How To Manage Hypocalcaemia

by

Dr Zaid Ismail

Introduction

Hypocalcaemia is a condition defined by a serum calcium level below the reference range (typically <2.2 mmol/L total calcium). It can present with neuromuscular, cardiac, and cognitive symptoms, requiring prompt recognition and management.

Causes of Hypocalcaemia

The most common causes include:

  • Vitamin D deficiency (e.g., due to malabsorption, chronic kidney disease, or inadequate intake)
  • Hypoparathyroidism (post-surgical, autoimmune, or genetic)
  • Chronic kidney disease (reduced activation of vitamin D and hyperphosphataemia)
  • Hypomagnesaemia (which impairs PTH secretion and function)
  • Acute pancreatitis (due to calcium sequestration)
  • Critical illness (e.g., sepsis, burns, tumour lysis syndrome)

Clinical Features

  • Neuromuscular symptoms: Tetany, paraesthesia (especially perioral and in hands/feet), muscle cramps, carpopedal spasm (Trousseau’s sign), and Chvostek’s sign (facial muscle twitching on tapping the facial nerve)
  • Cardiac manifestations: Prolonged QT interval, arrhythmias
  • Cognitive symptoms: Confusion, irritability, depression
  • Severe cases: Laryngospasm, seizures

Investigations in Primary Care

If hypocalcaemia is suspected, order the following:

  1. Serum calcium (corrected for albumin)
  2. Parathyroid hormone (PTH)
  3. Vitamin D (25-hydroxyvitamin D)
  4. Magnesium
  5. Renal function tests (U&Es, eGFR)
  6. Phosphate

Management

Mild Hypocalcaemia (Asymptomatic or Mild Symptoms, Calcium 2.0-2.2 mmol/L)

  • Not a medical emergency
  • Treat underlying cause (e.g., vitamin D deficiency, hypomagnesaemia)
  • Oral calcium supplements: Calcium carbonate or calcium citrate (e.g., 1–2 g elemental calcium per day)
  • Vitamin D supplementation: If deficient, consider cholecalciferol (e.g., 20,000 IU weekly or 800-2,000 IU daily depending on severity)

Moderate Hypocalcaemia(1.8-2.0 mmol/L)

  • Possible medical emergency, considering discussing with medics
  • Presence of any symptoms or ECG changes is signficant

Severe Hypocalcaemia (Symptomatic or <2.0 mmol/L, or with ECG changes)

  • Likely a medical emergency – referral to secondary care/admission

Referral Criteria

  • Acute symptomatic hypocalcaemia
  • Suspected hypoparathyroidism requiring endocrinology input
  • Persistent hypocalcaemia despite supplementation
  • Underlying chronic kidney disease with ongoing abnormalities

Key Takeaways for GPs

  • Vitamin D deficiency is a common and treatable cause
  • Severe or symptomatic cases need urgent hospital referral
  • Monitor calcium levels after starting treatment to prevent hypercalcaemia

References

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