Electrolytes NCLEX Cheat Sheet

As a nurse you are expected to know about electrolytes, their normal levels and what effect they have on the body if they fall outside of their usual range. Here are a few key electrolytes you’ll want to memorize!
Electrolyte Cheat Sheet

Electrolytes Study Review

Serum sodium


  • A major cation of extracellular fluid
  • Maintains osmotic pressure and acid-base balance, and assists in the transmission of nerve impulses
  • Is absorbed from the small intestine and excreted in the urine in amounts dependent on dietary intake
  • Minimum daily requirement of sodium is approximately 15 mEq.

Nursing consideration: Drawing blood samples in the extremity in which an intravenous (IV) solution of sodium chloride is infusing increases the level, producing an inaccurate result.

Serum potassium


  • A major intracellular cation, potassium regulates cellular water balance, electrical conduction in muscle cells, and acid-base balance.
  • The body obtains potassium through dietary ingestion and the kidneys preserve or excrete potassium, depending on cellular need.
  • Potassium levels are used to evaluate cardiac function, renal function, gastrointestinal function, and the need for IV replacement therapy.

Nursing considerations

  1. Note that the client is receiving potassium supplementation on the laboratory form.
  2. Clients with elevated WBC counts and platelet counts may have falsely elevated potassiumlevels.

Serum chloride


  • A hydrochloric acid salt that is the most abundant body anion in the extracellular fluid
  • Functions to counterbalance cations, such as sodium, and acts as a buffer during oxygen and carbon dioxide exchange in red blood cells (RBCs)
  • Aids in digestion and maintaining osmotic pressure and water balance

Nursing consideration:

Any condition accompanied by prolonged vomiting, diarrhea, or both will alter chloride levels.

Serum bicarbonate


  • Part of the bicarbonate-carbonic acid buffering system and mainly responsible for regulating the pH of body fluids

Nursing consideration: Ingestion of acidic or alkaline solutions may cause increased or decreased results, respectively.

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