What to expect from bone-strengthening therapy for high calcium in cancer

Cancer can increase the breakdown of bone, releasing calcium into the bloodstream. Bone-strengthening medicines reduce this bone breakdown, so they can help lower calcium. They may be given through a vein or by injection, depending on the medicine and your clinical situation. Fluids and other treatments may be used alongside them, particularly when calcium is causing dehydration or affecting kidney function.

The effect is assessed with repeat blood tests rather than by symptoms alone. Your clinicians may review calcium, kidney function and medicines that can influence calcium. Drowsiness, constipation, nausea, thirst and weakness can occur with high calcium, but they can also have other causes.

Follow the drinking guidance given by your team; do not force fluids if you have been told to restrict them. Tell staff about kidney disease, heart problems, supplements and medicines such as calcium or vitamin D before treatment. Keep a note of confusion, nausea, constipation, thirst and urine changes. Take prescribed medicines as directed, and avoid changing supplements without advice. Arrange help with driving if you feel drowsy or weak.

High calcium can become an emergency. Seek urgent care for new confusion, difficulty staying awake, fainting, severe vomiting, marked weakness, chest symptoms, or very little urine. Contact your oncology team promptly if thirst, constipation, nausea, muscle weakness or worsening fatigue continues. After an infusion or injection, report breathing difficulty, facial swelling or a widespread rash immediately.

Ask what is causing the high calcium, which treatment is being combined with the bone-strengthening medicine, and when your next blood test is due. Ask how much fluid is appropriate for you, whether supplements should pause, and which symptoms require the emergency department.