Hypercalcaemia
Background Information
Definition
Hypercalcaemia is defined as serum calcium >2.6 mmol/L
Classification of severity:
| Severity | Calcium concentration (mmol/L) |
|---|---|
| Mild | 2.6-2.9 |
| Moderate | 3.0-3.5 |
| Severe | >3.5 |
Aetiology
2 main causes: [Ref]
- Primary hyperparathyroidism – leading cause in outpatients
- Hypercalcaemia of malignancy – leading cause in hospitals
- From osteolytic lesions (common in cancer that metastasise to bone, e.g. breast cancer, prostate cancer, lung cancer), or
- From ectopic PTHrP secretion (common in squamous cell carcinoma, renal carcinoma)
Other causes: [Ref]
- Familial hypocalciuric hypercalcaemia
- Vitamin D-mediated hypercalcaemia
- Vitamin D intoxication
- Granulomatous disease (e.g. sarcoidosis, tuberculosis) (↑ 1 alpha-hydroxylase activity in macrophages)
- Lymphomas (↑ 1 alpha-hydroxylase activity)
- Medications
- Thiazide diuretic (reduces urinary calcium excretion)
- Lithium (increases PTH secretion)
- Calcium supplements
Clinical Features
Hypercalcaemia is usually only symptomatic in moderate to severe cases: [Ref]
- Renal stones: renal / ureteric stones, polyuria and polydipsia (from nephrogenic diabetes insipidus)
- Painful bones: bone / muscle / joint pain, pseudogout, muscle weakness
- Abdominal groans: abdominal pain, constipation, anorexia, N&V, pancreatitis
- Psychic moans: depression, fatigue, confusion
Management
Acute Management
Initial Management (ANY Causes)
Severe (>3.5 mmol/L) or symptomatic hypercalcaemia warrants acute management: [Ref1][Ref2]
- Most important and immediate management: IV fluid rehydration
- Typical initial fluid prescription: 1L of 0.9% saline over 4 hours
- Subsequent fluid: 200-500 mL/hr
- Calcitonin can be considered in life-threatening cases, and as a bridging therapy (NB it has a short half-life)
- Loop diuretics are reserved for fluid-overloaded patients, to be given after euvolaemia is achieved
Further Management
Further therapy is determined by the underlying cause: [Ref1][Ref2]
| Hypercalcaemia of malignancy | 1st line: IV bisphosphonates
Consider denosumab if refractory to bisphosphonates or if bisphosphonates are not appropriate |
| Vitamin D-mediated causes (e.g. vitamin D intoxication, granulomatous disease) |
|
If hypercalcaemia is refractory to medical therapy → dialysis
Long-Term Management
Long-term management depends on the underlying cause: [Ref1][Ref2]
- For primary hyperparathyroidism, see this article
- For hypercalcaemia of malignancy, bisphosphonates are the mainstay of management