Calcium (Hypo-Hypercalcaemia)

What is Hypocalcaemia?

Hypocalcaemia refers to an adjusted serum calcium level < 2.2 mmol/L. Severe hypocalcaemia is usually defined as < 1.9 mmol/L. It may cause neuromuscular irritability and cardiac instability, requiring urgent treatment if symptomatic or severe.

Common Causes

  • Vitamin D deficiency (dietary deficiency, limited sunlight, malabsorption)
  • Chronic kidney disease (impaired vitamin D activation and secondary hyperparathyroidism)
  • Hypoparathyroidism (post-thyroid/parathyroid surgery, autoimmune)
  • Magnesium deficiency (reduces PTH secretion and action)
  • Acute pancreatitis or rhabdomyolysis
  • Drugs: bisphosphonates, denosumab, phenytoin, cisplatin

Signs and Symptoms

  • Tingling or numbness around the mouth or fingers
  • Muscle cramps or spasms
  • Carpopedal spasm
  • Chvostek’s sign: facial twitching when tapping the cheek
  • Trousseau’s sign: hand spasm when inflating a blood pressure cuff
  • Fatigue, irritability, low mood
  • Severe cases: seizures, laryngospasm, prolonged QT interval

Primary Care Steps

  • Step 1: Confirm adjusted calcium and review albumin
  • Step 2: Assess for symptoms (tetany, seizures, breathing difficulty) and check ECG if concerns
  • Step 3: If asymptomatic and mild (2.0-2.2 mmol/L):
    • Repeat bloods within 1 week
    • Request PTH, vitamin D, magnesium, phosphate, urea and electrolytes
    • Try oral calcium supplementation (e.g. Adcal-D3 one tablet twice daily)
    • Treat vitamin D deficiency if present (e.g. colecalciferol loading regimen per local guideline)
  • Step 4: Recheck calcium in 1-2 weeks, then monitor periodically once stable
  • Step 5: Urgent same-day hospital referral if:
    • Calcium < 1.9 mmol/L
    • Any tetany, seizures, stridor, or ECG changes

Hospital Based Care (follow local guideline)

  • For calcium < 1.9 mmol/L or significant symptoms:
    • Give 10 ml calcium gluconate 10% diluted in 50-100 ml sodium chloride 0.9% over 10-20 minutes with cardiac monitoring
  • Assess response:
    • Repeat serum calcium 1-2 hours post-treatment
    • Repeat bolus if symptoms persist
  • If persistent hypocalcaemia:
    • Consider IV infusion: e.g. 100 ml calcium gluconate 10% in 1 litre sodium chloride 0.9% infused at a controlled rate
    • Monitor calcium every 4-6 hours
  • Correct magnesium deficiency before or alongside calcium replacement
  • Continuous ECG monitoring if severe
  • Investigate underlying cause
  • Involve endocrinology or nephrology if unclear cause or unstable levels

What is Hypercalcaemia?

Hypercalcaemia means the corrected (adjusted) calcium is high. It is usually defined as > 2.6 mmol/L.

  • Mild: 2.6-2.9 mmol/L
  • Moderate: 3.0-3.4 mmol/L
  • Severe: ≥ 3.5 mmol/L

It can cause dehydration, confusion, and heart rhythm problems, especially when calcium is very high or rising quickly.

Common Causes

  • Primary hyperparathyroidism (overactive parathyroid gland)
  • Cancer-related hypercalcaemia (e.g. myeloma, bone spread from cancer)
  • Dehydration (can push calcium up)
  • Medicines: thiazide diuretics, lithium
  • Too much vitamin D or calcium supplements
  • Granulomatous disease (e.g. sarcoidosis)
  • Long periods of immobility (especially in frailty)

Signs and Symptoms (simple guide)

  • Thirst, passing urine more often, dry mouth
  • Constipation, tummy pain, feeling sick
  • Tiredness, muscle weakness
  • Low mood or irritability
  • Confusion or drowsiness (more worrying)
  • Palpitations or chest discomfort (more worrying)

Stepwise Primary Care Approach

  • Step 1: Confirm the result
    • Check it is a corrected (adjusted) calcium
    • If borderline (e.g. 2.6-2.7), repeat within 1-2 weeks
  • Step 2: Quick safety check
    • Ask about confusion, severe weakness, vomiting, poor intake, palpitations
    • If unwell or very symptomatic, arrange same-day hospital assessment
  • Step 3: Look for a simple trigger
    • Check medicines: thiazides, lithium
    • Check supplements: calcium, vitamin D
    • Ask about dehydration (poor fluid intake, diarrhoea)
  • Step 4: Blood tests to find the cause
    • PTH (key test to split causes)
    • Urea and electrolytes (kidney function, hydration)
    • Vitamin D
    • Phosphate
    • ALP
  • Step 5: What to do while waiting
    • Stop calcium and vitamin D supplements unless a specialist has advised otherwise
    • Consider stopping a thiazide if safe and appropriate
    • Advise good oral hydration (unless fluid restriction)
    • Repeat calcium depending on level:
      • Mild and well: repeat in 1-2 weeks
      • Moderate and well: repeat within 48-72 hours (or same-day discussion with medical team)
  • Step 6: Referral triggers (simple rules)
    • Same-day hospital assessment: calcium ≥ 3.0 mmol/L with symptoms or any calcium ≥ 3.5 mmol/L
    • Urgent specialist referral: persistent calcium ≥ 3.0 mmol/L even if asymptomatic, or concern about cancer
    • Routine/endocrine referral: raised or inappropriately normal PTH (suggesting primary hyperparathyroidism), especially if persistent

Secondary Care Management (follow local guideline)

  • Main first step: IV fluids to correct dehydration and help the kidneys flush calcium
  • If cancer-related or severe/persistent: IV bisphosphonate to lower calcium (effect over 2-4 days)
  • Monitoring: U&Es and calcium monitored regularly, plus ECG if concerns
  • If not improving or kidney failure: specialist options such as calcitonin, denosumab (in selected cases), or dialysis
  • Cause is treated in parallel: e.g. myeloma work-up, imaging, endocrine input for parathyroid disease
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