Clinician Fact Sheet: Potassium and Iodine

October 2001; Volume 4; S1-S2

The Food and Drug Administration now permits foods that are high in potassium (350 mg/serving) and low in sodium, saturated fat, and cholesterol to include labeling claims that they might reduce the risk of stroke and the risk of developing high blood pressure.

Intake Recommendations

The normal adult daily requirement and usual dietary intake of potassium is 40-80 mEq.

Food Sources

Dietary sources of potassium include potatoes, bananas, cantaloupe, grapefruit, oranges, prunes, prune juice, tomato juice and paste, honeydew melon, molasses, bamboo shoots, chard, and cooked spinach.

Mechanism of Action

• Potassium plays a role in many body functions, including fluid balance, electrodynamic cell activity, isotonicity, and enzymatic reactions.

• Potassium also is involved in nerve impulse transmission; cardiac, smooth, and skeletal muscle contraction; renal function; tissue and carbohydrate synthesis; and gastric secretion.

Clinical Uses

• Orally, potassium is used to treat and prevent hypokalemia; to produce urinary alkalinization; to reduce blood pressure in people with hypertension; to reduce the risk of stroke; and to treat hypercalciuria.

• Intravenously, potassium is used to treat and prevent hypokalemia; arrhythmias, including atrial tachycardia and ventricular arrhythmias; and myocardial infarction.

Formulation and Dosage

• Potassium levels should be maintained between 3.5 and 5 mEq/L and should be monitored on an individual basis using serum potassium levels.

• To prevent hypokalemia: 20 mEq/d.

• To treat hypokalemia: 40-100 mEq/d in divided doses.

• To treat hypercalciuria: 1 mEq/kg/d.

• To treat hypertension: 48-90 mEq/d.

• To treat urinary alkalinization: 20-30 mEq qid of potassium citrate.

• Intravenous potassium products are available by prescription.

Adverse Effects/Toxicity

• Oral and intravenous potassium may cause stomach upset, nausea, diarrhea, vomiting, flatulence, ulcerations, and hyperkalemia. Large doses of potassium may cause paresthesias, generalized weakness, flaccid paralysis, listlessness, vertigo, mental confusion, hypotension, cardiac arrhythmias, heart block, and death.

Interactions/Nutrient Depletion

• Concomitant use of potassium with ACE inhibitors or potassium-sparing diuretics may increase potassium levels and the risk of hyperkalemia.

• Loop diuretics, thiazide diuretics, and stimulant laxatives increase potassium excretion and may cause hypokalemia.

• Bisacodyl may cause potassium loss in patients undergoing bowel-cleansing.

• In patients with renal dysfunction or using ACE inhibitors or potassium-sparing diuretics, potassium-containing foods and salt substitutes may increase potassium levels and and the risk of hyperkalemia.

• Potassium supplementation may increase serum and urine potassium concentrations and test results.

• Oral potassium may reduce blood pressure and blood pressure readings.

• Potassium is contraindicated in people with untreated Addison’s disease; heat cramps; acute dehydration; hyperkalemia; adynamia episodica hereditaria; severe renal impairment with oliguria, anuria, or azotemia; extensive tissue damage; or GI motility conditions.

• Potassium supplementation should be monitored closely in patients with heart and kidney disease, gastrointestinal bleeding disorders, and sickle cell anemia.

Iodine

Iodine deficiency is the most common cause of preventable mental retardation and brain damage.

Recommended Daily Allowance

Infants 0-6 mo: 110 mcg/d; 7-12 mo: 130 mcg/d. Children 1-8 y: 90 mcg/d; 9-13 y: 120 mcg/d. Men and women age 14 y and older: 150 mcg/d.

Food Sources

The most readily available dietary source of iodine is iodized salt.

Mechanism of Action

• Iodine kills microorganisms by oxidizing organic substrates.

• Iodine inhibits the release of thyroid hormone and also may increase respiratory secretions.

Clinical Uses

• Orally, iodine is used to treat thyroid storm, radiation emergency associated with radioactive iodides, cutaneous sporotrichosis, hyperthyroidism, endemic goiter, fibrocystic breast disease, and diabetic foot ulcers.

• Topically, iodine is used as an antiseptic.

Formulation and Dosage

• A 2% aqueous solution of iodine can be applied topically to affected skin.

• To prevent chemotherapy-induced mucositis, povidone iodine solution can be used as a mouth rinse several times daily.

• To treat fibrocystic breast disease, 0.08 mg/kg/d molecular iodine may be taken orally.

Adverse Effects/Toxicity

• Oral use of iodine may result in angioedema, cutaneous and mucosal hemorrhage, fever, arthralgia, lymph node enlargement, eosinophilia, urticaria, thrombotic thrombocytopenic purpura, and fatal periarteritis.

• Large doses and/or chronic use can cause metallic taste; soreness in teeth and gums; burning in mouth and throat; increased salivation; coryza; sneezing; eye irritation and swelling; headache; cough; pulmonary edema; swelling of parotid and submaxillary glands; inflammation of the pharynx, larynx, and tonsils; acne; gastric upset; diarrhea; anorexia; and depression.

• Prolonged use of iodides can cause thyroid gland hyperplasia, thyroid adenoma, goiter, and severe hypothyroidism.

Interactions/Nutrient Depletion

• Concomitant use of iodine with antithyroid drugs or lithium may result in additive hypothyroid activity and hypothyroidism.

• Concomitant use of iodine with potassium-containing products or ACE inhibitors may result in hyperkalemia.

• The di-iodotyrosine form of iodine can reduce thyroid volume in patients with goiter due to iodine deficiency.

• Potassium iodide can reduce serum thyroid hormone concentrations and test results.

• Chronic use or excessive amounts of iodides may cause or exacerbate thyroid gland hyperplasia, thyroid adenoma, goiter, and thyroidism.

Resources

International Council for the Control of Iodine Deficiency Disorders. Available at: www.tulane.edu/~idec/iddcomm.htm. Accessed September 19, 2001.

Natural Medicines Comprehensive Database [database online]. Stockton, CA: Therapeutic Research Center, Inc., 2000.

Pelton R, et al. Drug-Induced Nutrient Depletion Handbook. Hudson, OH: Lexi-Comp; 1999.

Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press; 2001.