A 52-year-old man with long-standing alcohol-related liver disease is brought to the Emergency Department after collapsing outside a shop.
Routine blood tests show:

Total calcium: 1.62 mmol/L
Albumin: 33 g/L

What is the most appropriate action regarding his calcium abnormality?

A. Rapid IV bolus of calcium chloride
B. Infusion of concentrated albumin
C. Rapid IV bolus of calcium gluconate
D. No immediate intervention
E. Slow infusion of calcium chloride

Table of Contents

Detailed Explanation

This patient has significant hypocalcaemia, which can be life-threatening. Because calcium binds to albumin, a low albumin level makes the measured calcium appear lower than the true “corrected” calcium.
However, after correction (for albumin), his calcium is still dangerously low (≈1.8 mmol/L), and given that he collapsed, he must be treated urgently.

Why calcium gluconate?

Calcium gluconate (10%, 10 mL over 10 minutes) is the safest and most commonly used IV form for emergency hypocalcaemia.
It is less damaging to veins than calcium chloride.
It effectively raises the ionised calcium quickly enough to prevent seizures, tetany, arrhythmias, or cardiac arrest.

Why not the other options?

Calcium chloride (fast bolus) → irritant to veins, risk of necrosis if extravasated; reserved for cardiac arrest or central-line administration.
Albumin infusion → corrects albumin, not acute ionised calcium; does nothing for urgent hypocalcaemia.
No action → unsafe; severe hypocalcaemia can cause collapse, seizures, or death.
Slow infusion of CaCl₂ → wrong preparation and too slow for an emergency.

Key clinical teaching

Emergency treatment of severe or symptomatic hypocalcaemia = 10 mL of 10% IV calcium gluconate over 10 minutes, with continuous ECG monitoring.

Cheat Sheet for Exams — Hypocalcaemia

Corrected calcium formula

Corrected Ca = Measured Ca + 0.02 × (40 − albumin)

Emergency indications

Tetany (carpopedal spasm)
Seizures
Stridor/laryngospasm
Prolonged QT
Arrhythmias
Syncope/collapse

Acute management

IV calcium gluconate 10% (10 mL over 10 minutes)
Repeat if symptoms persist
ECG monitoring
Then start slow infusion to maintain calcium levels
Always check magnesium (hypomagnesaemia causes refractory hypocalcaemia)

Causes of hypocalcaemia

Vitamin D deficiency
CKD
Post-thyroid/parathyroid surgery (hypoparathyroidism)
Pseudohypoparathyroidism
Acute pancreatitis
Massive blood transfusion (citrate binds Ca)
Rhabdomyolysis (early phase)
Magnesium deficiency
EDTA contamination (lab error)

Calcium preparations

Preparation	Notes
Calcium gluconate	Safest, preferred for IV replacement
Calcium chloride	More elemental calcium but irritant; central line preferred; for cardiac arrest

Flashcards

1. What is the first-line IV treatment for severe hypocalcaemia?
→ 10 mL of 10% calcium gluconate over 10 minutes.

2. Why is calcium gluconate preferred?
→ Less irritant to veins; safer for peripheral use.

3. What ECG finding is typical in hypocalcaemia?
→ Prolonged QT interval.

4. Name two severe symptoms of hypocalcaemia.
→ Tetany, seizures.

5. What must be monitored during IV calcium administration?
→ ECG (risk of arrhythmias).

6. List two common causes of hypocalcaemia.
→ CKD, vitamin D deficiency.

7. How does massive transfusion cause hypocalcaemia?
→ Citrate in blood products binds calcium.

8. How does hypomagnesaemia affect calcium levels?
→ Causes PTH resistance → refractory hypocalcaemia.

9. Is albumin infusion appropriate for acute hypocalcaemia?
→ No — it does not correct ionised calcium.

10. When is calcium chloride preferred?
→ Cardiac arrest, central venous access.

11. What is corrected Ca if albumin is low?
→ Measured Ca + 0.02 × (40 − albumin).

12. What electrolyte must be corrected if Ca fails to rise?
→ Magnesium.

13. What symptom can hypocalcaemia cause in nerves?
→ Paresthesias.

14. What respiratory issue can occur?
→ Laryngospasm.

15. Is a slow calcium infusion adequate in severe symptomatic cases?
→ No — rapid bolus required.

16. What lab error can falsely lower calcium?
→ EDTA contamination.

17. What endocrine cause leads to low Ca after surgery?
→ Hypoparathyroidism.

18. What is pseudohypoparathyroidism?
→ End-organ resistance to PTH.

19. How does pancreatitis cause low calcium?
→ Fat saponification → binds calcium.

20. What additional treatment is often required with vitamin D deficiency?
→ Vitamin D replacement.

MCQs (Covering All Key Points)

1. A patient has tetany and Ca 1.55 mmol/L. What is the immediate treatment?

A. Oral calcium supplements
B. IV calcium gluconate bolus
C. Albumin infusion
D. No treatment needed
Answer: B

2. Which electrolyte abnormality makes hypocalcaemia resistant to treatment?

A. Low sodium
B. Low potassium
C. Low magnesium
D. High phosphate
Answer: C

3. Which calcium preparation is safest through a peripheral line?

A. Calcium chloride
B. Calcium gluconate
C. Calcium carbonate
D. Calcium acetate
Answer: B

4. Which ECG change strongly suggests hypocalcaemia?

A. Peaked T waves
B. Short PR interval
C. Prolonged QT interval
D. ST elevation
Answer: C

5. Which of the following conditions typically causes hypocalcaemia?

A. Primary hyperparathyroidism
B. CKD
C. Thiazide diuretics
D. Sarcoidosis
Answer: B

Summary for Quick Revision

Hypocalcaemia becomes dangerous when ionised calcium falls enough to cause neuromuscular excitability, tetany, seizures, or arrhythmias. In the acute setting, the most important investigation is the corrected calcium, which adjusts for albumin levels. Severe hypocalcaemia must be treated immediately with 10 mL of 10% calcium gluconate over 10 minutes, with ECG monitoring. Calcium gluconate is preferred over calcium chloride because it is less irritant to veins and safer for peripheral administration. Calcium chloride contains more elemental calcium but risks tissue necrosis if extravasated, thus reserved for cardiac arrest or central-line delivery. Causes of hypocalcaemia include CKD, vitamin D deficiency, hypoparathyroidism, pseudohypoparathyroidism, acute pancreatitis, massive transfusion, rhabdomyolysis, and magnesium deficiency. Hypomagnesaemia is a key reversible contributor because it causes PTH resistance, making hypocalcaemia refractory to treatment. EDTA contamination of blood samples may give a falsely low reading and must be considered if results contradict clinical findings. Symptoms range from paresthesias to carpopedal spasm, bronchospasm, seizures, and prolonged QT leading to arrhythmias. After initial stabilisation, patients often require ongoing calcium infusions and correction of vitamin D or magnesium deficiency. Identifying the underlying cause is essential for long-term management.

Hypocalcemia