Malignant Hypercalcaemia
Questions
- Are they able to eat and/or drink?
- Urinary symptoms – Polyuria or Polydipsia?
- Any vomiting?
- Any recent weight loss?
- Assess bowel movements; any suggestions of constipation?
- Sudden onset confusion?
- Extent of known disease? e.g. known bone/liver metastases
- What medication are they taking? Thiazide diuretics, calcium, vitamin A & vitamin D supplements can all increase calcium levels
Grade 1 (Green)
Corrected serum calcium of:
> ULN 2.9 mmol/L;
Advice
If corrected calcium 2.6-2.69 and patient is asymptomatic; recheck in 2 days and treat if rising OR if the patient becomes symptomatic.
Oral rehydration may be all that’s needed in mild asymptomatic cases.
If ≥ 2.7 – 2.9 consider IV fluids +/- bisphosphonates. If the patient is well, this can be given as an outpatient; if not, will need admission
Grade 2 (Amber)
Corrected serum calcium of:
>2.9-3.1 mmol/L;
Advice
If corrected calcium 2.6-2.69 and patient is asymptomatic; recheck in 2 days and treat if rising OR if the patient becomes symptomatic.
Oral rehydration may be all that’s needed in mild asymptomatic cases.
If ≥ 2.7 – 2.9 consider IV fluids +/- bisphosphonates. If the patient is well, this can be given as an outpatient; if not, will need admission
Grade 3 (Red)
Corrected serum calcium of:
>3.1- 3.4 mmol/L
Advice
Admit patient for further assessment, IV fluids and bisphosphonates
Grade 4 (Red)
Corrected serum calcium of:
> 3.4 mmol/L
Advice
Admit patient for further assessment, IV fluids and bisphosphonates
Handover management with patient’s team, discuss all interruptions of treatment with team +/- AOS prior to proceeding. Arrange follow up review as necessary.
Initial assessment – patient seen in AOCU
- History of complaint/symptoms
- Check all prescribed medication and if on any thiazide diuretics, calcium, vitamin A or vitamin D supplements stop these medications
- Assessment of fluid balance status (BP, pulse etc..)
- Check bloods – Bone profile, Renal function, LFTs, Magnesium.
- ECG
Treatments
IV Fluids – Intravenous rehydration for 24 hours with 0.9% saline, 4-6L.
- Normal saline hydration corrects volume depletion from calcium-induced diuresis and decreased fluid intake; promotes renal calcium excretion.
- This intervention reduces serum calcium by a median of 0.25 mmol/L.
- The routine use of furosemide in conjunction with hydration to promote calcium excretion is not recommended, because of the risk of volume and electrolyte depletion.
- Rehydration may provoke hypokalaemia and hypomagnesaemia, so check U&Es and Mg++ daily and replace as necessary
- Consider catheterisation if patient does not pass urine for 4 hours.
Bisphosphonates – Zoledronic Acid 4mg in 50 ml 0.9% saline over 15 minutes is the standard dose.
In renal impairment dose may need to be reduced – CHECK WITH PHARMACY BEFORE GIVING
- Bisphosphonates are the mainstay of treatment of hypercalcaemia.
- These drugs are pyrophosphate analogues that bind to hydroxyapatite crystals in bone matrix and inhibit osteoclastic bone resorption.
- Resistance to bisphosphonates may occur due to the fact that bisphosphonates do not reduce PTHrP-induced renal calcium re-absorption.
- Bisphosphonates are appropriate to administer when serum calcium is ≥ 3.0 mmol/L, or when a serum calcium of < 3.0 mmol/l is accompanied by symptoms.
- Renal failure is the most serious potential adverse effect. Therefore, dehydration should be corrected and serum creatinine checked prior to administration.
Bisphosphonates will usually begin to reduce Ca++ within 48 hours and will usually normalise it within 5 days. If the Ca++ level is not falling, DO NOT REPEAT THE DOSE UNTIL AT LEAST DAY 5.
Dietary calcium does not need to be restricted. However, calcium supplements should be discontinued. Hypercalcaemia of malignancy occurs as a consequence of osteolysis and renal tubular reabsorption of calcium. The contribution of dietary calcium is negligible.
