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Calcium Imbalances

Calcium (8.5–10.5 mg/dL)

  • 99% of calcium is present in bones & teeth, 1% in blood and tissues
  • It is the most abundant mineral in the body,
  • It exists in two main forms in the blood:
      1. Ionized calcium – active form, essential for cell function – 4.5 to 5.6 mg/dL
      2. Bound calcium – attached to proteins, mainly albumin
  • Essential for Building bones & teeth, Nerve signal transmission, Muscle contraction and Blood clotting
  • Food Sources : Milk, cheese, yogurt, broccoli, soy milk, Tofu, Ragi (finger millet)
  • Regulators:
      1. Parathyroid Hormone (PTH) → raises blood calcium from bone resorption, kidney reabsorption, and by activating Vitamin D.
      2. Calcitonin → lowers blood calcium by inhibiting bone resorption and increasing renal excretion.
      3. Vitamin D (Calcitriol) → increases calcium absorption from intestine and supports bone mineralization.

 

Hypocalcemia (< 8.5 mg/dL)

Hypocalcemia refers to total Calcium < 8.5 mg/dL or ionized calcium < 4.5 mg/dL.

Causes

  • Thyroid or neck surgery → parathyroid damage , Hypoparathyroidism
  • Dietary Calcium or vitamin D deficiency
  • ESRD – Failure to convert vitamin D to its active form (calcitriol) 
  • Chronic diarrhea, Laxative abuse, Polyuria
  • Hyperphosphatemia →  Phosphate binds free calcium causing ↓ ionized Ca²⁺.
  • Hypomagnesemia → Low magnesium suppresses PTH secretion
  • Prolonged immobility.
  • Multiple blood transfusions →  Citrate in stored blood binds ionized calcium
  •  

Key Symptoms

  • Tetany (hallmark).
  • Chvostek’s sign – facial twitch when tapping nerve.
  • Trousseau’s sign – carpal spasm with BP cuff inflation.
  • Tingling (mouth/extremities), muscle cramps, seizures.
  • Laryngeal stridor (airway risk).
  • Prolonged QT on ECG → arrhythmia risk.
  • Danger Signs – Seizures, Laryngospasm, Ventricular tachycardia.

Management / Interventions

  1. Correct vitamin D deficiency, hypomagnesemia, hyperphosphatemia as advised
  2. After neck surgery, watch the patient closely for hypocalcemic symptoms.
  3. Implement seizure precautions – maintain a quiet, low-stimulation environment.
  4. Handle the patient gently to prevent pathological fractures due to bone fragility.
  5. Educate patient on the role of vitamin D in calcium absorption and dietary sources.
  6. Administer aluminum hydroxide to lower phosphorus, which increases calcium.
  7. Promote high-calcium diet and give vitamin D supplements for mild cases 
  8. Provide oral calcium carbonate if dietary intake is inadequate.
  9. Administer IV calcium for severe cases, slowly, with ECG monitoring.
  10. Keep emergency calcium gluconate (10%) readily available at the bedside 

 

Hypercalcemia (> 10.5 mg/dL)

Causes:

  • Hyperparathyroidism
  • Malignancy (bone metastases, multiple myeloma)
  • Prolonged immobilization
  • Vitamin D or calcium overdose
  • Thiazide diuretics

Pathophysiology 

  1. High calcium raises action potential threshold, slowing nerve conduction & causing muscle weakness, 
  2. Excess calcium precipitates in the kidneys, causing stones

Clinical Manifestations

  • Weakness, Reduced reflexes
  • Confusion, lethargy, coma (severe)
  • Cardiac Dysrhythmias, shortened QT interval
  • Polyuria, dehydration (excess calcium interferes with ADH action)
  • Renal calculi, flank pain(excess calcium precipitates in the kidneys)
  • Pathologic fractures (excessive bone resorption weakens bones)

Colloborative Nursing Management

  1. Administer Loop diuretics (furosemide) to promote calcium excretion.
  2. Avoid thiazide diuretics→  they increase calcium reabsorption in the kidneys
  3. IV isotonic saline to maintain hydration, prevent stones & increase urine output.
  4. Encourage weight-bearing exercises to strengthen bones & reduce calcium release.
  5. Administer prescribed medications such as bisphosphonates, calcitonin, or phosphorus supplements to lower calcium.
  6. Arrange dialysis if drug therapy fails or if the patient renal failure.
  7. Educate the patient to avoid high-calcium foods, maintain good hydration, and stay physically active to prevent further bone calcium loss.
  8. Handle the patient gently and assist with safe mobility to prevent fractures.
  9. Strain urine to detect and monitor kidney stone passage.
  10. Report: muscle weakness, confusion, severe constipation, flank pain
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