Potassium

Overview

Potassium is one of the body’s three major electrolytes (the other two being sodium and chloride). They exist as fully dissociated ions and are the main particles responsible for osmotic pressure in body fluids. Potassium is the primary electrolyte functioning inside cells throughout the body. These substances are called electrolytes because they carry an electronic charge in their dissociated (ionic) state. Their ionic strength enables them to influence the solubility of proteins and other substances throughout the body.

Homostatic control of potassium and the other electrolytes is mediated through the hormones of the adrenal cortex and the anterior pituitary gland. Potassium is readily absorbed through the intestinal tract, and excess is efficiently excreted in the urine via the kidneys. The estimated safe and adequate intake of potassium for adults is from 1.8 to 5.6 grams daily.

Dosage Info

Dosage Range

Typically not more than 250mg to 2,000mg daily, which is approximately equal to 6mEq to 50 mEq of potassium. In cases of low blood levels of potassium, doses greater than 3,900mg (100mEq) per day have been used.

Most Common Dosage

Most healthy individuals get the required amounts of potassium from a healthy diet. Potassium supplementation is very specific, based upon low blood potassium levels and generally completed under medical supervision.

40mEq potassium
=~3.9g potassium acetate
=~4.0g potassium bicarbonate
=~3.0g potassium chloride
=~4.3g potassium citrate
=~9.4g potassium gluconate
=~5.4g potassium phosphate, monobasic
=~3.5g potassium phosphate, dibasic

Dosage Forms

Tablets, capsules, and injectables (Rx only).

Adult RDI

None established

Adult ODA

None established

RDA

• None established:

Interactions and Depletions

Depletions

• magnesium
• ascorbic acid
• albuterol
• Aminoglycosides
• amphotericin B
• Salicylates
• bisacodyl
• colchicine
• Corticosteroid medications
• foscarnet
• L-dopa
• Loop diuretics
• Calcium channel blockers
• Penicillins
• ritodrine
• sodium bicarbonate
• terbutaline
• Thiazide diuretics

Active Forms

Ascorbate, aspartate, carbonate, chloride, citrate, iodide, and phosphate.

Absorption

Potassium is efficiently absorbed from the gastrointestinal tract.

Toxicities & Precautions

General

In most individuals, excess potassium intake is either excreted or stored in the intestines as a reservoir for future use.

Functions in the Body

Acid/Base Balance

Potassium is one of the main electrolytes that helps control pH levels in body fluids.

Blood Pressure

In part regulated by potassium. Low potassium levels are associated with elevated blood pressure.

Electrical Activity

Potassium helps regulate electrical activity, which in turn, regulates the activity of muscle and nerve cells and the beating of the heart.

Glucose

Conversion to glycogen requires potassium.

Osmotic Pressure and Water Balance

Potassium is one of the electrolytes that control these functions through the activity of the sodium-potassium pump.

Clinical Applications

Cardiac Arrhythmias

Hypokalemia causes arrhythmias, which can be life threatening in cases of severe potassium depletion., (1)

Congestive Heart Failure

Patients with CHF who have low potassium because they are treated with medications, which deplete both potassium and magnesium, responded to supplementation. Low magnesium can further deplete potassium.

Kidney Stones

Potassium decreases urinary calcium excretion (2) and individuals with diets high in potassium have a lower risk of developing kidney stones. (3)

Hypertension

In patients with mildly elevated blood pressure, potassium can cause a significant reduction in both systolic and diastolic blood pressures. (4)

Symptoms and Causes of Deficiency

Excessive vomiting or diarrhea, kidney failure, diabetic acidosis, and prolonged malnutrition can cause potassium deficiency. Other factors that can contribute to potassium depletion include alcohol, caffeine, excessive use of salt or sugar and chronic stress. The symptoms associated with potassium deficiency include: irregular heartbeat, poor reflexes, muscle weakness, fatigue, continuous thirst, edema, constipation, dizziness, mental confusion, and nervous disorders.

Dietary Sources

Potassium is plentiful in the diet. Potassium-rich foods include fresh fruits and vegetables, peanuts, meat, and milk.

References

1. View Abstract: Maurat JP, et al. Cardiovascular pathology and magnesium. Therapie. Nov1993;48(6):599-607.
2. View Abstract: Lehman J, Jr. et al. Potassium Administration Increases and Potassium Deprivation Reduces Urinary Calcium Excretion in Healthy Adult. Kidney Int. 1991;39:973-83.
3. View Abstract: Curhan GC, et al. A Prospective Study of Dietary Calcium and Other Nutrients and the Risk of Symptomatic Kidney Stones. N Engl J Med. Mar1993;328(12):833-38.
4. View Abstract: Patki PS, et al. Efficacy of Potassium and Magnesium in Essential Hypertension: A Double-blind, Placebo Controlled, Crossover Study. BMJ. Sep1990;301(6751):521-23.