Hyper and hypocalcaemia

Question 1

Define hypercalcaemia

Answer 1

Ca²⁺ >2.6 mmol/L

• Mild: 2.6-3.0 mmol/L
• Moderate: 3.0-3.4 mmol/L
• Severe: >3.4 mmol/L

Question 2

Give four causes of hypercalcaemia

Answer 2

• HyperPTH: typically mild asymptomatic
• Malignancy: suspect if rapid-onset; severe; or symptomatic
  
  • ​PTH-rp secretion (80%): paraneoplastic syndrome
  • Osteolysis (20%): breast cancer; myeloma
• Addison’s disease; thyrotoxicosis
• Acidosis
• Hyperalbuminaemia: pseudo-hypercalcaemia
• Excessive vitamin D
• Thiazide diuretics; lithium
• Sarcoidosis; TB
• Secondary hyperPTH in CKD

Question 3

State four presenting features of hypercalcaemia

Answer 3

Bones, stones, abdo groans, psych moans

• Bone pain
• Hypo- or areflexia
• Constipation; NaV; abdominal pain
• Generalised muscle weakness
• Confusion; hallucination; stupor
• Dehydration
• Renal stones

Question 4

List two ECG changes in hypercalcaemia

Answer 4

• Bradycardia
• AV block
• Short QT interval
• Osborn wave

Question 5

Request three investigations for hypercalcaemia/hypocalcaemia

Answer 5

• PTH
• TFTs
• U+Es
• Vitamin D
• Albumin
• PO₄^-; Mg²⁺
• CXR
• Light-chain assay

Question 6

Outline the treatment of hypercalcaemia

Answer 6

• Increase urinary excretion
  
  • Aggressive fluids
  • Loop diuretics
• Corticosteroids: decrease GI absorption
• Bisphosphonates; calcitonin

Question 7

Define hypocalcaemia

Answer 7

Serum Ca²⁺ <2.1 mmol/L

Question 8

Name four causes of hypocalcaemia

Answer 8

• Post-thyroidectomy
• Post-parathyroidectomy
• Severe vitamin D deficiency ^eg. dietary; cirrhosis; lack sunlight
• CKD
• Mg²⁺ deficiency: assists absorption of Ca²⁺
• Rhabdomyolysis; burns; tumour lysis syndrome
  
  • PO₄^- release binds to form insoluble [PO₄]²Ca₃
• Pancreatitis: insoluble calcium soaps
• Large volume blood transfusions: EDTA chelates with Ca²⁺
• Hypoalbuminaemia: pseudo-hypocalcaemia

Question 9

State four presenting features of hypocalcaemia

Answer 9

Calcium channels more excitable

Question 10

Describe the ECG findings of hypocalcaemia

Answer 10

• Prolonged QT interval
• Prolonged ST segment
• Arrhythmias:
  
  • Torsades de pointes
  • AF

Question 11

Outline the treatment of mild-moderate asymptomatic hypocalcaemia

Answer 11

‘Cause-specific’

• Vitamin D deficiency: Colecalciferol
• Post-thyroidectomy: Ca²⁺ supplements
• Hypomagnesaemia: IV Mg²⁺; stop preciptating drugs

Question 12

Outline the management of severe hypocalcaemia

Answer 12

Ca2+<1.9 or symptomatic is a medical emergency

• Contact senior
• Cardiac monitoring
• 10ml 10% calcium gluconate in 50ml 5% dextrose over 10min
• Repeat until asymptomatic, maximum four times (40ml/d)
  
  • ITU if no improvement and airway compromised
  • Calcium gluconate infusion if stable
  • Treat any reversible causes