Calcium Abnormalities

Question 1

What is hypocalcaemia defined as?

Answer 1

• Serum corrected calcium concentration < 2.2 mmol/L
• Normal target = 2.2-2.6 mmol/L
• Mild → corrected Ca > 1.9 mmol/L
• Severe → correct Ca < 1.9 mmol/L

Question 2

Where is calcium found in our bodies?

Answer 2

Question 3

What are the causes of hypocalcaemia?

Answer 3

• With ↑PTH → Vit D def / CKD / Pseudohypoparathyroid / Rhabdo / Tumour lysis / Acute pancreatitis / Blood transfusion
• With ↓PTH → Neck surgery / Hypoparathyroid / DiGeorge Syndrome / Radiation
• Hypomagnesaemia (due to end-organ PTH resistance)
• Drugs → Bisphosphonates / Calcium chelators / Denosumab / Cinacalet

Question 4

What are clinical features of hypocalcaemia?

Answer 4

• Paraesthesia (peri-orally + fingers/toes)
• Muscle cramps
• Wheezing
• Laryngospasm
• CNS → seizures / irritability / confusion
• Chest pain
• Palpitations (arrhythmias)
• Trousseau’s and Chvostek’s sign

Question 5

It is important to distinguish whether the cause of hypocalcaemia is acute or chronic. Acute severe hypocalcaemia (< 1.9 mmol) is a medical emergency that requires urgent treatment and cardiac monitoring.

Which investigations help to determine underlying cause?

Answer 5

• Serum corrected calcium → < 2.2
• Bone profile
• U+Es
• Vit D
• PTH
• Mg
• ECG → prolonged QT

Other ix guided by presentation - eg lipase for suspected pancreatitis

Question 6

What is the management of mild hypocalcaemia (1.9-2.2 mmol/L)?

Answer 6

• Oral calcium supplements → Sandocal 2 tabs BD / Adcal D3 1-3 tabs BD
• Vit D replacement → weekly 6-8wks then daily
• Magnesium replacement (if ↓Mg)
  
  • IV Mg sulphate 2-5g in 100-250mls NaCl 0.9% / 1-4 hours
  • Oral Mg glycerophosphate 2 tablets TDS or Mg aspartate 6.5g sachet BD

Question 7

What is the management of severe hypocalcaemia (< 1.9 mmol/L or symptomatic at any level)?

Answer 7

• 10ml 10% IV calcium gluconate in 100mls of 0.9% sodium chloride or 5% dextrose over 10-20 mins - can be given neat over 3 mins if required
• Cardiac monitoring
• Consider repeat dose (until asymptomatic)
• Follow-up infusion → 100ml 10% calcium gluconate in 1L 0.9% NaCl or 5% dextrose given at rate of 50-100 ml/hr
• Calcium monitoring → check after 1-2 hrs of initial dose then monitor 4-6hrly
• Treat co-existent pathology (replace vit D or magnesium)

Question 8

What is hypercalcaemia defined as?

Answer 8

• Serum corrected calcium conc >2.6 mmol/L
• Mild → 2.6.3 mmol/L
• Moderate → 3.0-3.5 mmol/L
• Severe → >3.5 mmol/L

Question 9

What are the causes of hypercalcaemia?

Answer 9

• Malignancy → commonly due to release of PTHrP (mimics action of PTH); other mechanism is osteolytic damage to bone or activation of Vit D
• Hyperparathyroidism → elevated PTH 2^o to adenoma/hyperplasia
• XS Vitamin D → XS ingestion of Vit D or granulomatous disease inc Vit D activation
• Others → lithium / thiazides / adrenal insufficiency / familial

Question 10

What are the clinical features of hypercalcaemia?

Answer 10

“Bones, stones, abdo groans and psychic moans”

• Polyuria / polydipsia (mild) → Oliguria / Anuria (severe)
• Confusion / Coma
• Weakness / Fatigue / Dehydration (moderate)
• N+V / Abdo pain / Pancreatitis (severe)
• Cardiac dysrythmias (shortens QT)

Question 11

The diagnosis of hypercalcaemia is based on a serum corrected calcium > 2.6 mmol/L.

How can you confirm the hypercalcaemia?

Answer 11

Bone profile - level and duration

• Long-standing, asymptomatic mild hypercalcaemia may be seen in FHH
• Sudden, symptomatic, mod-severe hypercalcaemia suggestive of malignancy
• 1^o hyperparathyroidism usually seen w/ mild, chronic elevations in calcium

Question 12

What do PTH levels tell you about hypercalcaemia causes?

Answer 12

• Elevated PTH → primary or tertiary hyperparathyroidism
• Mid-upper normal PTH → inappropriately high + suggestive of hyperparathyroidism
• Low / normal → malignancy or hypervitaminosis D

Question 13

What common investigations should be done for hypercalcaemia?

Answer 13

• FBC / U+Es / LFT / CRP / ESR
• TFTs
• Vit D
• ACE (sarcoid)
• Malignancy screen + tumour markers
• Urine calcium levels (FHH)
• Imaging → CXR / CT CAP
• Parathyroid scans / Neck USS/MRI

Question 14

What is the treatment for mild (< 3 mmol/L) and asymptomatic/mild symptom hypercalcaemia?

Answer 14

• No specific treatment
• Increase oral fluids (6-8 glasses of water)
• Avoid precipitants eg. thiazide diuretics, lithium, dehydration

Question 15

What is the treatment for moderate (3-3.5 mmol/L) hypercalcaemia?

Answer 15

• Acute rise requires inpt admission for IV fluids
• Chronically raised may not require acute management
• Depends on aetiology and symptomatology

Question 16

What is the management for severe (>3.5 mmol/L) hypercalcaemia?

Answer 16

• Urgent admission to hospital
• Agressive IV fluids 200-300 ml / hr (4-6hrly bags)
• Then reduced to maintain UO at 100-150ml/hr (usually 8 hour bag enough)
• Can add loop diuretic to fluids
• Consider bisphosphonates (CI: renal impairment)

Corticosteroids for Vit D XS / Surgery for hyperparathyroid / Cinacalet / Dialysis