Abstract

The average potassium intake in the United States population ranges from 90 to 120 mEq/day. About 98% of the total body’s potassium is intracellular, and only 2% is present in the extracellular compartment. This distributional proportion is essential for cellular metabolic reactions and maintaining a gradient for resting membrane potential. A loss of this gradient results in hyper- or hypopolarization of the cell membrane, especially in cardiac muscles leading to life-threatening arrhythmias. Multiple mechanisms in human maintain homeostasis. Transient initial changes are due to transcellular shifts activating sodium-potassium ATPase pumps on the cell membrane. The kidneys essentially take part in excess potassium excretion, maintaining total body stores constant within normal range. Gastrointestinal secretion of potassium is insignificant in individuals with normal renal function, however plays an essential role in individuals with compromised renal function. So far, a classic feedback mechanism was thought to maintain potassium homeostasis; however, a recently recognized feedforward mechanism acting independently also helps preserve potassium homeostasis. Hence, potassium homeostasis is vital for humans to function at a normal level.

Highlights

  • The total body potassium (K+) in an average 70-kg adult is approximately 3000– 4000 mEq (50–55 mEq/kg) [1]

  • In patients with chronic renal insufficiency, especially when creatinine clearance is less than 10 mL/min, the net colonic K+ secretion increases compared to normal renal function due to increased expression and activity of the BK channel

  • An increase in dietary intake of K+ causes an increase in renal excretion of potassium, even though the K+ concentration is not sufficient to cause any changes in plasma K+ concentration or stimulate aldosterone

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Summary

Introduction

The total body potassium (K+) in an average 70-kg adult is approximately 3000– 4000 mEq (50–55 mEq/kg) [1]. Multiple physiologic processes have been identified in humans that maintain potassium homeostasis with a goal of appropriate tissue potassium distribution [1] They can be classified into two groups based on the mechanisms involved: transcellular shifts and potassium excess excretion. Transcellular mechanisms maintain the ICF (intracellular fluid): ECF (extracellular fluid) potassium ratio by acting immediately within the first few minutes to hours by regulating Na+/K+-ATPase (sodium/potassium adenosine triphosphatase pump), resulting in transcellular shifts. It is an electrogenic pump transporting sodium and potassium in the ratio of three sodium to two potassium. The delayed mechanisms are slower to kick in but play a significant role in the excretion of the excess potassium from the body via renal and gastrointestinal mechanisms

Insulin
Catecholamines
Exercise
Acid-base balance changes
Role of the colon in potassium homeostasis
Feedforward control of potassium balance
Circadian rhythm and potassium levels
Conclusion
Findings
Conflict of interest
Full Text
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