[1] These structural changes cause the bone to weaken, which may result in deformity, pain, fracture or arthritis of associated joints.

Although there is no cure for Paget's disease, medications (bisphosphonates and calcitonin) can help control the disorder and lessen pain and other symptoms.

[9] Paget's disease affecting the skull may cause frontal bossing, increased hat size, and headaches.

[18] Laboratory contamination may have played a role in past studies linking paramyxovirus (e.g. measles) to Paget's disease.

[9] About 40–50% of people with the inherited version of Paget's disease have a mutation in the gene SQSTM1, which encodes a protein, called p62, that is involved in regulating the function of osteoclasts (bone cells).

[22] Additional genetic associations include: The pathogenesis of Paget's disease is described in four stages:[24] Initially, there is a marked increase in the rate of bone resorption in localized areas, caused by large and numerous osteoclasts.

Some evidence suggests that a paramyxovirus infection is the underlying cause of Paget's disease,[7] which may support the possible role of inflammation in the pathogenesis.

However, no infectious virus has yet been isolated as a causative agent, and other evidence suggests an intrinsic hyperresponsive reaction to vitamin D and RANK ligand is the cause.

[7] Paget's disease may be diagnosed using one or more of the following tests: Although initially diagnosed by a primary care physician, endocrinologists (internal medicine physicians who specialize in hormonal and metabolic disorders), rheumatologists (internal medicine physicians who specialize in joint and muscle disorders), orthopedic surgeons, neurosurgeons, neurologists, oral and maxillofacial surgeons, and otolaryngologists are generally knowledgeable about treating Paget's disease and may be called upon to evaluate specialized symptoms.

In one study it was reported that people experienced side effects when taking bisphosphonates for six months, however the quality of evidence was low.

[citation needed] Salcatonin, also called calcitonin-salmon is a synthetic copy of a polypeptide hormone secreted by the ultimobranchial gland of salmon.

As a solution for injection or infusion, calcitonin should be administered for no more than 4 weeks to prevent acute bone loss resulting from sudden immobilization, and normally for no more than 3 months to treat Paget's disease, the EMA said.

[30] In 2014, the FDA noted the risk imbalances in the prescribing information for Miacalcin but declined to label this product with a boxed warning as a causal association was not identified.

[31] A more recent meta-analysis determined that a causal link between calcitonin and cancer is both unlikely and antithetical to known biology, although a weak association was not definitively excluded.

A phase III trial found no difference between placebo and nasal calcitonin sprays on lumbar bone mineral density in osteoporosis.

[citation needed] In general, patients with Paget's disease should receive 1000–1500 mg of calcium, adequate sunshine, and at least 400 units of vitamin D daily.

[citation needed] The disease is progressive and slowly worsens with time, although people may remain minimally symptomatic.

Osteogenic sarcoma, a form of bone cancer, is a rare complication of Paget's disease occurring in less than one percent of those affected.

[38] Evidence from studies of autopsy results have demonstrated Paget's disease in about 3 percent of people older than 40 years of age.

[38] Paget's disease is uncommon in the native populations of North and South America, Africa, Asia, and the Middle East.

[39] Strikingly, the first patient was described to have many of the classic complications of the disease, including arthritis related to abnormal bone mechanics, cranial nerve palsies associated with an enlarging skull, and malignant transformation of a tumor of the radius which ultimately proved fatal.

Holding, then, the disease to be an inflammation of bones, I would suggest that, for brief reference, and for the present, it may be called, after its most striking character, Osteitis deformans.

A better name may be given when more is known of it.Paget's disease of bone was originally termed osteitis deformans, because it was thought to involve an inflammatory process, which is implied by the suffix -itis.