Hyperparathyroidism (overactive parathyroid glands) is the most common cause of excess calcium in the blood. Granulomatous lung diseases such as sarcoidosis and tuberculosis may cause vitamin D level in the blood to increase. As a result, the body absorbs more calcium and the levels in the blood also rise. Additionally, taking too much vitamin D or calcium in supplement form can lead to hypercalcemia, as can taking an excessive amount of calcium carbonate, which is in many over-the-counter antacids. Certain medications, breast cancer, lung cancer, and cancers of the blood can also lead to high calcium levels in the blood. Dehydration may lead to mild cases.

Jaykayl / Getty Images
This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.