Fluid & Electrolyte Imbalances: Nursing Assessment Guide

Sodium (Na+): Normal: 135-145 mEq/L

Hyponatremia (<135)

Causes: SIADH, heart failure, water intoxication, diuretics

Signs: Confusion, headache, nausea, seizures, muscle cramps

Nursing: Fluid restriction, monitor neuro status, hypertonic saline for severe cases

Hypernatremia (>145)

Causes: Dehydration, diabetes insipidus, excess sodium intake

Signs: Thirst, dry mucous membranes, restlessness, elevated temperature

Nursing: Administer hypotonic fluids (0.45% NS), monitor I&O

Potassium (K+): Normal: 3.5-5.0 mEq/L

Hypokalemia (<3.5)

Causes: Diuretics (furosemide), vomiting, NG suction, alkalosis

Signs: Muscle weakness, fatigue, leg cramps, dysrhythmias, decreased bowel sounds

ECG: Flattened T waves, U waves, ST depression

Nursing: KCl replacement (never IV push!), cardiac monitoring, assess dig levels

Hyperkalemia (>5.0)

Causes: Renal failure, ACE inhibitors, K+-sparing diuretics, acidosis

Signs: Muscle weakness, dysrhythmias, paresthesias, nausea

ECG: Tall peaked T waves, wide QRS, cardiac arrest risk

Nursing: Kayexalate, calcium gluconate (cardiac protection), insulin + glucose, dialysis

Calcium (Ca²+): Normal: 8.5-10.5 mg/dL

Hypocalcemia (<8.5)

Causes: Hypoparathyroidism, vitamin D deficiency, pancreatitis

Signs: Trousseau's sign (hand spasm with BP cuff), Chvostek's sign (facial twitch), tetany, seizures

Nursing: IV calcium gluconate, seizure precautions, cardiac monitoring

Hypercalcemia (>10.5)

Causes: Hyperparathyroidism, malignancy, immobilization

Signs: "Bones, stones, groans, moans": bone pain, kidney stones, GI symptoms, confusion

Nursing: Hydration with NS, loop diuretics, calcitonin, monitor cardiac rhythm

Magnesium (Mg²+): Normal: 1.5-2.5 mEq/L

Hypomagnesemia (<1.5)

Causes: Alcoholism, malnutrition, diuretics

Signs: Tremors, hyperreflexia, seizures, dysrhythmias

Nursing: Magnesium sulfate IV, seizure precautions

Hypermagnesemia (>2.5)

Causes: Renal failure, excess magnesium intake

Signs: Decreased reflexes, hypotension, respiratory depression, cardiac arrest

Nursing: Calcium gluconate (antidote), respiratory support, discontinue Mg sources

IV Fluid Types

Isotonic (Same osmolality as blood)

• 0.9% NS: Fluid resuscitation, blood transfusions
• Lactated Ringer's: Burns, surgical patients (NOT with blood products)
• D5W: Isotonic in bag, becomes hypotonic in body

Hypotonic (Lower osmolality)

• 0.45% NS: Cellular dehydration, hypernatremia
• Pulls fluid INTO cells: never give to patients with increased ICP

Hypertonic (Higher osmolality)

• 3% NS: Severe hyponatremia (administer via central line)
• D10W, D50W: Hypoglycemia
• Pulls fluid OUT of cells

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