Popular Search hypertensionheart failurepneumothoraxhypohyperkalaemia

Hypocalcaemia

Table of Contents

Overview #

Key points

  • Often asymptomatic
  • Ensure you are looking at CORRECTED calcium (and IONISED calcium for severe hypocalcaemia).
  • Administer supplemental calcium through large peripheral vein, CVC or PICC line due to extravasation risk

Triage #

  • Symptomatic OR severe hypocalcaemia (corrected calcium ≤ 1.9 mmol/L or ionised calcium < 0.8mmol/L) – attend within 30 min
  • Asymptomatic OR mild hypocalcaemia (corrected calcium > 1.9 mmol/L) – can be handed over

Causes #

  • Hypocalcemia with low PTH [1] [2]
    • Destruction of parathyroid gland (auto-immune, post-op, irradiation)
    • Altered regulation of PTH
    • Functional hypoparathyroidism (hypomagnesemia or hypermagnesemia 
  • Hypocalcaemia with high PTH
    • Vitamin D deficiency/resistance (renal failure, rhabdomyolysis, tumour lysis)
    • Extravascular deposition (hyperphosphatemia, osteoblastic metastatic disease, pancreatitis) 
    • Large volume transfusions 
  • Other:
    • Medications – cytotoxics, PPIs, bisphosphonates, denosumab
    • Acute respiratory alkalosis 

Clinical features #

History [1]

  • Seizures
  • Lethargy
  • Myalgia or spasms
  • Paraesthesia- perioral, hands, feet
  • Tetany – involuntary muscle contractions

Examination

  • Chvostek sign – contraction of facial muscles on tapping of facial nerve anterior to tragus
  • Trousseau sign – spasm of hand when inflating BP cuff
  • Arrhythmias
  • Signs of heart failure
  • Hypotension 
  • Altered mental state

Diagnosis #

Based on serum calcium levels – note different tests for calcium [3]

  • Total calcium (2.10 – 2.60 mmol/L) – can be affected by serum albumin
  • Corrected calcium (2.10 – 2.60 mmol/L)  – corrected for albumin
  • Ionised calcium (1.16 – 1.30 mmol/L)

​​Corrected calcium (mmol/L) = total calcium (mmol/L) + 0.02 (40 – albumin [g/L])

Investigations #

Initial investigations [4]

InvestigationSignificance
CMPConcomitant Mg or PO4 changes
Calcium (ionised)Hypocalcaemia only significant clinically if ionised calcium is reduced [5]
AlbuminCan alter measured calcium levels
ECGHeart block, prolonged QT, Torsades

Further investigations to determine cause

InvestigationSignificance
Vitamin DCan have low vitamin D
PTHHypoparathyroidism
LipaseRule out pancreatitis
UECRenal failure
CK and urateRhabdomyolysis

Management – symptomatic OR ≤1.9 mmol/L corrected #

  1. DRSABCD (hypocalcaemia may cause laryngospasm)

+/- MET call if haemodynamically unstable (cardiac effects of hypocalcaemia)

+/- Code blue if airway compromise (laryngospasm, seizures)

  1. Consider acuity of hypocalcaemia 
  2. Escalate to senior clinician – consider escalation to ICU if refractory to initial management for faster replacement (such as intravenous replacement) and monitoring
  3. Initial correction of calcium levels [6] – to be guided by senior clinician

Rapid correction

Calcium gluconate 10% 10 mL (2.2 mmol elemental calcium) in Sodium chloride 0.9% 100 mL IV over 10 minutes

Maintenance infusion

Calcium gluconate 10% 50 mL (11 mmol elemental calcium) in Sodium chloride 0.9% 450 mL by IV infusion over 5-10 hours (rate 50 mL/hr)

Contraindications: digoxin toxicity

Safe for use in breastfeeding

No information on use of calcium gluconate during pregnancy – consult senior clinician

  1. Titrate supplemental calcium to maintain corrected serum total calcium concentration of 2.0 to 2.3 mmol/L
  2. Measure serum CMP every 4 hours
  3. Continuous cardiac monitoring during rapid IV infusion, or patients with cardiac arrhythmias or current digoxin therapy (should not delay administration) – NOT required if administering at < 2.2 mmol/hr in patients with normal ECG
  4. Monitor for signs of extravasation – discomfort, physical lump or redness at site. If present, cease infusion immediately and review (plastic surgical review if suspecting extravasation)
  5. If hypomagnesaemia (aim to achieve and maintain serum magnesium > 0.4 mmol/L) [7]

Symptomatic or clinical features present

Magnesium 25 to 50 mmol IV in Sodium chloride 0.9% 500 mL to 1000 mL over 12 to 24 hours


OR

Magnesium 10 mmol IV in Sodium chloride 0.9% 100 mL over 60 minutes

Asymptomatic, mild hypomagnesaemia

Magnesium aspartate 1000 to 3000 mg PO, daily in divided doses, with food

Once stable and able to tolerate oral intake

  1. Switch to oral calcium
Calcium carbonate 1.25 to 1.5 g PO BD with food ORCalcium citrate 2.38g PO BD
  1. If vitamin D deficient
Calcitriol 0.25 to 0.5 micrograms PO BD
  1. If hypomagnesaemia
Magnesium aspartate 1000 to 3000 mg PO, daily in divided doses, with food

Management – asymptomatic OR >1.9 mmol/L corrected #

  1. Treat underlying cause
  2. Oral calcium
Calcium carbonate 1.25 to 1.5 g PO BD with food ORCalcium citrate 2.38g PO BD
  1. Measures serum calcium and phosphate every 1-2 weeks
  2. If vitamin D deficient
Calcitriol 0.25 to 0.5 micrograms PO BD
  1. If hypomagnesaemia
Magnesium aspartate 1000 to 3000 mg PO, daily in divided doses, with food

References #

  1. Calcium – Hypocalcaemia [Internet]. Agency for Clinical Innovation. 2021 [cited 29 September 2021]. Available from: https://aci.health.nsw.gov.au/networks/eci/clinical/clinical-tools/electrolytes/calcium-hypocalcaemia 
  2. Hypocalcaemia [Internet]. Therapeutic Guidelines. 2019 [cited 29 September 2021]. Available from: http://tgldcdp.tg.org.au 
  3. Calcium [Internet]. The Royal College of Pathologists of Australasia. 2021 [cited 29 September 2021]. Available from: https://www.rcpa.edu.au/Manuals/RCPA-Manual/Pathology-Tests/C/Calcium 
  4. Nickson C. Hypocalcaemia [Internet]. Life in the Fast Lane. 2020 [cited 29 September 2021]. Available from: https://litfl.com/hypocalcaemia/ 
  5. Hypocalcaemia [Internet]. The Royal College of Pathologists of Australasia. 2021 [cited 29 September 2021]. Available from: https://www.rcpa.edu.au/Manuals/RCPA-Manual/Clinical-Problems/H/Hypocalcaemia 
  6. Fitzpatrick B. Calcium Gluconate (intravenous) – Medication Guideline. Melbourne: The Royal Melbourne Hospital; 2021.
  7. Hypomagnesaemia [Internet]. Therapeutic Guidelines. 2021 [cited 29 September 2021]. Available from: http://tgldcdp.tg.org.au 

  • Contributors

  • Reviewing Consultant/Senior Registrar

Dr Norine Ma

Dr Asha Bonney

What are your Feelings