Calcium (Hypo-Hypercalcaemia)

What is Hypocalcaemia?

Hypocalcaemia refers to a corrected serum calcium level < 2.2 mmol/L. It may result in neuromuscular excitability and requires urgent treatment if symptomatic or severe.

Common Causes

  • Vitamin D deficiency (e.g. dietary, malabsorption)
  • Chronic kidney disease (secondary hyperparathyroidism)
  • Hypoparathyroidism (post-surgical, autoimmune)
  • Magnesium deficiency (impairs PTH secretion)
  • Acute pancreatitis or rhabdomyolysis
  • Drugs: bisphosphonates, phenytoin, cisplatin

Signs and Symptoms

  • Tingling or numbness around the mouth or hands
  • Muscle cramps or spasms
  • Shaky hands or stiff fingers
  • Chvostek’s sign: facial twitching when tapping the cheek
  • Trousseau’s sign: hand spasm when inflating a blood pressure cuff
  • Feeling tired, low mood, or irritable
  • Severe cases may cause seizures or difficulty breathing

Primary Care Steps

  • Step 1: confirm the low calcium result (adjusted for albumin)
  • Step 2: repeat the blood test in 1 week and order PTH, vitamin D, magnesium, and phosphate
  • Step 3: if mild (2.0–2.2 mmol/L) and no symptoms:
    • Begin oral calcium (e.g. Adcal-D3, one tablet twice daily)
    • Address any vitamin D shortfall
  • Step 4: repeat calcium weekly until stable, then monitor monthly
  • Step 5: refer to specialists if levels remain abnormal or symptoms develop

Hospital Based Care (follow local guideline)

  • For calcium < 1.9 mmol/L or significant symptoms:
    • Administer 10 ml calcium gluconate 10% diluted in 100 ml of saline or glucose over 10-20 minutes
    • In urgent cases, give undiluted slowly via IV over 3 minutes, with ECG monitoring
  • Assess response:
    • Check calcium 1-2 hours post-treatment
    • Repeat bolus if no improvement
    • Consider continuous infusion if unresolved
  • Infusion regimen:
    • Add 100 ml calcium gluconate 10% with 1L of fluid
    • Start infusion at 50 ml/hour and titrate as needed
    • Monitor calcium levels every 4-6 hours
  • Ensure magnesium is corrected before calcium if low
  • Monitor cardiac rhythm and QT interval
  • Explore causes such as kidney disease, parathyroid dysfunction, or vitamin D issues
  • Involve endocrinology or nephrology if uncertain or unstable

What is Hypercalcaemia?

Hypercalcaemia is defined as a corrected serum calcium level > 2.6 mmol/L. It is considered moderate if > 3.0 mmol/L and severe if > 3.5 mmol/L. It can cause serious cardiac and neurological symptoms if untreated.

Common Causes

  • Primary hyperparathyroidism
  • Malignancy (e.g. PTHrP secretion, bone metastases, myeloma)
  • Thiazide diuretics
  • Vitamin D or calcium supplementation
  • Sarcoidosis and other granulomatous disease
  • Prolonged immobility (especially in elderly)

Stepwise Primary Care Approach

  • Step 1: confirm corrected calcium > 2.6 mmol/L (repeat if borderline)
  • Step 2: check recent medications, vitamin D/calcium use, and symptoms
  • Step 3: request PTH, phosphate, vitamin D, renal function, ALP
  • Step 4: if mildly elevated (< 3.0 mmol/L) and asymptomatic:
    • Stop contributing medications and supplements
    • Advise good oral hydration
    • Repeat calcium in 1-2 weeks
  • Step 5: refer to hospital if calcium > 3.0 mmol/L, symptomatic, or raised PTH

Secondary Care Management (follow local guideline)

  • Severe hypercalcaemia (> 3.5 mmol/L or symptomatic):
    • IV rehydration
    • IV bisphosphonates
    • Monitor U&Es, calcium every 24 hrs
  • Moderate (3.0-3.5 mmol/L):
    • IV fluids and assess for underlying cause
    • Consider bisphosphonate if symptoms or rising calcium
  • Further investigation: PTH, myeloma screen, vitamin D, chest X-ray (if sarcoidosis suspected)
  • Consider calcitonin or dialysis if resistant or renal failure present
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