In all patients:
- correct hypophosphataemia,
- consider therapy for recurrent or chronic hypercalcaemia,
- intermittent IV bisphosphonate depending on recurrence of hypercalcaemia,
- oral clodronate, and
- encourage oral hydration.
Patients with hypercalcaemia associated with cancer are substantially dehydrated as a result of a renal water-concentrating defect induced by hypercalcaemia and by decreased oral hydration resulting from anorexia and nausea, vomiting or both. The dehydration leads to a reduction in the glomerular filtration rate that further reduces the ability of the kidney to excrete the excess serum calcium. Rehydration reverses this situation and is a critical component of therapy.r
Forced saline diuresis
This treatment is NOT recommended as a routine. Forcing sodium excretion by renal tubules by the administration of saline infusion and diuretics blocks calcium reabsorption in the loop of Henle. This treatment should only be used after the patient is hydrated. Forced saline diuresis is potentially dangerous since it may cause a worsening of hypercalcaemia if dehydration is induced or fluid overload if insufficient diuretic is administered.
Bisphosphonates bind to the bone matrix and inhibit osteoclast action and therefore bone resorption. It is important to remember that they have no effect on the renal mechanism of hypercalcaemia. After bisphosphonate treatment the serum calcium level will begin to fall within 12 hours after the therapy is initiated and will reach the nadir within approximately four to seven days. The serum calcium level generally will remain in the normal or near-normal range for one to three weeks.r
Zoledronic acid is marginally superior to pamidronate in terms of percentage and length of control.
Sodium clodronate is available as an oral therapy (initially sodium clodronate 2400-3200 mg PO daily - on an empty stomach - then reduce to 1600 mg daily).
Calcitonin blocks osteoclast activity and also renal tubular reabsorption of calcium. It is the only therapy that has a dual effect. Calcitonin effect is rapid, usually within a few hours of first administration. Unfortunately, tolerance develops and the effect rarely last for more than a week despite continued use.
Salcatonin may be administered as:
- 5 to 10 IU per kg daily by slow IV infusion in 500 mL sodium chloride 0.9% over 6 hours OR
- slow IV injection in 2 to 4 divided doses spread over the day OR
- SC or IM injections (the same daily dose may be given as one or more injections).
Patient may require antiemetics as nausea is a common side effect of salcatonin.