Potassium is essential for life. However, the National Kidney Foundation warns that this ubiquitous mineral can be too much of a good thing for patients with advanced kidney disease because when kidney function declines, kidneys are no longer able to effectively remove potassium from the blood. When this happens, blood levels--also known as serum levels--of potassium can become dangerously high.
Ranges
According to the National Kidney Foundation, safe levels of serum potassium fall between 3.5 and 5.0 milliEquivalents per liter. Levels between 5.1 and 6.0 are considered borderline high, and levels above 6.0 are considered dangerous. Dietary restriction of potassium may be advised if levels get too high.
Patients should consult their nephrologists before making any dietary changes. There is no benefit to potassium restriction if potassium levels are within a normal range.
Monitoring
The National Institute of Diabetes, Digestive and Kidney Disease explains that since since high potassium levels are associated with heart attack and irregular heartbeats, doctors monitor kidney patients' potassium levels through regular blood work. The frequency of this monitoring depends upon how much kidney function the patient has, how fast his function is declining and what type of kidney disease he has.
Potassium levels are reported on the patient's lab sheet under the letter "K"--the chemical abbreviation for potassium.
Process
In the body, potassium is found inside of nerve cells and outside of nerve cells in the serum. The difference between the concentration of potassium bound up in a nerve cell and the concentration of potassium outside of the cell is what enables the nerve cell to fire. High levels of potassium in the serum make it impossible for nerves to fire properly. The lack of normal nervous impulses gives rise to irregular heartbeats.
Guidelines
As dialysis provider DaVita notes, almost all foods have some potassium in them so portion control is critical. Eating too much of a low-potassium food can rapidly turn it into a high-potassium food.
The National Kidney Foundation provides a list of high-potassium foods that patients with high potassium levels should avoid. These include bananas, dried fruit, cantaloupe, kiwi, bran cereals, milk and chocolate. Yogurt, nuts and granola are also on the list of foods to choose with caution.
Patients who find it difficult to get sufficient nutrients on a renal diet should discuss this problem with their nephrologist, who may prescribe vitamin supplements specially tailored for renal patients.
Alternative
High-potassium foods can be converted into foods with lower levels of potassium. For example, the National Kidney Foundation recommends cutting potatoes, carrots and beets into small pieces and soaking them two hours in a volume of hot water that is 10 times larger than the volume of potatoes; for example, 1 cup of potatoes in 10 cups of water. Once the potatoes are removed from the water and rinsed, they should be boiled in five times the amount of freshly drawn water.
