormones like renin (made in the kidney), angiotensin (from the lung, brain and heart), aldosterone (from the adrenal gland), and antidiuretic hormone (from the pituitary) that keep the electrolyte balance within those limits.

Keeping electrolyte concentrations in balance also includes stimulating the thi...

Read the Electrolytes article »



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