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Calcium Imbalances

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References:

  1. Saunders Comprehensive Review for the NCLEX-RN Examination, 9th Edition, ISBN 978-032-37-9530-2, by Linda Anne Silvestri, Angela E. Silvestri, and Jessica Grimm (Ch. 8, pp. 88-105)

Hypocalcemia

Normal Serum Calcium Level: 9 to 10.5 mg/dL (2.25 to 2.75 mmol/L)

Hypocalcemia is a serum calcium level lower than 9.0 mg/dL (2.25 mmol/L). Its causes include:

  1. Inhibition of calcium absorption from the gastrointestinal tract: inadequate calcium intake, lactose intolerance (lactose enhances calcium absorption[citation needed]), malabsorption syndromes e.g. celiac sprue or Crohn’s disease, inadequate vitamin D intake, and end-stage kidney disease.
  2. Increased calcium excretion: kidney disease (polyuric phase), diarrhea, steatorrhea, and wound drainage (especially gastrointestinal).
  3. Conditions that decrease the ionized fraction of calcium: hyperproteinemia, alkalosis, medications (calcium chelators or binders), acute pancreatitis, hyperphosphatemia, and removal or destruction of the parathyroid glands.

Assessment

  1. Cardiovascular:
    • Decreased heart rate
    • Hypotension
    • Diminished peripheral pulses
  2. Respiratory: not directly affected, but failure or arrest may occur from muscle tetany or seizures affecting the respiratory muscles.
  3. Neuromuscular:
    • Anxiety; irritability
    • Irritable skeletal muscles: twitches, cramps, tetanus, seizures; hyperactive deep tendon reflexes
    • Paresthesias followed by numbness that may affect the lips, nose, and ears in addition to the limbs
    • Chvostek’s Sign: contraction of facial muscles in response to a light tap over the facial nerve in front of the ear.
    • Trousseau’s Sign: a carpal spasm induced by inflating a blood pressure cuff above the systolic pressure for a few minutes.
  4. Renal: urinary output varies depending on the cause
  5. Gastrointestinal: increased gastric motility; hyperactive bowel sounds; cramping, diarrhea
  6. Laboratory Findings: serum calcium level less than 9.0 mg/dL (2.25 mmol/L); ECG changes: prolonged ST and QT intervals

Interventions

  • Check albumin levels. Calcium binds to proteins, most prominently to albumin. A low albumin level may result in a reading of low serum calcium levels, despite no changes in total ionized calcium. If the client has a low albumin level, the calcium level should be corrected. It is determined through the formula . Alternatively, the ionized calcium level can be checked, which has a normal value of 4.64 to 5.28 in adults.
  • Administer calcium supplements orally or intravenously. When administering calcium intravenously, warm the injection solution to body temperature before administration. Administer slowly; monitor for ECG changes, infiltration, and hypercalcemia.
  • Administer medications that supplement calcium absorption.
    • Aluminum hydroxide reduces phosphorus levels, causing the countereffect of increasing calcium levels.
    • Vitamin D aids in the absorption of calcium from the intestinal tract.
  • Provide a quiet environment to reduce environmental stimuli.
  • Initiate seizure precautions.
  • Move the client carefully, and monitor for signs of pathologic fractures.
  • Keep 10% calcium gluconate available for treatment of acute calcium deficit.
  • Instruct the client to eat foods high in calcium: dairy products (milk, cheese, yogurt); tofu; green leafy vegetables (broccoli, collards, kale, mustard greens, turnip greens, bok choy); salmon and sardines; almonds, brazil nuts, sunflower seeds, tahini, and dried beans; blackstrap molasses.

Hypercalcemia

A serum calcium concentration that exceeds 10.5 mg/dL (2.75 mmol/L). Its causes include:

  1. Increased calcium absorption: excessive oral intake of calcium and/or vitamin D
  2. Decreased calcium excretion: kidney disease, the use of thiazide diuretics
  3. Increased bone resorption of calcium: hyperparathyroidism, hyperthyroidism, malignancy (bone destruction from metastatic tumors), and immobility
  4. Hemoconcentration: dehydration, lithium therapy, and adrenal insufficiency

Assessment

  1. Cardiovascular:
    • Increased heart rate in the early phase; bradycardia to cardiac arrest in late phases
    • Hypertension; bounding peripheral pulses
  2. Respiratory: ineffective respiratory movements as a result of profound skeletal muscle weakness.
  3. Neuromuscular:
    • Disorientation, lethargy, coma
    • Profound muscle weakness; diminished or absent deep tendon reflexes
  4. Renal: urinary output varies depending on the cause
  5. Gastrointestinal:
    • Decreased motility and hypoactive bowel sounds; constipation
    • Anorexia, nausea, abdominal distention
  6. Laboratory Findings:
    • A serum calcium level greater than 10.5 mg/dL (2.75 mmol/L)
    • Shortened ST and QT intervals; widened T wave; heart block

Interventions

Pathologic fractures are a risk for clients with calcium imbalances. Move them slowly and assist with ambulation.

  • Administer isotonic saline solutions are prescribed. Discontinue IV infusions of solutions containing calcium and oral medications containing calcium or vitamin D
  • Thiazide diuretics may be discontinued and replaced with diuretics that enhance the excretion of calcium
  • Administer medications as prescribed that inhibit calcium resorption from the bone e.g. phosphorus, calcitonin, bisphosphonates, and prostaglandin synthesis inhibitors (acetylsalicylic acid, nonsteroidal antiinflamatory medications)
  • If severe, prepare for dialysis if it does not respond to treatment.
  • Move the client carefully and monitor for signs of pathologic fracture
  • Monitor for flank or abdominal pain, and strain the urine to check for the presence of urinary stones.
  • Avoid foods high in calcium: dairy products (milk, yogurt, cheese); tofu; green leafy vegetables (broccoli, collards, kale, mustard greens, turnip greens, bok choy); salmon and sardines; almonds, brazil nuts, sunflower seeds, tahini, and dried beans; blackstrap molasses

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