Potassium is an essential mineral constituent of the human body and is the chief cation found within the intracellular fluid of all cells. Multiple salts of potassium exist and can be useful as a medication for a wide range of indications. Since potassium is an essential electrolyte usually sourced through our diet, any condition in which a patient is unable to maintain their dietary intake is an indication for exogenous replenishment of potassium. Hence, the recommendation is to include potassium is included in electrolyte replacement regimens and form a part of intravenous maintenance fluids in adult as well as pediatric patients or as routine prophylaxis following surgery.

The chief indication for potassium administration is potassium deficiency or hypokalemia, a condition in which the level of serum potassium falls below a critical range. Hypokalemia can occur due to multiple reasons, mainly inadequate intake of potassium such as in the condition of malnutrition, malabsorption, debilitation, prolonged parenteral nutrition without potassium or excessive losses of potassium such as vomiting, diarrhea, excessive drainage of gastrointestinal fluids, dialysis, renal diseases, diabetic ketoacidosis, hyperadrenalism, use of diuretics, corticosteroids and amphotericin B. Hyperactivity of adrenal cortex called as Cushing syndrome is an another important causes of hypokalemia. Metabolic alkalosis can also cause hypokalemia by shifting potassium from the extracellular to the intracellular compartment.

Other recommended indications for potassium salts include:

Hypertension: Adequate intake of potassium is a recommendation to prevent the development of hypertension. Prescribers also give potassium supplements to improve blood pressure control in patients with known hypertension.[1]

Arrhythmia: When cardiac glycoside toxicity occurs as a result of a loss of potassium or in certain tachyarrhythmias following cardiac surgery.  

Thallium toxicity: Used intravenously in a limited fashion.[2][3]

Hyperthyroidism: Potassium iodide is prescribed as an oral adjunctive medication in the immediate preoperative period for patients with hyperthyroidism undergoing thyroidectomy.[4] It is also useful as an adjunct treatment of patients critically ill with thyrotoxicosis crisis.

Radiation protection: Oral potassium iodide can help to protect the thyroid gland by blocking thyroidal uptake of radioactive iodine isotopes either from environmental hazards or during treatment with radiopharmaceuticals.[5]

Sporotrichosis: Oral potassium iodide is considered the drug of choice for fixed cutaneous or lymphocutaneous sporotrichosis in resource-constrained countries because of its low cost.[6] However, there has been no comparison of its efficacy to antifungals such as itraconazole, and prolonged duration of therapy correlates with a high number of side effects.

Cough: Historically, clinicians have used potassium iodide to treat symptoms of chronic cough as an expectorant of tenacious mucus. However, its efficacy in this role is not well supported.

Alkalinization: Potassium citrate is useful to alkalinize urine in case of certain kinds of urinary tract calculi and management of conditions associated with chronic metabolic acidosis (chronic renal insufficiency and renal tubular acidosis). In these conditions, potassium citrate is used as an alternative to sodium citrate or sodium bicarbonate when a high amount of sodium administration is undesirable.

Antibiotics: Potassium is also used as a vehicle or compounding chemical for some antibiotic preparations (e.g., potassium benzylpenicillin, potassium penicillin V and amoxicillin-clavulanate potassium).

In its role as a major intracellular cation, potassium acts to preserve acid-base balance and maintenance of isotonicity as well as electrodynamic cellular function. It activates many enzymatic reactions within our body, and plays an essential role in the transmission of nerve impulses, contraction of cardiac muscles as well as skeletal and smooth muscles, tissue synthesis, gastric secretion, and renal function. Potassium reduces mean systolic and diastolic blood pressure.[1]

Potassium administration can be in the form of multiple salts, some of which can be ingested by the oral route (potassium chloride, acetate, bicarbonate, gluconate, and citrate) and some of which are given intravenously (potassium chloride and acetate). Certain potassium-containing compounds (e.g., potassium chloride) can be injected subcutaneously (hypodermoclysis).[7] The oral route is always preferable to intravenous injection except in critical hypokalemia; this is because the relatively slow process of gastrointestinal absorption of potassium salts limits the likelihood of a sudden, large increase in serum potassium concentration.

Oral Administration

Oral potassium supplements should be administered with or after meals to reduce gastrointestinal irritation and cathartic effect.

Oral potassium salts are usually administered in 1 to 4 doses daily. With a relatively high daily dosage (greater than 20 mEq), administration should be as divided doses.

Extended-release potassium chloride preparations are useful for patients who cannot tolerate or are non-compliant with multiple daily doses of potassium preparations. 

IV Infusion

Administration of potassium-containing infusions must be by slow intravenous infusion, including boluses of potassium for hypokalemia (rate of administration generally should not exceed 20 mEq/hour). When including potassium in long term or maintenance fluid administration, concentration should not exceed 40mEq/L (exceptions may be severe hypokalemia associated with cardiac arrhythmias or in diabetic ketoacidosis where higher concentrations of 60 to 80 mEq/L require caution). Continuous ECG monitoring and serial measurements of plasma potassium concentrations are essential during IV administration of potassium, particularly when the rate of administration is greater than 20 mEq/hour.

Potassium IV solutions should be administered only in patients who are well-hydrated and with adequate urine flow (especially in post-surgical patients).

The selection of potassium dosages requires caution in patients with renal impairment and geriatric patients.[8]

Potassium acetate, potassium chloride, and potassium phosphate are available as concentrated solutions that require dilution before intravenous administration. Local vascular intolerance may be a limiting factor in the ability to administer concentrated solutions. Ideally, potassium infusion administration should be via a large, high-flow vein (e.g., femoral vein), or administration of solutions of lower concentration may be in divided doses via peripheral veins. 

Dosage

The calculated dosage of potassium supplements is usually as mEq of potassium. Depending on the potassium supplement in use, the amount of oral supplement that will provide a particular dosage of potassium in mEq will vary. 

Normal adult daily potassium requirement and usual dietary intake of potassium is 40 to 80 mEq; infants and children require 2 to 3 mEq/kg or 40 mEq/m daily.

Hyperkalemia is the most common and life-threatening adverse effect of potassium administration and can develop rapidly.[9] This condition can manifest as potentially fatal bradycardia, asystole, and ventricular fibrillation.  

Gastrointestinal side effects commonly occur with enteral preparations, such as nausea, emesis, diarrhea, and abdominal pain.

Extravasation, local irritation, and phlebitis may occur due to improper dilution of intravenous preparations or administration through a peripheral vein.

Hypersensitivity reactions occur from the use of potassium iodide as well as chronic iodine poisoning (iodism).

Hyperkalemia is an absolute contraindication for potassium replacement. Inadequate or absent urine output and severe renal impairment are relative contraindications. Systemic acidosis and states of dehydration require correction before potassium administration. Potassium administration requires caution in states of significant tissue breakdown (e.g., burns or post-operative conditions), adrenal insufficiency, and with concomitant administration of potassium-sparing diuretics. Oral forms of potassium supplements should be used cautiously in patients who have delayed gastrointestinal transit due to structural or functional causes.

Potassium iodide is not for use in patients with known sensitivity to iodides.