Hypercalcaemia of Malignancy

📋 Key Information Summary

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Hypercalcaemia of malignancy (HCM) affects 20–30% of cancer patients and is the most common metabolic emergency in oncology.
Two principal mechanisms: humoral hypercalcaemia of malignancy (HHM) via PTHrP secretion and local osteolytic hypercalcaemia (LOH) from osteolytic metastases.
Always confirm corrected calcium with albumin; ionised calcium is the gold standard for acutely unwell patients.
Exclude primary hyperparathyroidism by checking PTH — PTH is suppressed in HCM (except rare co-secretion tumours).
Severity is graded: mild (2.60–2.99 mmol/L), moderate (3.00–3.49 mmol/L), severe (≥3.50 mmol/L), or hypercalcaemic crisis (≥3.50 with altered consciousness).
Aggressive IV 0.9% sodium chloride is the cornerstone of initial resuscitation — aim for 150–200 mL/hr after initial 1–2 L bolus.
Calcitonin (salmon calcitonin 4–8 IU/kg SC/IM q12h) provides rapid calcium lowering within 4–6 hours but has tachyphylaxis at 48 hours.
Zoledronic acid 4 mg IV over ≥15 min is first-line antiresorptive therapy; onset 2–4 days, nadir at 4–7 days.
Denosumab 120 mg SC is second-line for bisphosphonate-refractory HCM or when renal impairment precludes IV bisphosphonates.
Loop diuretics (frusemide) are NOT first-line and should only be used to manage fluid overload after adequate hydration.
Dialysis is reserved for refractory cases, renal failure, or hypercalcaemic crisis unresponsive to pharmacotherapy.
Definitive treatment requires addressing the underlying malignancy with systemic anti-cancer therapy.
Aboriginal and Torres Strait Islander patients may present later with higher calcium levels; culturally safe communication and access to specialist oncology services are essential.

Introduction & Australian Epidemiology

Hypercalcaemia of malignancy (HCM) is the most common life-threatening metabolic emergency encountered in oncology, accounting for approximately 30% of all hypercalcaemia presentations to Australian emergency departments. It reflects the complex interplay between tumour-derived humoral factors, osteolytic bone destruction, and impaired renal calcium excretion.

In Australia, HCM most commonly complicates squamous cell carcinomas of the head, neck, and lung (where PTHrP-mediated humoral hypercalcaemia predominates), breast carcinoma (where both humoral and osteolytic mechanisms operate), and multiple myeloma (predominantly osteolytic). Renal cell carcinoma and certain lymphomas are also important aetiologies.

Data from the Australian Institute of Health and Welfare (AIHW) indicate that cancer remains the leading cause of disease burden in Australia, with approximately 150,000 new diagnoses annually. Hypercalcaemia complicates the course of 10–20% of all cancers overall, rising to 20–30% in advanced metastatic disease. The development of HCM typically heralds advanced-stage malignancy and carries significant prognostic implications, with median survival of 1–3 months in many tumour types if the underlying malignancy cannot be controlled.

Early recognition and aggressive management are critical. Left untreated, severe hypercalcaemia (corrected calcium ≥3.50 mmol/L) progresses to renal failure, cardiac arrhythmias, coma, and death. The Australian Commission on Safety and Quality in Health Care (ACSQHC) recognises metabolic emergencies including HCM as requiring standardised escalation pathways in acute care settings.

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Clinical pearl: Hypercalcaemia is often diagnosed incidentally on routine bloods in patients with known malignancy. A corrected calcium ≥2.60 mmol/L in a cancer patient should prompt urgent assessment, even if asymptomatic. The severity of symptoms does not always correlate with calcium level.

Pathophysiology — HHM vs Local Osteolytic Hypercalcaemia

Understanding the dominant pathophysiological mechanism guides diagnostic workup and therapeutic targeting. Two principal mechanisms account for the majority of HCM cases, with a third (1,25-dihydroxyvitamin D-mediated) seen in certain lymphomas.

Humoral Hypercalcaemia of Malignancy (HHM)

HHM is the most common mechanism (accounting for ~80% of HCM cases) and is mediated by tumour secretion of parathyroid hormone-related peptide (PTHrP). PTHrP shares N-terminal homology with parathyroid hormone (PTH) and binds the PTH1 receptor, producing effects that mimic primary hyperparathyroidism:

Increased bone resorption: PTHrP stimulates osteoclastic activity, releasing calcium from the skeleton into the circulation.
Increased renal calcium reabsorption: PTHrP acts on the distal convoluted tubule to enhance calcium resorption, further raising serum calcium.
Decreased renal phosphate reabsorption: Leading to hypophosphataemia — a biochemical signature shared with primary hyperparathyroidism.
Suppressed PTH: Endogenous PTH is appropriately suppressed by the hypercalcaemia (unlike primary hyperparathyroidism).

HHM is classically associated with squamous cell carcinomas (lung, head and neck, oesophageal, cervix), renal cell carcinoma, bladder carcinoma, and some adenocarcinomas of the breast and ovary. Tumour burden of bone metastases may be minimal or absent.

Local Osteolytic Hypercalcaemia (LOH)

LOH results from direct osteolytic destruction of bone by metastatic deposits, most commonly in breast carcinoma, multiple myeloma, and non-small cell lung cancer. Tumour cells within the bone marrow microenvironment secrete a constellation of osteoclast-activating factors:

RANK-L (Receptor Activator of Nuclear Factor κB Ligand): The master regulator of osteoclast differentiation and activation. Tumour cells upregulate RANK-L expression or secrete soluble RANK-L, driving osteoclastic bone resorption.
Interleukin-1, IL-6, IL-11, TNF-α: Pro-inflammatory cytokines that amplify osteoclast activity within the tumour-bone microenvironment.
Parathyroid hormone-related peptide (PTHrP): Often co-secreted locally (autocrine/paracrine), creating an overlap between HHM and LOH mechanisms in breast cancer.
Matrix metalloproteinases (MMPs): Facilitate bone matrix degradation and tumour invasion.

Unlike HHM, LOH is characterised by extensive radiographic skeletal disease. PTHrP may be normal or only mildly elevated. Hypophosphataemia is less prominent than in pure HHM because the renal component of PTHrP action is absent.

1,25-Dihydroxyvitamin D-Mediated Hypercalcaemia

A less common mechanism (~1% of HCM) seen in Hodgkin lymphoma, some non-Hodgkin lymphomas, and granulomatous diseases. Neoplastic or activated macrophages express 1α-hydroxylase, converting 25-hydroxyvitamin D to active 1,25-dihydroxyvitamin D (calcitriol). Calcitriol increases intestinal calcium absorption and, to a lesser extent, bone resorption. PTHrP is typically normal and 1,25-(OH)₂D is elevated.

Feature	HHM (PTHrP-Mediated)	LOH (Osteolytic)
Primary mechanism	Systemic PTHrP secretion	Direct osteoclast-mediated bone destruction
Typical tumours	SCC (lung, H&N), renal cell, bladder	Breast, myeloma, NSCLC with bone mets
Bone metastases	May be minimal	Extensive radiographic disease
PTHrP level	Elevated	Normal or mildly elevated
Serum phosphate	Low (hypophosphataemia)	Normal or mildly low
Urinary calcium	High (nephrogenous hypercalciuria)	Variable
1,25-(OH)₂D	Low (suppressed)	Variable
Response to bisphosphonates	Good but may relapse sooner	Generally good and sustained

Clinical Features & Severity Classification

Clinical Features

Hypercalcaemia of malignancy produces a constellation of symptoms and signs across multiple organ systems. Symptoms may be insidious at mildly elevated levels but become increasingly severe and life-threatening as calcium rises. The mnemonic "Stones, Bones, Groans, and Psychic Moans" applies to chronic hypercalcaemia, though in the acute malignancy setting, constitutional and neuropsychiatric symptoms predominate.

System	Features
Neurological	Confusion, lethargy, depression, psychosis, seizures, coma (in severe/crisis cases)
Gastrointestinal	Anorexia, nausea, vomiting, constipation, abdominal pain, peptic ulceration
Renal	Polyuria, polydipsia, nephrogenic diabetes insipidus, acute kidney injury, nephrolithiasis
Cardiovascular	Shortened QTc on ECG, arrhythmias (bradycardia, heart block), hypertension, cardiac arrest in extreme cases
Musculoskeletal	Bone pain (especially with metastatic disease), muscle weakness, hypotonia
Constitutional	Fatigue, dehydration, weight loss

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ECG changes: Hypercalcaemia classically causes a shortened QT interval. At calcium ≥3.50 mmol/L, risk of bradyarrhythmias and cardiac arrest increases significantly. Obtain a 12-lead ECG in all patients presenting with HCM.

Severity Classification

Severity is based on corrected serum calcium levels and clinical acuity. The classification below guides urgency of intervention and setting of care.

Mild

Mild Hypercalcaemia

Corrected calcium 2.60–2.99 mmol/L. Often asymptomatic or only mildly symptomatic (mild fatigue, polydipsia). May be detected on routine surveillance bloods.

Setting: Outpatient or ward management

Moderate

Moderate Hypercalcaemia

Corrected calcium 3.00–3.49 mmol/L. Symptoms are usually present: anorexia, nausea, constipation, polyuria, mild confusion, lethargy. Dehydration common.

Setting: Hospital admission, medical ward with close monitoring

Severe

Severe Hypercalcaemia

Corrected calcium ≥3.50 mmol/L. Significant symptoms: marked confusion, obtundation, vomiting, renal impairment, ECG changes. Risk of cardiac arrest.

Setting: HDU/ICU, urgent intervention required

Critical

Hypercalcaemic Crisis

Corrected calcium ≥3.50 mmol/L with life-threatening features: coma, seizures, cardiac arrhythmias, acute renal failure. Mortality is high without immediate treatment.

Setting: ICU admission, emergent resuscitation

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Hypercalcaemic crisis is a medical emergency. Corrected calcium ≥3.50 mmol/L with altered consciousness, seizures, or cardiac arrhythmias requires immediate ICU admission, aggressive fluid resuscitation, and concurrent antiresorptive therapy. Consult critical care and oncology early.

Investigations & Diagnosis

The diagnostic approach to hypercalcaemia of malignancy aims to: (1) confirm and quantify hypercalcaemia, (2) exclude non-malignant causes (especially primary hyperparathyroidism), (3) determine the pathophysiological mechanism, and (4) assess end-organ damage.

Confirming Hypercalcaemia

Corrected calcium: Always calculate corrected calcium using the formula: Corrected Ca²⁺ = Measured Ca²⁺ + 0.02 × (40 − albumin in g/L). Albumin correction is essential because hypoalbuminaemia (common in cancer patients) causes a spuriously low measured calcium.
Ionised calcium: The gold standard. Unaffected by albumin. Use ionised calcium measurement (MBS item 66570) in acutely unwell patients, those on heparin, or when corrected calcium and clinical status are discordant.

Essential Investigations

Essential

Serum corrected calcium and ionised calcium

Confirm hypercalcaemia and monitor response to treatment. Repeat every 6–12 hours during acute management.

Essential

Serum albumin

Required for corrected calcium calculation. Also assesses nutritional status and hepatic function.

Essential

Intact PTH (iPTH)

Suppressed (<1.5 pmol/L) in HCM. If elevated or inappropriately normal, consider concurrent primary hyperparathyroidism (synchronous HPT occurs in ~1–2% of cancer patients).

Essential

PTHrP (parathyroid hormone-related peptide)

Elevated in HHM. Confirms humoral mechanism. Useful for guiding prognosis and monitoring response to anti-cancer therapy. Available through major pathology providers (MBS item 66813).

Essential

Renal function (urea, creatinine, eGFR)

Assess for acute kidney injury. Critical for determining bisphosphonate dosing and fluid resuscitation goals.

Essential

Serum phosphate

Low in HHM (mimicking primary HPT). Normal or mildly low in LOH. Distinguishes mechanisms.

Available

Serum magnesium

Hypermagnesaemia can accompany hypercalcaemia; hypomagnesaemia may impair PTH secretion and worsen neuromuscular symptoms.

Available

25-hydroxyvitamin D

Baseline vitamin D status. Deficiency is common in cancer patients and may coexist with HCM.

Available

1,25-dihydroxyvitamin D (calcitriol)

Elevated in lymphoma-mediated hypercalcaemia and granulomatous disease. Consider when PTHrP is normal.

Essential

12-lead ECG

Look for shortened QTc (<340 ms), prolonged PR, T-wave changes, bradycardia. Risk marker for cardiac complications.

Available

24-hour urinary calcium and creatinine

Nephrogenous hypercalciuria in HHM. Helps distinguish HCM from familial hypocalciuric hypercalcaemia (FHH) if diagnostic uncertainty exists.

Differential Diagnosis to Exclude

Before attributing hypercalcaemia solely to malignancy, consider and exclude:

Primary hyperparathyroidism: PTH will be elevated or inappropriately normal. Common in the community; may coexist with cancer. PTHrP is normal.
Thiazide diuretics: Reduce renal calcium excretion. Check medication history.
Vitamin D toxicity: Excessive supplementation. Check 25-OH-D and 1,25-(OH)₂D.
Granulomatous disease: Sarcoidosis, tuberculosis — macrophage-mediated 1,25-(OH)₂D production.
Immobilisation: Especially with Paget disease or high bone turnover.
Familial hypocalciuric hypercalcaemia (FHH): Benign autosomal dominant condition. Low urinary calcium excretion (calcium:creatinine clearance ratio <0.01) distinguishes it.

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Key diagnostic pattern: In a cancer patient with suppressed PTH, elevated PTHrP, hypophosphataemia, and suppressed 1,25-(OH)₂D, the diagnosis of HHM is confirmed. In a patient with extensive osteolytic bone disease, normal PTHrP, and corrected hypercalcaemia, the diagnosis of LOH is highly probable.

Management — IV Fluids, Bisphosphonates & Denosumab

Management of HCM has two parallel objectives: (1) acute calcium reduction to prevent life-threatening complications, and (2) definitive treatment of the underlying malignancy. The acute management algorithm below is applicable regardless of the pathophysiological mechanism.

Step 1 — Aggressive Intravenous Fluid Resuscitation

1

Initial Bolus

0.9% sodium chloride 1–2 L IV over 1–2 hours (rate adjusted for cardiac function and age). Rehydration addresses the dehydration component of hypercalcaemia (nephrogenic diabetes insipidus, vomiting, anorexia) and enhances renal calcium excretion.

2

Maintenance Hydration

0.9% sodium chloride 150–200 mL/hr IV (typically 200–300 mL/hr for first 24 hours in severe cases). Monitor fluid balance strictly with hourly urine output and daily weight. Target urine output ≥100–150 mL/hr to promote calciuresis.

3

Monitor for Fluid Overload

Assess JVP, lung auscultation, and chest X-ray. In patients with cardiac failure or renal impairment, central venous pressure (CVP) monitoring may guide fluid therapy. Frusemide is added ONLY for fluid overload — not as a primary calcium-lowering strategy.

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Frusemide myth: Loop diuretics were historically recommended to enhance renal calcium excretion. Current evidence does NOT support routine use of frusemide for calcium lowering. Frusemide is indicated ONLY to manage fluid overload after adequate hydration. Inappropriate use without prior volume expansion worsens hypercalcaemia through dehydration.

Step 2 — Calcitonin (Rapid Onset Therapy)

Calcitonin provides the most rapid calcium reduction (onset 4–6 hours) and is used as a bridge while awaiting the effect of antiresorptive agents (bisphosphonates or denosumab).

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Salmon Calcitonin

Miacalcic® · Calcitonin (salmon) · Calcitonin analogue

Adult dose 4–8 IU/kg SC or IM every 12 hours

Onset / duration Onset 4–6 hours · Duration 12–24 hours

Tachyphylaxis Effect diminishes after 48 hours (tachyphylaxis). Not suitable as monotherapy.

Adverse effects Flushing, nausea, injection site reaction. Allergic reactions rare. Avoid in patients with known fish allergy (precautionary).

PBS status ✔ PBS General Benefit

Step 3 — Intravenous Bisphosphonates (First-Line Antiresorptive)

IV bisphosphonates inhibit osteoclast-mediated bone resorption and are the cornerstone of antiresorptive therapy for HCM. Onset of action is 2–4 days with maximal calcium reduction at 4–7 days.

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Zoledronic Acid

Zometa® · Aclasta® (different dose indication) · Nitrogen-containing bisphosphonate

Adult dose (HCM) 4 mg IV infusion over ≥15 minutes. May repeat after 7 days if calcium remains elevated.

Renal adjustment eGFR 50–60: use with caution. eGFR 30–50: reduce to 3.5 mg. eGFR <30: avoid zoledronic acid — use denosumab instead. Ensure adequate hydration before infusion.

Onset / nadir Onset 2–4 days · Nadir calcium at 4–7 days · Duration 2–4 weeks

Adverse effects Acute phase reaction (fever, myalgia, flu-like symptoms — in ~20%), hypophosphataemia, hypocalcaemia, nephrotoxicity, osteonecrosis of the jaw (rare, cumulative), atypical femoral fracture (rare, prolonged use).

Key warning Ensure adequate hydration and check eGFR before administration. Infusion must be ≥15 minutes to reduce nephrotoxicity risk.

PBS status ⚠ PBS Authority Required

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Pamidronate

Aredia® · Pamisol® · Nitrogen-containing bisphosphonate

Adult dose (HCM) 60–90 mg IV over 2–4 hours. Dose depends on severity and baseline calcium.

Dose by severity Corrected Ca <3.0 mmol/L: 60 mg. Ca 3.0–3.5: 60–90 mg. Ca >3.5: 90 mg. May repeat after 7 days.

Renal adjustment Less nephrotoxic than zoledronic acid but still use caution in renal impairment. Consider dose reduction or denosumab if eGFR <30.

PBS status ⚠ PBS Authority Required

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Bisphosphonate selection: Zoledronic acid 4 mg IV is generally preferred over pamidronate due to greater potency and shorter infusion time. However, pamidronate may be chosen in patients with moderate renal impairment (eGFR 30–50) where zoledronic acid carries higher nephrotoxicity risk. Ensure oral calcium and vitamin D supplementation if ongoing bisphosphonate therapy to prevent hypocalcaemia.

Step 4 — Denosumab (Second-Line / Refractory HCM)

Denosumab is a fully human monoclonal antibody targeting RANK-L, the master regulator of osteoclast differentiation and activation. It is the agent of choice for bisphosphonate-refractory HCM and is preferred over bisphosphonates in patients with renal impairment (eGFR <30), as it is not cleared renally.

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Denosumab

Xgeva® · Prolia® (different indication) · Anti-RANK-L monoclonal antibody

Adult dose (HCM) 120 mg SC every 4 weeks. Additional loading doses at days 8 and 15 in the first month for HCM (per RANK-L HCM studies).

Renal adjustment No dose adjustment required. Safe in patients on dialysis. Preferred agent in eGFR <30.

Onset Onset 1–7 days · May take up to 2 weeks for full effect in HCM

Adverse effects Hypocalcaemia (monitor closely — can be severe), hypophosphataemia, osteonecrosis of the jaw (ONJ), atypical femoral fracture, cellulitis/skin infections, rebound vertebral fractures on discontinuation.

Key warning Hypocalcaemia risk: Ensure adequate calcium and vitamin D supplementation. Monitor calcium closely, especially in first 2 weeks and in patients with renal impairment.

PBS status 🔒 PBS Authority Required (Specialist)

Step 5 — Refractory Hypercalcaemia & Additional Therapies

Therapy	Indication	Notes
Cinacalcet	Parathyroid carcinoma; some PTHrP-secreting tumours	Calcimimetic. 30 mg PO BD, titrate. Limited evidence in HCM. Not PBS-listed for this indication.
Gallium nitrate	Rarely used in Australia	Inhibits bone resorption. Nephrotoxic. Largely superseded by bisphosphonates and denosumab.
Mithramycin	Rarely used	Cytotoxic, inhibits osteoclast RNA synthesis. Significant hepatotoxicity and thrombocytopenia.
Haemodialysis	Refractory HCM, renal failure, hypercalcaemic crisis unresponsive to therapy	Low-calcium dialysate. Effective rapid calcium reduction. Consult nephrology.
Prednisolone	Lymphoma-mediated or 1,25-(OH)₂D-mediated hypercalcaemia	Reduces 1α-hydroxylase activity. 25–50 mg PO daily. Ineffective for HHM or LOH.

Monitoring During Acute Management

0–6 hours

Corrected calcium, ionised calcium, creatinine, electrolytes every 6 hours. Urine output hourly. Continuous cardiac monitoring if severe.

6–24 hours

Continue 6-hourly bloods. Assess response to fluids ± calcitonin. Administer IV bisphosphonate or denosumab. Fluid balance chart.

24–48 hours

Expect response from bisphosphonate (if given). Check calcium 12-hourly. Wean IV fluids as calcium normalises and oral intake resumes. Monitor phosphate and magnesium.

48–72 hours

Nadir of bisphosphonate effect. Assess for hypocalcaemia. Transition to oral fluids. Plan definitive anti-cancer therapy. Commence osteoporosis prevention (calcium + vitamin D) if ongoing antiresorptive therapy.

7–14 days

Repeat bisphosphonate dose if calcium remains elevated. Consider denosumab if bisphosphonate-refractory. Oncology review for systemic therapy.

Quick Reference — Acute Management Algorithm

Mild (Ca 2.60–2.99)

IV fluids (0.9% NaCl 100–150 mL/hr) ± bisphosphonate

24–48 hrs

May manage as outpatient if stable

Moderate (Ca 3.00–3.49)

IV fluids (150–200 mL/hr) + calcitonin + zoledronic acid 4 mg IV

48–72 hrs

Hospital admission, cardiac monitoring if symptomatic

Severe (Ca ≥3.50)

IV fluids (200–300 mL/hr) + calcitonin + zoledronic acid (or denosumab if renal impairment)

ICU/HDU

Continuous cardiac monitoring, 6-hourly bloods, consider dialysis

Special Populations

🩺 Renal Impairment

Fluid management: Aggressive hydration carries risk of fluid overload in CKD. Use CVP monitoring or clinical assessment of volume status to guide fluid rates.

Bisphosphonates: Zoledronic acid requires dose reduction (3.5 mg if eGFR 30–50) and is contraindicated if eGFR <30 due to nephrotoxicity. Pamidronate is less nephrotoxic but still requires caution.

Preferred agent: Denosumab is the preferred antiresorptive agent in patients with eGFR <30 or on dialysis — no renal dose adjustment required.

Hypocalcaemia risk: Denosumab can cause severe hypocalcaemia in renal impairment. Monitor ionised calcium closely. Ensure adequate vitamin D repletion.

Dialysis: Haemodialysis with low-calcium dialysate is effective for refractory cases. Consult nephrology early.

👴 Elderly Patients

Fluid overload: Higher risk of pulmonary oedema with aggressive hydration. Titrate fluid rates carefully and monitor for signs of cardiac decompensation.

Falls and fractures: Hypercalcaemia-related weakness and confusion increase fall risk. Bisphosphonates and denosumab carry risk of atypical femoral fractures with prolonged use.

Polypharmacy: Review medications — thiazide diuretics, calcium supplements, vitamin D analogues may worsen hypercalcaemia.

Goals of care: In frail elderly patients with advanced malignancy, discuss goals of care early. Aggressive calcium correction may provide symptomatic relief even if prognosis is limited.

🦠 Immunocompromised Patients

Calcitonin: Not contraindicated in immunosuppression. Can be used as bridging therapy.

Bisphosphonates: Do not cause immunosuppression. Acute phase reaction (fever, myalgia) may complicate infection assessment — ensure fevers are not attributed solely to bisphosphonate if infection is possible.

Denosumab: Associated with increased risk of cellulitis and skin infections. Monitor for infection, particularly in patients on concurrent immunosuppressive therapy.

Prophylaxis: If patient is neutropenic, ensure appropriate antimicrobial prophylaxis is in place during hospital admission.

🫁 Hepatic Impairment

Albumin: Hepatic synthetic dysfunction causes hypoalbuminaemia, making uncorrected calcium unreliable. Use ionised calcium for monitoring.

Bisphosphonates: No hepatic dose adjustment required for zoledronic acid or pamidronate. However, hepatic impairment may affect drug metabolism in complex ways — monitor closely.

Denosumab: Not hepatically metabolised. No dose adjustment required.

Coagulopathy: If platelet count is low or INR prolonged, intramuscular injections (e.g., calcitonin IM) should be given via SC route instead.

👶 Paediatric Patients

Aetiology: HCM in paediatric oncology is less common than in adults. Most often seen in neuroblastoma, rhabdomyosarcoma, and certain leukaemias. PTHrP-mediated HHM and osteolytic mechanisms both occur.

Fluids: Use weight-based fluid resuscitation. 0.9% sodium chloride 20 mL/kg bolus, then maintenance + replacement. Monitor fluid balance meticulously.

Calcitonin: Paediatric dose: 4 IU/kg SC/IM every 12 hours (same as adult dosing on a weight basis).

Bisphosphonates: Zoledronic acid is not routinely TGA-approved for paediatric HCM. Pamidronate 0.5–1 mg/kg IV over 2–4 hours is used off-label in specialist centres. Consult paediatric oncology.

Denosumab: Not established in paediatric HCM. Use only in specialist paediatric oncology settings with ethics/governance approval.

Aboriginal and Torres Strait Islander Health Considerations

Aboriginal and Torres Strait Islander Health

Aboriginal and Torres Strait Islander Australians experience a disproportionate cancer burden, with higher incidence, later stage at diagnosis, and poorer survival outcomes compared to non-Indigenous Australians. The AIHW reports that Indigenous Australians are 1.4 times more likely to be diagnosed with cancer and 1.6 times more likely to die from cancer. These disparities are driven by systemic barriers to healthcare access, higher prevalence of comorbidities, and the impacts of intergenerational trauma and socioeconomic disadvantage.

Relevance to Hypercalcaemia of Malignancy

Later stage at diagnosis means that Indigenous Australians are more likely to present with advanced malignancy, including complications such as hypercalcaemia. Higher rates of renal disease (CKD is 2.3 times more prevalent in Indigenous Australians) create additional management challenges, as renal impairment complicates both the hypercalcaemia itself and the antiresorptive therapies used to treat it.

Geographic access

Many Indigenous Australians live in remote or very remote areas with limited access to oncology services, IV infusion facilities, and pathology monitoring. Bisphosphonate infusion may require aeromedical retrieval or coordination with local health services (e.g., Aboriginal Community Controlled Health Organisations — ACCHOs).

Renal comorbidity

Higher prevalence of CKD in Indigenous communities requires careful selection of antiresorptive agents. Denosumab (no renal dose adjustment) is preferred over zoledronic acid in patients with eGFR <30, but access and cost may be barriers in remote settings.

Cultural safety

Communication about life-threatening cancer complications must be delivered in a culturally safe manner, with respect for the patient's and family's wishes regarding information sharing, decision-making, and end-of-life care. Engage Aboriginal and Torres Strait Islander Health Workers or Liaison Officers in all aspects of care.

Health literacy

Use plain language and visual aids when explaining hypercalcaemia, its symptoms, and treatment. Provide written information in accessible formats. Consider language and translation services where English is not the first language.

Follow-up and monitoring

Ensure that calcium monitoring post-discharge is arranged through the local ACCHO or primary health service. Telehealth can facilitate specialist oncology review for remote patients. Use the Closing the Gap PBS co-payment measure to reduce medication costs.

Data and research

Cancer outcomes data specific to Indigenous Australians with HCM are limited. The Cancer Council Australia and AIHW Cancer in Aboriginal & Torres Strait Islander peoples reports provide the best available national data. Participate in data collection and quality improvement initiatives that include Indigenous identifiers.

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Key actions for culturally safe care: (1) Ask about Aboriginal or Torres Strait Islander status respectfully at first contact. (2) Engage Indigenous Health Workers in the care team. (3) Use Closing the Gap PBS co-payment for medication access. (4) Plan follow-up through ACCHOs or local health services. (5) Respect cultural protocols around death, dying, and family involvement in care decisions.

📚 References

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