HYPERCALCAEMIA

Definiton an elevated ionised calcium concentration needs correction for low albumin (protein bound) but lab will usually report corrected level normal corrected Ca 2+ : mmol/l

Epidemiology 10% cancer patients hypercalcaemia of those who do, 80% die within one year median survival three months most will have disseminated disease most common cancers associated are: -myeloma (50%) -breast (50%) -lung -renal

Causes bone metastases -only causes 80% cases -osteolytic factors/bone resorption -extent of bone metastases does not correlate with level of calcium non bone metastases -causes 20% cases -humoral factors produced by cancer -parathyroid hormone related peptide (PTHrP) -cytokines, Interleukin 1 and 6, tumour necrosis factors etc

Why is it an emergency? distressing -disorientation/delirium/drowsiness life shortening (even more shortening) -cardiac arrhythmia/renal failure/coma especially if > 4.0 mmol/l symptoms reversible -with appropriate Rx -prevent a horrible death

How to recognise it lethargy/malaise/drowsiness nausea and vomiting anorexia thirst/polyuria constipation delirium/confusion Ileus

How to diagnose it high index of suspicion especially if recent change in symptoms think about it, especially in myeloma, breast cancer, lung cancer not all constipation is opioid induced not all lethargy is directly due to cancer measure serum calcium level – may not be possible or practical out-of-hours (OOH)

Management in OOH setting Assess the patient – consider: is it justified to Rx if patient is moribund? previous good quality of life? patient willing to have blood tests/IV Rx? can blood test wait till next day or are they too ill or symptomatic? increase oral fluid intake if possible level of hypercalcaemia (usually Rx if >2.8mmol/l)

Arranging admission urgent hospital/oncological referral

'Modern' hospice/hospital treatments IV fluid (normal saline) replacement -increases glomerular filtration rate in kidneys -promotes a sodium-linked calcium diuresis IV bisphosphonates -inhibit osteoclast activity and bone resorption -bind onto bone surface (hydroxyapatite) for weeks/months -given IV as poor GIT absorption

Bisphosphonates First generation etidronate, clodronate Second generation pamidronate Third generation zolendroic acid: -more potent ( x) and efficacious -lowers serum calcium faster -shorter infusion time (five mins vs two hrs) -side effects – pyrexia, flu-like Sx

Take home message hypercalcaemia is not always easy to diagnose – Sx are non specific need to have a high index of suspicion think about it in any unwell cancer patient, but especially if they have myeloma, breast or lung cancer urgent referral and treatment is very effective in reducing distress to patients