Calcitonin inhibits osteoclasts and can be used therapeutically for treatment of osteoporosis and hyperparathyroidism. Osteoclasts are responsible for removing "old bone". Osteoporosis may occur when the removal of "old bone" is greater than the creation of "new bone". By inhibiting osteoclasts, the bone is able to create "new bone" at a faster rate. Similarly, hyperparathyroidism is likely to cause hypercalcemia, which is in part due to the activation of osteoclasts. Thus, calcitonin may be used to take blood calcium levels back down to baseline.