Clinical presentation

• Incidental asymptomatic hypocalcaemia on blood results (usual presentation).

• Neuromuscular irritability: myoclonic jerks, jitteriness, exaggerated startle responses, seizures.

• Apnoea, cyanosis, tachypnoea, vomiting, laryngospasm.

• Cardiac symptoms and signs: tachycardia, heart failure, prolonged QT interval on electrocardiogram (ECG), decreased contractility. Severe vitamin D deficiency may present with cardiomyopathy.

Definition

Total calcium <2.2 mmol/L/ionized calcium <1.2 mmol/L.

• Note: physiological hypocalcaemia occurs after birth as the transplacental calcium supply is cut, there is insufficient supply from the GI tract and insufficient release of parathyroid hormone (PTH) from the immature parathyroid gland.

• Total calcium levels drop to about 2 mmol/L and ionized to about 1 mmol/L.

• The nadir in calcium level occurs within the first 48 h.

Approach to the problem

Hypocalcaemia is common, it is usually due to one of the following:

• Physiological, or an exaggeration of the normal physiological response.

• Iatrogenic and short lasting.

Other causes of hypocalcaemia are rare.

Aetiologies are conventionally grouped according to the time of onset:

• Early: within the first 4 days of life.

• Late: after 4 days of age.

History: Preterm, birth depression, infant of a diabetic mother, abnormality in maternal calcium metabolism.

Examination:

• Symptoms and signs of hypocalcaemia as above.

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