What is meant by osteolytic hypercalcemia?

Related Media. Listen to the Audiocast. Hypercalcemia is defined as a condition in which the serum calcium level is >10.5 mg/dL (the upper limit of normal) or the ionized calcium level exceeds 5.6 mg/dL. The consequences of abnormally high serum calcium can range from asymptomatic to life-threatening.

Why do malignancies cause hypercalcaemia?

The pathophysiology of hypercalcemia of malignancy is mainly through three mechanisms: excessive secretion of parathyroid hormone-related protein (PTHrP), bony metastasis with the release of osteoclast activating factors, and production of 1,25-dihydroxy vitamin D (calcitriol).

How does squamous cell carcinoma cause hypercalcemia?

Squamous carcinomas are the most common malignancies that cause humoral-mediated hypercalcemia of malignancy. The major humoral factor is parathyroid hormone-related peptide (PTHrP), a protein that has similar action to parathyroid hormone (PTH) but a completely different structure.

How does local osteolytic hypercalcemia of malignancy occur?

Local osteolytic hypercalcemia, which occurs in approximately 20% of HCM cases, results from increased osteoclastic bone resorption in areas surrounding the malignant cells within the marrow space. Although the bone destruction is mediated primarily by osteoclasts, tumor cells also produce factors that induce osteoclast activity. 8,9

What causes bone pain in patients with hypercalcemia?

Bone pain can occur in patients with hyperparathyroidism or malignancy. Osteoporosis of cortical bone, such as the wrist, is mainly associated with primary hyperparathyroidism. 9 Excess PTH also can result in subperiosteal resorption, leading to osteitis fibrosa cystica with bone cysts and brown tumors of the long bones.

How is hypercalcemia related to the treatment of cancer?

Local osteolytic hypercalcemia (LOH) causes about 20% of hypercalcemia associated with cancer, though the incidence may be decreasing with the widespread use of bisphosphonates. Hypercalcemia in LOH results from release of cytokines within the marrow space that recruit and activate osteoclasts.

Are there any medications that can cause hypercalcemia?

Medications which can result in hypercalcemia include: Thiazide diuretics, which often cause mild hypercalcemia due to increases renal tubular calcium reabsorption. Aminophylline and theophylline, which have been reported to cause mild, transient hypercalcemia through unknown mechanisms when used in supra-therapeutic doses.