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hypercalcaemia_malignancy

hypercalcaemia of malignancy

common oncologic causes:

  • breast carcinoma
  • squamous cell carcinoma lung
  • lymphoma
  • renal cell carcinoma

summary:

  • most common metabolic emergency in Oncology
  • symptoms if rapid rise or very high levels > 3.0 mmol/l
  • cardiac, neural, muscular neurophysiology altered
  • Mechanism:
    • bony involvement: M. myeloma, Breast, Lung
    • parathormone like substance: Squamous cell lung
    • osteoclast activating factor: Lymphoma
  • 40 % of patients with Multiple myeloma/ Breast

symptoms:

  • little correlation between Ca ++ levels and presence/severity of symptoms
  • Acute increase : 
    • marked CNS: personality ⇒ coma
  • Chronic increase : 
    • General: itch
    • Neuro: fatigue, weakness, apathy, perception + behaviour change, stupor, coma
    • Renal: polyuria, polydipsia
    • GIT: anorexia, nausea, vomiting, constipation, pain

signs:

  • altered mental state, confusion, coma means rapid/high level of calcium

investigations

  • ionized calcium is responsible for neuromuscular dysfunction
    • ⇒ interpret with Se. albumin, pH + phosporus
    • IONIZED Ca++ = measured Ca++ + (40 – serum albumin g/l) x 0.02
      • > 3.0 corrected ⇒ consider inpatient treatment
  • ECG: short QT interval
  • U + E: 
    • to ensure adequacy of response to fluids and diuretics
    • exclude concomitant hypokalaemia

management:

  • aims:
    • 1) Rehydration 
    • 2) increase Ca++ excretion 
    • 3) decrease Ca++ removal from bone
    • 4) decrease Ca++ intake 
    • 5) Rx underlying malignancy
  • consider CVP + PAP monitoring +/- IDC
  • rehydrate:
    • IV fluids (1⇒ 2 L NS rapidly, aim 3-6 l/day):
      • Rate depends on fluid status/CVP, UO, cardiac Fx
    • most malignancy induced ­ Ca++ responds (stimulates renal tubular Ca++ secretion)
  • once rehydrated:
    • IV frusemide 80mg
      • ⇒ renal Ca++ excretion (req. N renal FX- 100ml/hr)
  • replace K+/Mg++ may fall rapidly with rehdration/diuretics
  • bisphosphonates (on ward) ⇒ bind to hydroxyapatite, inhibits osteoclast activity
  • haemodialysis/peritoneal dialysis against a low/no calcium dialysate
  • treatment of underlying malignancy (except breast, cease radiotherapy until calcium level normalises )
  • corticosteroids for long term control
hypercalcaemia_malignancy.txt · Last modified: 2009/08/23 13:50 (external edit)