🚨 Severe Hypocalcaemia Management Summary ❓ Always ask: Are they on Digoxin?
📉 ECG monitoring and ensure the patient is in an appropriate environment (HDU/ICU if severe). 💉 If Ca²⁺ <1.9 mmol/L or symptomatic: Give 10–20 mL of 10% calcium gluconate IV over 20 min. 🫁 Stridor, seizures, tetany: Urgent ITU referral. 🔁 If symptoms persist: Infuse 100 mL of 10% calcium gluconate in 1 L 0.9% NaCl over 1–2 h. 💊 Step down: Switch to oral calcium + vitamin D once stabilised. ⚠️ Digoxin caution: Calcium can worsen toxicity - seek cardiology advice. 🧂 Always treat hypomagnesaemia if present. ⚡ Side effects of calcium gluconate: Hypotension, arrhythmias, thrombophlebitis, taste disturbance, flushing, nausea.

🚨 Severe Hypocalcaemia Management Summary
❓ Always ask: Are they on Digoxin?

📉 ECG monitoring and ensure the patient is in an appropriate environment (HDU/ICU if severe).
💉 If Ca²⁺ <1.9 mmol/L or symptomatic: Give 10–20 mL of 10% calcium gluconate IV over 20 min.
🫁 Stridor, seizures, tetany: Urgent ITU referral.
🔁 If symptoms persist: Infuse 100 mL of 10% calcium gluconate in 1 L 0.9% NaCl over 1–2 h.
💊 Step down: Switch to oral calcium + vitamin D once stabilised.
⚠️ Digoxin caution: Calcium can worsen toxicity - seek cardiology advice.
🧂 Always treat hypomagnesaemia if present.
⚡ Side effects of calcium gluconate: Hypotension, arrhythmias, thrombophlebitis, taste disturbance, flushing, nausea.

🔢 Calcium Levels (mg/dL → mmol/L multiply ×0.25)

Measurement	US Units (mg/dL)	UK Units (mmol/L)
✅ Normal	8.5 – 10.5	2.12 – 2.62
⬇️ Hypocalcaemia	< 8.5	< 2.12
⬆️ Hypercalcaemia	> 10.5	> 2.62

🧬 Aetiology & Pathophysiology

⬆️ Neuronal excitability → tetany, seizures, arrhythmias.
Due to membrane instability: cells depolarise more easily at low Ca²⁺.

📊 Causes of Hypocalcaemia

Cause	Clinical Features	Investigations	Management
Hypoparathyroidism	Tetany, seizures, perioral paraesthesia. +ve Chvostek & Trousseau.	Low Ca, low PTH, high phosphate.	Ca + vitamin D analogs ± recombinant PTH.
Vitamin D deficiency	Bone pain, muscle weakness, rickets/osteomalacia.	Low Ca, low Vit D, ↑PTH, low phosphate.	Vit D supplements ± Ca²⁺.
CKD	Bone pain, secondary hyperparathyroidism.	Low Ca, ↑PTH, ↑phosphate, ↓1,25-D.	Phosphate binders, active Vit D, Ca²⁺, treat CKD.
Hypomagnesaemia	Tetany, arrhythmias, refractory hypocalcaemia.	Low Mg, low/normal PTH, low Ca.	Mg replacement, then Ca correction.
Acute Pancreatitis	Abdo pain, vomiting, fat saponification.	Low Ca, ↑amylase/lipase.	Supportive care, Ca if severe.
Pseudohypoparathyroidism	Short stature, round face, skeletal defects.	Low Ca, high PTH, low phosphate.	Ca + Vit D analogs.
Sepsis	Shock, multi-organ failure.	Low Ca, evidence of infection.	Antibiotics + ICU support ± Ca.
Hungry Bone Syndrome	Post-parathyroidectomy, bone pain, hypophos.	Low Ca, low Mg, low phosphate.	Aggressive Ca + Vit D replacement.

⚡ Clinical Features

Acute: Tetany, paraesthesia, carpopedal spasm, stridor, seizures, prolonged QT.
Chronic: Poor dentition, brittle nails, basal ganglia calcification, cataracts, depression/psychosis.

🧪 Investigations

U&E, corrected Ca, Mg, phosphate, Vit D metabolites.
iPTH = key diagnostic test.
ECG: long QT ± arrhythmias.

📈 Interpretation Patterns

Low Ca + high PTH → CKD, Vit D deficiency, pseudohypoparathyroidism, hypomagnesaemia, sepsis.
Low Ca + low PTH → Hypoparathyroidism (post-op, autoimmune, congenital), severe Mg deficiency.

💊 Management

Mild (Ca 1.9–2.13 mmol/L): Oral Ca + Vit D (e.g., Sandocal, Adcal). Monitor weekly → 3–6 monthly.
Severe (<1.9 or tetany/seizures):
- ABC, airway secure if stridor/seizures.
- 10 mL 10% calcium gluconate IV in 100 mL saline/dextrose over 10–20 min (ECG monitor).
- If refractory → infusion: 100 mL 10% Ca gluconate in 1L saline at 50 mL/hr. Recheck Ca 4–6 hourly.
- Switch to oral once stable.
⚠️ Administer via large vein (avoid extravasation). Too rapid → flushing, hypotension, arrhythmias.
Digoxin users → avoid IV calcium unless life-threatening (risk of arrhythmia).
Consider CaCl₂ if central line in ICU (more irritant than gluconate).

📚 References

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Hypocalcaemia