By Fidelindo Lim, DNP, CCRN
Clinical Assistant Professor
New York University College of Nursing
Among the many electrolytes, potassium takes celebrity status. It commands attention from most clinicians and it is perhaps the most prescribed electrolyte replacement after sodium chloride, followed by magnesium and phosphorous. In Cardiac Units, it is one of the staple drugs, the clinical twin of digoxin. Name brand orange juice products, bottled water and milk are now advertised as “potassium-rich” to lure not only the cardiac-compromised consumers but the general public. Potassium – it does the body good!
The Health Benefits of Potassium
When patients ask why we are giving them potassium, our standard reply is “it’s good for your heart.” But there is more to that. According to the National Council on Potassium in Clinical Practice (Cohn, Kowey, Whelton, & Prisant, 2000) there is evidence to support that high potassium diets may reduce the risk of stroke. As every nurse already know, sodium and potassium have an inverse relationship. Diets high in sodium will not only lead to hypertension, but it will also promote urinary excretion of potassium and therefore loose its health benefits. So, potassium can reduce stroke by lowering sodium levels and consequently maintaining normal blood pressure.
Studies also show that reduction in blood pressure after potassium supplementation is three times higher in African-Americans than in White Americans. This is not new. Caralis et al. (1984), suggests that when potassium level is below 3.5 mmol/L, potassium supplementation is essential even in asymptomatic patients with mild to moderate hypertension.
For patients with history of arrhythmia and myocardial infraction (MI), the threshold for potassium replacement is higher, at 4.0 mmol/L. The association between higher mortality from MI and ventricular fibrillation patients with potassium levels less than 3.9 mmol/L (normal range: 3.5 to 5.0 mmol/L has been known for some time (Duke, 1978). This knowledge becomes more important than ever based on the findings that currently, less than 2% of Americans consume the recommended minimum daily requirement for potassium, due primarily to inadequate plant food intake (NutritionFacts.org, n.d.).
Another important consideration is for patient’s taking digitalis. The effect of digitalis is enhanced in the presence of hypokalemia. Maintaining a normal potassium level is important in preventing digoxin toxicity and minimizing the potential adverse reactions of digitalis.
Pass the dried figs please…
Potassium should come from food sources. Fruits and vegetables are excellent sources of potassium. Its bicarbonate precursors, favorably affect acid-base metabolism, which may reduce risk of kidney stones and bone loss (Health.gov, 2008). Potassium-rich fruits and vegetables include leafy green vegetables, fruit from vines, and root vegetables. The recommended daily intake for potassium is as follows (Health.gov, 2008):
Recommended Daily Intake
Children 1 to 3 years of age
Children 4 to 8 years of age
Children 9 to 13 years of age
Adolescents and Adults
When teaching patients about dietary sources of potassium, most nurses stop short at bananas, although it contains average amounts of potassium compared with other food sources. One medium banana has approximately 422 mg of potassium; whereas one baked sweet potato has 694 mg (131 calories) (Health.gov, 2008). The New England Journal of Medicine published the following categories of excellent sources of dietary potassium:
Highest Content (>1000 mg [25 mmol] per gram)
Very High Content (>500 mg [12.5 mmol] per gram)
Dried Fruits (dates, prunes)
High Content (>250 mg [6.2 mmol] per gram)
Vegetables: Spinach, tomatoes, broccoli, winter squash, beets, carrots, cauliflower,
Fruits: bananas, cantaloupe, kiwi, oranges, mangos
Meats: ground beef, steak, pork, veal, lamb
Eight ounces of orange juice supplies approximately 450 mg of potassium. A glass of milk and a can of regular V-8 juice are also rich in potassium but unfortunately also loaded with sodium or sugar. The drawback of some of the potassium-rich food is cost and potential for weight gain (sweet potatoes with molasses, anyone?). In other words, for cardiovascular health, don’t limit yourself with bananas. Some people are even allergic to it or simply dislike its taste. For a list of excellent food sources of potassium check out the US Department of Agriculture Dietary Guidelines: http://www.health.gov/dietaryguidelines/dga2005/document/html/appendixB.htm#AppB1
In institutional settings, compliance with potassium therapy can be a challenge. Tablets are better tolerated than the liquid form for patients who can swallow. Compliance is also enhanced by the dosing schedule. The less frequent the patient takes the pill, the better the compliance. So, instead of giving 20 mEq BID, ask the doctor to order it as 40 mEq once a day as clinical condition allows. In patients taking diuretics, dietary consumption of potassium rich food is not enough and must be coupled with potassium supplement – an important teaching moment for patients and caregivers.
Making Potassium Easier to Swallow
Mixing potassium liquid with juice or ice makes it easier to swallow. To prevent the occlusion of feeding tubes (very annoying), give the liquid form instead of crushing the pills. Lastly, it is important to note that magnesium is an essential co-factor for potassium uptake and maintenance of intracellular potassium level. Therefore, potassium supplement works best when the magnesium level is within normal range (1.5 – 2.5 mEq/L). The clinically thinking nurse would be inclined to check the magnesium level when receiving orders to replace potassium.
Evidence from large, longitudinal studies, using worldwide sampling indicates that high-quality diets rich in potassium might achieve greater health benefits, including blood-pressure reduction (by extension a reduction in stroke and other cardiovascular events), than aggressive sodium reduction alone (Opari, 2014). Nurses are at the forefront of patient education. Discharge instructions and public health education using the teach-back method may help improve health literacy among high-risk populations.
African-Americans commonly have a relatively low intake of potassium and a high prevalence of elevated blood pressure and salt sensitivity, this population subgroup may especially benefit from an increased dietary intake of potassium (Health.gov, 2008).
Cohn, J., Kowey. P., Whelton, P., & Prisant, L. M. (2000). New guidelines for potassium replacement in clinical practice. Archive of Internal Medicine, 160(16), 2429-2436.
Caralis, P. V., Matterson, B. J., & Perez-Stable, E. (1984). Potassium and diuretic-induced ventricular arrhythmia in ambulatory hypertensive patients. Mineral Electrolyte Metabolism, 10 (3), 148-154.
Duke, M. (1978). Thiazide-induced hypokalemia: Association with acute myocardial infarction and ventricular fibrillation. JAMA, 239(1), 43-45.
Health.gov. (2008). Dietary Guidelines for Americans 2005. Retrieved from http://www.health.gov/dietaryguidelines/dga2005/document/html/appendixB.htm#AppB1
Oparil, S. (2014). Low sodium intake--cardiovascular health benefit or risk? New England Journal of Medicine, 371(7), 677-679. doi: 10.1056/NEJMe1407695.