Hyperkalemia

Answer 1

Definition

Hyperkalemia is higher-than-normal levels of potassium in the blood.

Alternative Names

High potassium; Potassium - high

Causes, incidence, and risk factors

Potassium is involved in regulating muscle tissue, and is part of digestion, metabolism, and homeostasis (maintaining a balance between the many electrical and chemical processes of the body).

Hyperkalemia occurs when the level of potassium in the bloodstream is higher than normal. This may be related to an increase in total body potassium or the excess release of potassium from the cells into the bloodstream.

The kidneys normally remove excess potassium from the body. Most cases of hyperkalemia are caused by disorders that reduce the kidneys' ability to get rid of potassium.This may result from disorders such as:

• Acute kidney failure
• Chronic kidney failure
• Glomerulonephritis
• Obstructive uropathy
• Rejection of a kidney transplant

The hormone aldosterone regulates kidney removal of sodium and potassium. Lack of aldosterone can result in hyperkalemia with an increase in total body potassium. Addison's diseaseis one disorder that causes reduced aldosterone production.

Any time potassium is released from the cells, it may build up in the fluid outside the cells and in the bloodstream. Acidosis leads to the movement of potassium from inside the cells to the fluid outside the cells. Tissue injury can cause the cells to release potassium. Such injury includes:

• Burns
• Disorders that cause blood cells to burst (hemolytic conditions)
• Gastrointestinal bleeding
• Rhabdomyolysisfrom drugs, Alcoholism, coma, or certain infections
• Surgery
• Traumatic injury
• Tumors

If the kidney is working properly, and there is enough aldosterone, tissue trauma alone rarely leads to hyperkalemia. A normally functioning kidney will remove the excess potassium that has been released from the cells.

Increased intake of potassium can cause hyperkalemia if kidney function is poor. Salt substitutes often contain potassium, as do many "low-salt" packaged foods.

Hyperkalemia may be caused by medications, including medications that affect kidney function (potassium sparing diuretics, such as spironolactone, amiloride, or triamterene) and potassium supplements (especially intravenous potassium).

Symptoms

Hyperkalemia often has no symptoms. Occasionally, people may have the following symptoms:

• Irregular heartbeat
• Nausea
• Slow, weak, or absent pulse

Signs and tests

• ECG may show changes related to hyperkalemia
• ECG may show potentially dangerous arrhythmias:
  • Heart block that may become a complete heart block
  • Slower than normal heartbeat (bradycardia) that progressively slows
  • Ventricular fibrillation
• Pulse may be slow or irregular
• Serum potassiumis high

Treatment

Cardiac arrest (absent heartbeat) may occur at any time during the treatment of hyperkalemia. Hospitalization and close monitoring are required.

ACUTE TREATMENT

Emergency treatment is indicated if the potassium is very high, or if severe symptoms are present, including changes in the ECG.

The goal of acute treatment is to protect the body from the effects of hyperkalemia. Acute treatment may include:

• Cation-exchange resin medications, such as sodium polystyrene sulfonate (Kayexalate) -- to attach to potassium and cause it to be removed from the gastrointestinal tract
• Dialysis -- to reduce total body potassium levels, especially if kidney function is compromised
• Diuretic medications (water pills) -- to decrease total body potassium
• Intravenous calcium -- to temporarily treat muscle and heart effects of hyperkalemia
• Intravenous glucose and insulin -- to reverse severe symptoms long enough to correct the cause of the hyperkalemia
• Sodium bicarbonate -- to reverse hyperkalemia caused by acidosis

LONG-TERM TREATMENT

Long-term treatment includes treating the cause of the problem and disorders associated with hyperkalemia.

Treatment of chronic renal failure may include:

• Limiting potassium in the diet, including reducing or stopping potassium supplements
• Taking "loop diuretics" to reduce potassium and fluid levels in people with chronic renal failure

People with kidney failure or a history of hyperkalemia should not use a salt substitute as part of a low-salt diet.

Expectations (prognosis)

The outcome with this condition varies. In some people, the disorder causes deadly complications, while others tolerate it well.

Complications

• Arrhythmias
• Cardiac arrest
• Changes in nerve and muscle (neuromuscular) control

Calling your health care provider

Go to the emergency room or call the local emergency number (such as 911) if you have symptoms of hyperkalemia. Emergency symptoms include:

• Absent or weak heartbeat
• Changes in breathing pattern
• Loss of consciousness
• Nausea
• Weakness

Prevention

Treat disorders that may cause hyperkalemia promptly. Monitor serum potassium if you have one of these conditions.

Your doctor should assess your kidney function before and while you take potassium supplements. You should not take these supplements unless you have adequate urine output and kidney function.

References

Seifter JL. Potassium disorders. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 118.