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    Hypocalcemia

    Cardiovascular, Critical Care / Resuscitation, Gastrointestinal, Metabolic / Endocrine, Urological

    Last Reviewed on May 31, 2023
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    By Julian Marsden,Alexander Forrester

    First 5 Minutes

    Consider hypocalcemia for:

    • Seizures
    • Tetany
    • Laryngospasms
    • Coma
    • Torsades de Pointes

    Context

    Hypocalcemia is defined as [1]:

    • Corrected serum total calcium levels < 2.2 mmol/L
    • Ionized calcium 1.17 – 1.33 mmol/L
    • Corrected Ca = Measured Ca (mmol/L) + [40-(serum albumin g/L) x 0.02]

    New onset hypocalcemia may present to the ED as a life-threatening condition involving multiple organ systems [2].

    Common causes [1] [3] [4]:

    • Factitious (most common) e.g., low albumin, EDTA blood tube contamination, etc.
    • Post-surgical hypoparathyroidism
    • Poor dietary intake or malabsorption (Celiac, Crohn’s)
    • Vitamin D deficiency
    • Acute pancreatitis
    • Hyperphosphatasemia
    • Hypomagnesaemia
    • Hypoparathyroidism
    • Congenital / Inherited disorders (e.., DiGeorge syndrome)
    • Rhabdomyolysis
    • Critical Illness (e.g., sepsis)
    • Drugs
      • Diuretics
      • Beta-blockers
      • Phenytoin
      • Gentamicin
      • Heparin
      • Cimetidine
      • Ca channel blockers

    Most common manifestations of acute hypocalcemia are neuromuscular irritability [2]:

    • Paresthesia, numbness, tingling of perioral area, hands or feet
    • Carpopedal spasms
    • Seizures
    • Tetany
    • Laryngospasms (rare)

    Prolongation of the QT interval can cause cardiac arrythmias [1].

    • Torsades of pointes
    • Ventricular tachycardia/fibrillation

    Coma occurs in 2% of patients, and seizures in 8%. Laryngospasm is rare.

    In children 0-5 years old, hypocalcemia leads to potentially life-threatening complications (seizure, arrhythmia, and laryngospasm) in 6.1 per 100,000 patients.

    Diagnostic Process

    Clinical Hx [1] [5]:

    Laboratory Exams [1] [4] [6]:

    • Corrected serum calcium or ionized calcium
      • Normal serum corrected calcium 2.2 – 2.6 mmol/L.
      • Mild-moderate hypocalcaemia 1.9 – 2.2 mmol/L.
      • Severe hypocalcaemia < 1.9 mmol/L.
    • Serum phosphate & magnesium
      • Levels should be checked.
    • Parathyroid Hormone Levels (PTH)
      • If cause not immediately clear.
    • Glomerular Filtration Rate (GFR)
      • Renal failure may reduce resorption of calcium.
      • Associated with high serum phosphate.

    Figure 3. Simplified diagnostic process for new onset or acute hypocalcaemia [2] [1] [5] [4] [6]

    Recommended Treatment

    Goal of treatment is to raise serum calcium back to normal range [1] [3].

    • Treat the underlying cause of hypocalcemia.
    • Provide oral or IV Ca therapy.
    • Replace magnesium (any efforts to increase serum Ca while hypomagnesemic will not be effective due to magnesium effect on PTH production).
    • For suspected chronic, inherited, or other non-acute patients, refer to endocrinology and have followed by family physician.

    Mild or asymptomatic hypocalcemia treatment = ORAL calcium [4].

    • Indications:
      • Mild symptoms e.g., paresthesia
      • Asymptomatic
    • Administration:
      • Use calcium carbonate (40% elemental) or calcium citrate (21% elemental).
      • 1500 – 2000 mg elemental Ca per day, divided into 2-3 doses.
      • Vitamin D supplementation recommended to promote better Ca absorption.
      • In patients taking Proton Pump Inhibitor, don’t use calcium carbonate.

    Acute or severe hypocalcemia treatment = INTRAVENOUS Calcium [1] [3] [4]:

    • Indications:
      • Corrected serum Ca < 1.9 mmol/L or ionized Ca < 0.8 mmol/L.
      • Symptomatic hypocalcaemia.
      • Hyperkalemia – with cardiac complications (hypotension, dysrhythmias).
      • Hypermagnesemia.
      • Hypocalcemia with high inotrope requirement.
      • Ca channel blocker OD – please see CCB OD Summary.
      • Massive transfusion – as per MT protocol.
    • Administration:
      • Use central line if able and time allows.
      • 100 – 300 mg elemental Ca in 100 mL dextrose over 10 – 20 minutes[JM1] [AF2].
        • Calcium gluconate: 93 mg elemental Ca / 1g
        • Calcium chloride: 273 mg elemental Ca / 1g
      • Follow with continuous infusion 0.5-1.5 mg elemental Ca/kg per hour.
      • Periodically monitor blood Ca levels until symptoms resolve.
      • Monitor with EKG during IV Ca bolus.
      • Ca gluconate preferred, less likely to cause tissue necrosis in extravasation [7].
    • Contraindications [7]:
      • Hypercalcemia, hypersensitivity to calcium gluconate or calcium chloride
      • Sarcoidosis.
      • In neonates, do not administer with Ceftriaxone.
      • In older patients, flush IV lines between administration of Ca and Ceftriaxone.
      • Caution in patients with severe hypophosphatemia.

    Criteria For Hospital Admission

    Acute or severe hypocalcaemia.

    Criteria For Transfer To Another Facility

    Transfer will depend on local guideline and if acute presentation cannot be managed at the current facility.

    Criteria For Close Observation And/or Consult

    Confirmed acute or severe cases of hypocalcemia, or when the cause is not known, may be referred to proper specialty service for definitive diagnosis, work-up and treatment.

    • Endocrinology
    • Internal medicine

    Criteria For Safe Discharge Home

    • Hypocalcemia complications treated.
    • Underlying cause identified or treated.
    • Follow-up appointment with specialist or family physician booked (if required).

    Context

    Quality Of Evidence?

    Justification

    Due to variable nature of presentation, causes and treatments, quality of evidence considered low/moderate.

    Low-Moderate

    Related Information

    OTHER RELEVANT INFORMATION

    Reference List

    1. Burns & Buttner. ECG Library – Hypocalcaemia. Retrieved from Life in the Fastlane 2021. https://litfl.com/hypocalcaemia-ecg-library/


    2. Pepe et al. Diagnosis and Management of Hypocalcemia. Endocrine. 2020, 69(3), 485-495. doi:10.1007/s12020-020-02324-2


    3. Hypocalcaemia DDx. Retrieved from Life in the Fastlane 2023. https://litfl.com/hypocalcaemia-ddx/


    4. Goyal et al. Hypocalcemia. Retrieved from In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing 2022. https://www.ncbi.nlm.nih.gov/books/NBK430912/


    5. Hypocalcaemia. Retrieved from Life in the Fastlane 2020. https://litfl.com/hypocalcaemia/


    6. Pancreatitis. Retrieved from Life in the Fastlane 2020. https://litfl.com/pancreatitis-ccc/


    7. Chakraborty & Can. Calcium Gluconate. Retrieved from In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing 2022. https://www.ncbi.nlm.nih.gov/books/NBK557463/


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