Cancer in the bones can also cause the release of large amounts of calcium into the blood. This can cause nausea, vomiting, loss of appetite, metallic taste in the mouth, constipation, muscle weakness, excessive thirst and the passing of large volumes of urine.
Again, there are a number of other possible causes for high blood calcium levels which your doctor would have to consider.
If bone secondaries are suspected, X-rays or bone scans, or both, may be necessary. X-rays of a bone secondary may show a weakened area which looks darker than the normal white bone, because there is less calcium in the affected spot. Sometimes, however, the nearby normal bone reacts very strongly to the presence of cancer cells, producing a calcium-rich area that looks whiter than the normal bone. After successful treatment, healing bone secondaries can also look like this. In some cases bone secondaries do not show up on normal X-rays at all. Quite a lot of bone has to be destroyed before they can be seen. A CT scan of the suspected area is more sensitive, and may be positive when the plain X-ray looks normal.