What are the indications for referral to secondary care for a patient with hypercalcaemia?

Indications for referral to secondary care for a patient presenting with hypercalcaemia include:

• Severe hypercalcaemia (corrected calcium >3.5 mmol/L) or severe symptoms: arrange emergency hospital admission for specialist assessment and management such as intravenous fluids and bisphosphonate therapy ¹.
• Moderate hypercalcaemia (corrected calcium 3.0–3.5 mmol/L) or symptomatic patients: consider immediate same-day referral to hospital or liaise with an appropriate specialist depending on clinical picture ¹.
• Mild hypercalcaemia (corrected calcium >2.6 but <3.0 mmol/L) if asymptomatic but persistent after correction of reversible causes, or if primary hyperparathyroidism is suspected (e.g., raised PTH): refer to an endocrinologist for further investigation and management ¹.
• Known or suspected malignancy-associated hypercalcaemia: refer urgently via local cancer pathways or liaise with oncologist/palliative care specialist for management, especially if hypercalcaemia is moderate or severe ¹.
• Features suggestive of primary hyperparathyroidism requiring surgical consideration, including symptoms of hypercalcaemia, end-organ damage (renal stones, fragility fractures, osteoporosis), or albumin-adjusted serum calcium ≥2.85 mmol/L: refer to a surgeon with expertise in parathyroid surgery ².
• Unexplained hypercalcaemia after initial investigations in primary care: refer to an appropriate specialist (e.g., endocrinologist) for further assessment ¹.

Additional considerations: If the patient is on medications that may cause hypercalcaemia (e.g., thiazides, lithium), consider stopping and rechecking calcium before referral unless calcium remains elevated ¹. Liaise with mental health specialists if lithium is involved ¹.