What is hyperkalemia?
The presence of higher than normal levels of potassium in the blood is described as hyperkalemia. It is primarily an indicator of kidney dysfunction rather than being a disease by itself. It can also occur with increased intake of potassium rich substances. The normal levels of potassium in blood lie in the range of 3.6 -5.2mmoles/L.
In patients with renal diseases, either primary or caused by conditions like diabetes, the potassium levels could rise above 5.3mmoles/L. Hyperkalemia with potassium levels above 7mmoles/L is potentially life-threatening and requires immediate medical attention. Although it can affect both men and women, it is more frequently seen in males. Conversely, hypokalemia (low blood potassium levels) is more common in women. The reason for this gender difference is unclear. (1)
Symptoms of High Blood Potassium
Potassium is the major intracellular cation (positively charged ion). Its relative distribution inside and outside the cells is critical for the functioning of nerves and muscles. Therefore, hyperkalemia affects the neuromuscular system and this could manifest as muscle weakness and numbness or tingling sensations in the body. There may be nausea, malaise and palpitations.
Chronic hyperkalemia affects the heart muscles resulting in slow heartbeat, weakening of pulse and arrythmia (irregular heartbeat) which could even be fatal. In hyperkalemia caused by Addison’s disease, a person may experience abdominal pain, hyperpigmentation and hypoglycemia.
Causes of Hyperkalemia
Potassium from dietary intake is completely absorbed along the gastrointestinal tract. Urine serves as the major vehicle for clearance of excess potassium from blood. The regulation of potassium reabsorption occurs in the distal region of nephrons (the functional units of kidneys), under the influence of the hormone, aldosterone. Hyperkalemia is caused by the following factors that disturb potassium homestasis (maintenance of steady-state) :
- Excessive dietary intake of potassium-rich foods (meat, beans, fruits). Fad diets can sometimes be the cause of unusual dietary habits that can lead to an excessive intake of only these foods that are abundant in potassium.
- Certain supplements which have high levels of potassium.
- Acute and chronic kidney failure due to glomerulonephritis, lupus nephritis, urolithiasis (kidney stones) or kidney transplant rejections
- Diabetic nephropathy which is the damage to the kidneys that arises with long term diabetes mellitus.
- Addison’s disease which affects the adrenal gland and decreases the production of aldosterone.
- Hemolysis which is destruction of red blood cells.
- Medications such as angiotensin-converting enzyme (ACE) inhibitors, non-steroidal anti-inflammatory drugs (NSAIDs) or potassium-sparing diuretics (spironolactone, triamterene).
- Rhabdomyolysis or rupturing of muscles due to excessive consumption of alcohol or drug abuse.
Treating High Potassium Levels
Hyperkalemia results in cardiac abnormalities. Therefore, in addition to blood tests for estimation of potassium levels, hyperkalemia is diagnosed by electrocardiograms (ECGs). The primary goal of treatment is to restore the potassium levels to normality and prevent complications. This involves :
- Insulin injections to facilitate the cellular uptake of potassium.
- Other drugs that increase the entry of potassium into cells (salbutamol, bicarbonate therapy).
- Calcium injections for protectingof heart and muscles.
- Diuretics (furosemide, hydrocholorothiaizde) to increase the excretion of excess potassium in urine.
- Administration of cation-exchange resins which favor excretion of potassium in stools (sodium polystyrene sulphate with sorbitol).
- Reducing potassium intake either in food or as supplements.
- Discontinuing medication which cause hyperkalemia as a side effect.
The regime naturally includes other measures for treatment of major illnesses such as diabetes or renal diseases which have caused hyperkalemia.