Fluid and Electrolyte Review Part 1: Sodium, Chloride, and Potassium (NCLEX-style Flashcards)

A set of Q&A flashcards covering key concepts about sodium, chloride, and potassium, including normal ranges, clinical states (hypernatremia, hyponatremia, hyperchloremia, hypochloremia, hyperkalemia, hypokalemia), signs and symptoms, assessment considerations, and treatment strategies.

What is the most abundant extracellular cation and its primary job?

Sodium; regulates water balance; water follows sodium; important for nerves, brain, and muscles.

What is the normal extracellular sodium range in the body?

135–145 mEq/L.

What is hyponatremia?

Serum sodium less than 135 mEq/L.

What is hypernatremia?

Serum sodium greater than 145 mEq/L.

Name the three volemic states used to classify hypernatremia.

Euvolemic hypernatremia, hypovolemic hypernatremia, and hypervolemic hypernatremia.

Describe euvolemic hypernatremia.

Decreased body water with normal total body volume; sodium becomes concentrated; causes include diabetes insipidus or insensible water losses.

Describe hypovolemic hypernatremia.

Significant water loss with dehydration; reduced intravascular volume; examples include vomiting, diuretics, burns.

Describe hypervolemic hypernatremia.

Both sodium and water are increased; often from excess IV fluids or conditions causing sodium and water retention (e.g., aldosterone excess).

What mnemonic helps remember the causes of hypernatremia?

MODELS: Medications; Osmotic diuretics; Diabetes insipidus; Excessive water loss; Low water intake; Salt (sodium) intake.

What are the memory-aid signs of hypernatremia (fried and salted)?

Fried: fever, restlessness/agitation, increased fluid retention, edema, dry mouth. SALTED: flushed skin, altered level of consciousness, low urine output, thirst.

Which system findings help determine the cause of hypernatremia?

Neurologic status (level of consciousness) and cardiovascular volume status (euvolemic, hypovolemic, hypervolemic).

What is the treatment for euvolemic hypernatremia?

Provide free water (oral preferred); IV fluids are not ideal; correct slowly.

What is the treatment for hypovolemic hypernatremia?

Restore volume with IV fluids (usually normal saline) to dilute sodium, then provide free water to normalize levels; correct slowly.

What is the treatment for hypervolemic hypernatremia?

Discontinue causative agents; use loop diuretics to remove excess fluid; replace with free water to dilute sodium; avoid adding more fluids; correct slowly.

Why must sodium levels be corrected slowly in hypernatremia?

To prevent rapid shifts that cause cerebral edema and potentially seizures.

What does the management mnemonic 'LAG' relate to in hypernatremia?

L - Free water administration; A - Remove the causative agent; G - Give fluids (adjusted by euvolemic vs hypovolemic); aim for slow correction.

How should you approach sodium-related NCLEX-style questions that include numbers?

Ignore the raw number; compare to 135–145 normal range; determine clinical signs to identify hypernatremia or hyponatremia.

What is the normal chloride range?

96–108 mEq/L.

What is hyperchloremia and its common causes?

Chloride >108 mEq/L; causes include dehydration, vomiting, corticosteroid-induced retention of chloride, and excess chloride from IV fluids like normal saline.

What is hypochloremia and its typical causes?

Chloride <96 mEq/L; causes include volume retention/dilution or loss of salts (burns, vomiting, NG suction); treat underlying issue and address sodium as well.

What is the normal potassium range?

3.5–5.0 mEq/L.

Name the three major mechanisms of hyperkalemia.

(1) Potassium shifts from inside to outside cells due to cellular damage; (2) increased total potassium from intake or decreased excretion (e.g., renal failure); (3) medication effects (e.g., ACE inhibitors, potassium-sparing diuretics).

What is a hallmark EKG finding in hyperkalemia?

Tall, peaked T waves (also possible widened QRS, prolonged PR, flattened P waves).

List common signs/symptoms of hyperkalemia using the 'MURDER' mnemonic.

M: Muscle weakness/cramps; U: Urine abnormalities; R: Respiratory (shallow) due to diaphragm weakness; D: Decreased cardiac contractility; E: EKG changes (tall peaked T waves); R: Reflections (decreased reflexes).

What are first-line treatments to move potassium into cells in hyperkalemia?

Albuterol, bicarbonate, and IV insulin with dextrose (D5W).

What are ways to remove potassium from the body in hyperkalemia?

Potassium-wasting diuretics (furosemide), potassium-binding resins (kayexalate), dialysis; restrict potassium intake.

What is the role of calcium in hyperkalemia management?

Calcium (e.g., calcium gluconate) protects the myocardium and prevents arrhythmias but does not lower the potassium level.

Name some potassium-rich foods to avoid in hyperkalemia and foods to eat in hypokalemia.

Avoid: bananas, avocados, oranges, tomatoes, potatoes, spinach, dairy, beans, salmon. Eat more potassium-rich foods (in hypokalemia): bananas, avocados, oranges, potatoes, leafy greens, dairy, beans, meat, and certain fish.

How is hypokalemia typically treated?

Identify and treat the cause; avoid potassium-wasting meds if possible; give potassium via IV or oral supplements; consider dietary potassium; monitor closely (IV potassium should be given slowly, usually via a central line).