There are many causes of raised calcium levels, the most common being overactive parathyroid glands, which secrete too much parathyroid hormone. This hormone helps control the amount of calcium in your body. When too much parathyroid hormone is secreted, your bones may lose calcium and the levels of calcium in your blood and urine rise. Read more about overactive parathyroid glands (also called hyperparathyroidism).
People with cancers such as lung cancer or breast cancer are at increased risk of having hypercalcaemia.
Other less common causes include:
- medicines such as diuretics (water tablets) or lithium
- too much calcium or vitamin D in the diet, usually as a result of taking supplements
- severe dehydration
- kidney problems
- other diseases such as tuberculosis and sarcoidosis
- being inactive, such as spending a lot of time sitting or lying in bed.