Calcium - Hypocalcaemia

The classification of causes of hypocalcaemia:

  • hypoparathyroidism surgical (post-op) is the commonest cause, can also be auto-immune

  • hypomagnesaemia

  • vitamin D deficiency/resistance

  • renal failure, and renal losses (loopm diuretics)

  • drug related-cytotoxics, PPIs

  • metastatic disease e.g. osteoblastic secondaries (breast, prostate)

  • pancreatitis

  • rhabdomyolysis

  • large voume blood transfusions

Symptoms and Signs

  • Neurological: Seizures, lethargy, paraesthesia, tetany, respiratory arrest

  • Cardiovascular: Heart block, heart failure, ECG prolonged QT and rarely Torsades

  • Dermatological: Dry skin, brittle hair

  • Other: Cataracts, abdominal pain, diarrhea

  • Chvostek and Trousseau signs (see below)

Chvostek sign:

  • Tapping over the facial nerve anterior to the tragus causes contraction of the facial muscles

Trousseau sign:

  • Inflation of a BP cuff causes carpopedal spasm

Management

Mild – moderate (asymptomatic >1.9 mmol/L corrected):

  • Oral Calcium supplements

  • Find and treat the cause (in hospital setting is often post surgical)

  • Correct hypomagnesaemia

Severe (Symptomatic or ≤ 1.9 mmol/L corrected)

  • 10mLs 10% Calcium Gluconate in 5% Dextrose over 10mins, can be repeated.

  • Infusion is 100mLs of 10% calcium gluconate (ten vials) in one litre of Normal Saline or Dextrose 5% infused starting at 50-100mLs/hour, titrate to normocalcaemia.

  • Sampling for levels should be done at 2-6 hourly depending on degree and symptoms.

  • Calcium chloride can be used via a central line and will be run at reduced rates as it contains more 3 times more elemantal calcium, avoid use peripherally.

  • There appears to be no difference in rate of bio-availability. See ALiEM - Mythbuster Calcium Gluconate Raises Serum Calcium as Quickly as Calcium Chloride.

  • Find and treat the cause.

  • Correct hypomagnesaemia.

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