N351 Electrolytes

Potassium, Sodium, Calcium, and Magnesium

Target Cells of Potassium (K⁺)

Cardiac cells

Etiology of Hypokalemia

• Excessive vomiting and diarrhea

• Potassium (K⁺) wasting diuretics

• Insulin administration → Drives K⁺ into cells, reducing serum levels

• Low dietary intake

Clinical Manifestations of Hypokalemia

• Muscle weakness or cramps

• Depressed T wave on ECG

• Cardiac dysrhythmias

Treatment of Hypokalemia

IV or PO potassium replacement

Nursing Considerations of Potassium (K⁺) Imbalances

Monitor:

• Continuous ECG

• Renal function

Replacement:

• K⁺ pills cannot be crushed

• IV K⁺ is given SLOWLY over several hours

  • Infiltration kills tissue around the IV site

  • Very caustic on peripheral veins

Safety:

• NEVER push IV K⁺ quickly

• Prefer central venous access over peripheral access

Etiology of Hyperkalemia

• Kidney failure → Unable to excrete K⁺

• Metabolic acidosis → H⁺ ions push K⁺ out of the cells and into the blood

• Crush injuries → Muscle cells break open and dump K⁺ into the blood

Clinical Manifestations of Hyperkalemia

• Flaccid paralysis

• Peaked T wave on ECG

• Cardiac dysrhythmias

Treatment of Hyperkalemia

• Insulin administration

• Loop diuretics

• Sodium polystyrene sulfonate (Kayexalate)

Normal Potassium Range

3.5 - 5 meEq/L

Target Cells of Sodium (Na⁺)

Brain cells

Etiology of Hyponatremia

• Excessive water intake

• Hypotonic IV solutions → Dilution of blood Na⁺

Clinical Manifestations of Hyponatremia

• Confusion

• Headache

• Seizures

Treatment of Hyponatremia

• Limit free water intake → Implement fluid restrictions

• Increase Na⁺ intake (salty foods/fluids)

• Isotonic IV fluids

• Hypertonic IV fluids (in severe cases)

Nursing Considerations of Sodium (Na⁺) Imbalances

Monitor:

• Level of consciousness (LOC)

• Input/outputs → Water follows Na⁺

Safety:

• Implement seizure precautions → Low bed, padded side rails, suction at bedside

IV Fluids:

• Hyponatremia = Hypertonic fluids in ICU

• Hypernatremia = Hypotonic fluids used cautiously due to cerebral edema

Etiology of Hypernatremia

• Lack of fluid intake

• Fluid loss from excessive vomiting or diarrhea

Clinical Manifestations of Hypernatremia

• Confusion

• Lethargy

• Seizures

Treatment of Hypernatremia

• Increase water intake

• Hypotonic IV fluids

*Oral intake is the primary mechanism; replace water deficit carefully

Normal Sodium Range

136 - 145 mEq/L

Target Cells of Calcium (Ca²⁺) and Magnesium (Mg²⁺)

Skeletal muscle cells, and some cardiac cells

Etiology of Hypocalcemia

• Hypoparathyroidism → Decreased ability to release parathyroid hormone (PTH) and absorb Ca²⁺ from food

• Vitamin D deficiency → Decreased ability to absorb Ca²⁺ from food

• Renal disease

Clinical Manifestations of Hypocalcemia

• Muscle cramps → High muscle excitability

• Paresthesia (pins and needles sensations)

• Positive Chvostek’s and Trousseau’s Sign

  • Chvostek = Cheek

  • Trousseau = Hand cramp

• Seizures (in rare instances)

Treatment of Hypocalcemia

• Increase dietary calcium and Vitamin D intake

• Calcium supplements

Nursing Considerations of Calcium (Ca²⁺) Imbalances

Monitor:

• Neuromuscular changes and muscle excitability

• Clinical response to electrolyte replacement

Safety: Implement seizure precautions if Ca²⁺ is very low

Replacement: If giving Ca^2+, check other medications for interactions

• e.g. tetracyclines

Etiology of Hypercalcemia

• Hyperparathyroidism → Increases parathyroid hormone levels and pushes Ca²⁺ out of the bones

• Some cancers → Cause bone breakdown

Clinical Manifestations of Hypercalcemia

• Skeletal muscle weakness → Decreased muscle excitability

• Nausea and vomiting (N/V)

• Constipation → Smooth muscles of the GI tract also lose excitability

Treatment of Hypercalcemia

• Decrease dietary calcium

• Phosphate supplements → Drives Ca²⁺ excretion

Normal Calcium Range

8.6 - 10.2 mg/dL

Etiology of Hypomagnesemia

• Low dietary intake

• Loop diuretics with high doses and long-term use

• Alcohol use disorder → The gut prioritizes removal of toxins over absorbing nutrients; causes damage to gut lining

Clinical Manifestations of Hypomagnesmia

• Cardiac dysrhythmias → Torsades de Pointes

• Hyperreflexia

Treatment of Hypomagnesemia

• Increase dietary intake

• Oral or IV magnesium supplements

Nursing Considerations of Magnesium (Mg²⁺) Imbalances

Monitor: Continuous ECG & Check reflexes

Safety: RR must be >12 to administer Mg²⁺

Replacement: IV Mg²⁺ can be very caustic to the vein

Etiology of Hypermagnesemia

• Renal failure

• Excessive magnesium replacement

Clinical Manifestations of Hypermagnesemia

• Slow cardiac dysrhythmias

• Decreased reflexes

• *Extreme highs can cause respiratory depression

Treatment of Hypermagnesemia

Stop magnesium containing medications

Normal Magnesium Range

1.5 - 2.4 mEq/L