also known as marble bone disease
and Albers-Schonberg disease
is an extremely rare inherited disorder
whereby the bones
harden, becoming denser
, in contrast to the more prevalent osteomalacia
, in which the bones soften.
It can cause osteosclerosis.
Normally, bone growth
is a balance between osteoblasts
(cells that create bone tissue) and osteoclasts
(cells that destroy bone tissue). Sufferers of osteopetrosis have a deficiency
of osteoclasts, meaning too little bone is being resorbed, resulting in too much bone being created.
Despite this excess bone formation, people with osteopetrosis tend to have bones that are more brittle than normal. Mild osteopetrosis may cause no symptoms, and present no problems. However, serious forms can result in stunted growth, deformity, increased likelihood of fractures
, and anemia
. It can also result in blindness
, facial paralysis
, and deafness
, due to the increased pressure put on the nerves
by the extra bone.
There are three major clinical forms:
The differential diagnosis
includes other disorders which can cause diffuse osteosclerosis, such as hypervitaminosis D
, and hypoparathyroidism
, Paget's disease
, diffuse bone metastasis
or prostate cancer
(which tend to be osteoblastic while most metastases are osteolytic
), intoxication with fluoride
, and hematological disorders such as myelofibrosis
, sickle cell disease
There is no cure, although curative therapy with bone marrow transplantion
is being investigated in clinical trials . It is believed the healthy marrow will provide the sufferer with cells from which osteoclasts will develop.
If complications occur or in children, patients can be treated with vitamin D. Gamma interferon has also been shown to be effective, and it can be associated to vitamin D. Erythropoetin has been used to treat any associated anemia. Corticosteroids may alleviate both the anemia and stimulate bone resorption. Fractures and osteomyelitis can be treated as usual.