Osteitis Fibrosa Cystica

Osteitis fibrosa cystica ( /ˌɒstiːˈaɪtɨs faɪˈbroʊsə ˈsɪstɨkə/), abbreviated OFC, and also known as osteitis fibrosa, osteodystrophia fibrosa, Von Recklinghausen's Disease of Bone, not to be confused with Von Recklinghausen's disease (neurofibromatosis type I). Osteitis Fibrosa Cystica is a skeletal disorder caused by a surplus of parathyroid hormone from over-active parathyroid glands. This surplus stimulates the activity of osteoclasts, cells that break down bone, in a process known as osteoclastic bone resorption. The over-activity of the parathyroid glands (hyperparathyroidism) can be triggered by parathyroid adenoma, hereditary factors, parathyroid carcinoma, or renal osteodystrophy. Osteoclastic bone resorption releases minerals, including calcium, from the bone into the bloodstream. In addition to elevated blood calcium levels, over-activity of this process results in a loss of bone mass, a weakening of the bones as their calcified supporting structures are replaced with fibrous tissue (peritrabecular fibrosis), and the formation of cyst-like brown tumors in and around the bone. The symptoms of the disease are the consequences of both the general softening of the bones and the excess calcium in the blood, and include bone fractures, kidney stones, nausea, appetite loss, and weight loss.

First described in the nineteenth century, OFC is currently detected through a combination of blood testing, X-rays, and tissue sampling. Before 1950, around half of those diagnosed with hyperparathyroidism in the United States saw it progress to OFC, but with early identification techniques and improved treatment methods, instances of OFC in developed countries are increasingly rare. Where treatment is required, it normally involves addressing the underlying hyperparathyroidism before commencing long-term treatment for OFC—depending on its cause and severity, this can range from hydration and exercise to surgical intervention.