 Osteitis fibrosa cystica / ˌɒstiːˈaɪtᵻs faɪˈbroʊsə ˈsɪstᵻkə / , abbreviated OFC , also known as osteitis fibrosa , osteodystrophia fibrosa , and Von Recklinghausen 's disease of bone ( not to be confused with Von Recklinghausen 's disease , neurofibromatosis type I ) , is a skeletal disorder caused by hyperparathyroidism , which is 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 hyperparathyroidism can be triggered by a 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 , moth @-@ eaten appearance in the bones , appetite loss , and weight loss . 
