Can bone metastases cause high calcium in cancer?

This complication is called hypercalcaemia of malignancy. Cancer can also raise calcium through chemical signals even without extensive bone involvement, so a blood test and clinical assessment are needed to establish the cause.

Calcium helps nerves, muscles and the heart work normally. When too much circulates in the blood, the kidneys lose more water and the digestive and nervous systems may slow down. Symptoms can include marked thirst, frequent urination, dehydration, constipation, nausea, poor appetite, fatigue, muscle weakness, drowsiness or confusion.

These symptoms are not specific to high calcium and can overlap with medicine effects, infection or the cancer itself. Blood testing measures calcium, and clinicians may interpret it alongside albumin, kidney function and other results.

Contact the oncology team on the same day if compatible symptoms are new or getting worse. Do not start calcium or vitamin D supplements, stop prescribed products, or force large amounts of fluid without advice; kidney or heart conditions can change what is safe.

Treatment may include fluids through a vein, medicines that reduce calcium release from bone, and therapy directed at the cancer. The team also manages dehydration, kidney strain, nausea and other effects, then repeats blood tests to check the response.

Seek urgent medical assessment for increasing sleepiness, confusion, severe weakness, repeated vomiting, inability to keep fluids down, very little urine or signs of substantial dehydration. High calcium can worsen quickly and may affect kidney, brain and heart function.

Call emergency services if the person is difficult to wake, collapses, has a seizure, develops severe shortness of breath or has a new abnormal heartbeat sensation with faintness. Bring the medicine and supplement list if it is readily available.

Ask what the corrected or ionised calcium result means, whether kidney function is affected, which medicines or supplements need adjustment, what fluid intake is suitable, how treatment addresses the bone metastases, and when blood tests will be repeated.