In which condition are calcium levels high due to immobilization?

In the context of immobilization, high calcium levels can occur due to the increased resorption of bone that is often associated with disuse and lack of mechanical loading. This phenomenon is particularly prominent in Paget's disease of bone, which is characterized by abnormal bone remodeling. In Paget's disease, there is rapid bone turnover that can result in elevated levels of calcium in the blood, especially when immobilization or decreased activity occurs.

Paget's disease leads to an increase in osteoclastic activity, which breaks down bone tissue and can release calcium into the bloodstream. When a patient is immobilized, the mechanical stress that usually helps to maintain bone density decreases, resulting in further stimulation of osteoclast activity. Therefore, the combination of Paget's disease and immobilization can lead to hypercalcemia.

In contrast, conditions like acute renal failure can lead to metabolic disturbances, but hypercalcemia is not typically a direct consequence of immobilization. Hypoparathyroidism leads to low calcium levels due to insufficient parathyroid hormone, and osteolytic metastasis, while capable of causing hypercalcemia due to the breakdown of bone, is not directly associated with immobilization in the same way Paget’s disease is.