Updated: Oct 29, 2009
Paget disease is a localized disorder of bone remodeling that typically begins with excessive bone resorption followed by an increase in bone formation. This osteoclastic activity followed by compensatory bone formation (osteoblastic activity) leads to a structurally disorganized mosaic of bone (woven bone), which is weaker mechanically, larger, less compact, more vascular, and more susceptible to fracture than normal adult lamellar bone.
Sir James Paget first described chronic inflammation of bone as osteitis deformans in 1877. Paget disease, as the condition came to be known, is the second most common bone disorder (after osteoporosis) in elderly persons.
Approximately 70-90% of persons with Paget disease are asymptomatic; however, a minority of affected individuals experience various symptoms, including bone pain (the most common symptom), secondary osteoarthritis (when Paget disease occurs around a joint), bony deformity (most commonly bowing of an extremity), excessive warmth (due to hypervascularity), and neurologic complications (caused by the compression of neural tissues). Paget disease may be monostotic (17%) but is more frequently multifocal, with predilection for the axial skeleton (ie, spine, pelvis, femur, sacrum, and skull in descending order of frequency). However, any bone may be affected. After onset, Paget disease does not spread from bone to bone, but it may become progressively worse at preexisting sites.
Although the etiology of Paget disease is unknown, both genetic and environmental contributors have been suggested. Ethnic and geographic clustering of Paget disease is well described. Paget disease is common in Europe (particularly Lancashire, England), North America, Australia, and New Zealand. It is rare in Asia and Africa, and most, although not all, Americans with Paget disease are white. A familial link for Paget disease was first reported by Pick in 1883, who described a father-daughter pair with Paget disease. This was followed shortly thereafter with a sibling case of Paget disease described by Lunn in 1885. Approximately 40% of persons with Paget disease report a family history of the disease, although the true prevalence of the disease is likely higher. Some studies suggest a genetic linkage for Paget disease located on chromosome arm 18q, although this has not been demonstrated in most families with Paget disease, which suggests genetic heterogeneity.
An environmental trigger for Paget disease has long been considered but never proven. Results from bone biopsies in patients with Paget disease demonstrate several different Paramyxoviridae viral antigens, including measles virus and respiratory syncytial virus, located within osteoclasts. However, the putative antigen or antigens remain unknown.
Three phases of Paget disease have been described. Paget disease begins with the lytic phase, an increase in bone resorption with an abnormality in the osteoclasts found at the site of bony involvement. These osteoclasts are more numerous and have many more nuclei (up to 100) than normal osteoclasts (5-10 nuclei). This results in a bone turnover rate up to 20 times more rapid than normal. This significant increase in bone resorption leads to a second phase (known as the mixed phase) of rapid increases in bone formation with numerous osteoblasts, which are increased in number but remain morphologically normal. The newly made bone is abnormal; the newly formed collagen fibers are deposited in a haphazard fashion rather than linearly (as with normal bone formation).
In the final phase of Paget disease, known as the sclerotic phase, bone formation dominates and the bone that is formed has a disorganized pattern (woven bone) and is weaker than normal adult bone. This woven bone pattern allows the bone marrow to be infiltrated by excessive fibrous connective tissue and blood vessels, leading to a hypervascular bone state. Eventually, the hypercellularity may diminish, leaving a pagetic bone, which is known as burned-out Paget disease.
Paget disease can affect every bone in the skeleton, with an affinity for the axial skeleton, long bones, and the skull. The skeletal sites primarily affected include the pelvis, lumbar spine, femur, thoracic spine, sacrum, skull, tibia, and humerus. The hands and feet are very rarely involved.
Complications of Paget disease depend on the site affected and the activity of the disease. When Paget disease occurs around a joint, secondary osteoarthritis may ensue. When the skull is involved, the patient may develop deafness, vertigo, tinnitus, dental malocclusion, basilar invagination, vertebral insufficiency, and cranial nerve involvement.
Frequently, erythema is present over the affected bone area, which is due to the increased skin temperature from the hypervascularity. Hypervascularity occurs because the abnormal woven bone pattern of pagetic bone permits the bone marrow to be infiltrated by large numbers of blood vessels. In patients with Paget disease who have extensive bony involvement, this increased bone vascularity may cause high-output cardiac failure and an increased likelihood of bleeding complications following surgery.
Vertebral involvement of Paget disease may be associated with serious complications, including nerve-root compressions and cauda equina syndrome. Fractures, which are the most common complication of Paget disease, may occur and may have potentially devastating consequences. Rarely, pagetic bone may undergo a sarcomatous transformation.
Laboratory values, including serum calcium, phosphorus, and parathyroid hormone levels, are normal in persons with Paget disease. However, hypercalcemia may complicate the course of Paget disease, most frequently in the setting of immobilization. Elevated levels of uric acid and an increased prevalence of gout have been reported in patients with Paget disease.
Levels of bone-turnover markers (including markers of bone formation and resorption) are elevated in patients with active Paget disease and may be used to monitor the course of disease. The degree of elevation of these biomarkers helps identify the extent and severity of bone turnover. Markers of bone turnover that are useful to monitor in persons with Paget disease include bone specific alkaline phosphatase (marker of bone formation), deoxypyridinoline (marker of bone resorption), and N -telopeptide of type I collagen (marker of bone resorption). Alpha-alpha type I C-telopeptide fragments are sensitive markers of bone resorption for assessing disease activity and monitoring treatment efficacy in persons with Paget disease.1 Serum osteocalcin, a marker of bone formation, is not a useful parameter to assess in persons with Paget disease. Upon successful treatment of Paget disease, the level of these bone markers is expected to decrease.
The juvenile form of Paget disease differs greatly from the adult version. Juvenile Paget disease is characterized by widespread skeletal involvement and has distinctly different histologic and radiologic features.
Paget disease is estimated to occur in 1-3% of individuals older than 45-55 years and in up to 10% in persons older than 80 years. It is estimated to affect 1 to 3 million people in the United States alone.
According to a 2000 study by Altman et al, the prevalence of pelvic Paget disease was 0.71% ±0.18% in the United States based on data from the National Health and Nutrition Examination Survey I (NHANES I, 1971-1975). The male-to-female ratio was 1.2:1, and the prevalence of pelvic Paget disease was the same in white persons and black persons. The prevalence of pelvic Paget disease increased with age, with the highest prevalence in persons older than 65 years. Geographically, pelvic Paget disease was least common in the southern United States and most common in the northeastern United States.2
The prevalence of Paget disease varies greatly among countries, with the greatest prevalence in Europe (predominantly England, France, and Germany), Australia, and New Zealand. In Europe, the incidence of Paget disease has been decreasing over the last 20 years.3 Paget disease is very rare in Asian countries, especially China, India, and Malaysia, and in the Middle East and Africa.
In Europe, the prevalence rates of Paget disease appear to decrease from north to south, with the exception of Norway and Sweden, which both have very low rates (0.3%). The highest prevalence in Europe is found in England (4.6%) and France (2.4%) in hospitalized patients older than 55 years. Other European countries, such as Ireland, Spain, Germany, Italy, and Greece, report prevalence rates of Paget disease that range from 0.5% to approximately 2%.
The prevalence rates of Paget disease in Australia and New Zealand range from 3-4%.
The prevalence of Paget disease in Sub-Sahara Africa is 0.01-0.02%, and, in Israel, Paget disease is predominantly found in Jews; however, cases have recently been reported in Israeli Arabs.
In South America, the incidence of Paget disease is relatively high in Argentina (around Buenos Aires), which was settled by Spanish and Italian immigrants, and lower in Chile and Venezuela.
Osteoarthritis
Osteoporosis
Osteomalacia (may be associated with high bone-specific alkaline phosphatase [BSAP] levels)
Malignancy with skeletal metastasis
The major histologic feature of Paget disease is abnormal bony architecture. The 3 distinct phases in Paget disease may all exist separately or in the same bone at one time. The first phase consists of osteolysis of bone, which is soon accompanied by accelerated deposition of pieces of bone in a random fashion (mixed phase). The final phase consists of accelerated osteoblastic bone formation with an increase in the number and activity of the osteoblasts. This results in increased osteoid volume and replacement of the normal marrow with fibrous tissue.
Orthopedic surgeons, neurosurgeons, physical therapists, and oncologists may play useful adjunctive roles in the management of Paget disease.
No specific dietary modifications are necessary in patients with Paget disease. However, in patients with Paget disease who are receiving bisphosphonate therapy, ensure adequate intake of calcium and vitamin D.
No specific adjustments in physical activity levels are necessary in patients with Paget disease. If secondary osteoarthritis occurs in the knee, quadriceps-strengthening exercises may be helpful. If bone pain occurs with weight bearing or if gait abnormalities are present, individualized adjustment in physical activity regimens may be necessary.
Treatment with bisphosphonates should be considered first-line therapy in patients with Paget disease. Note that osteonecrosis of the jaw has recently been described in patients taking bisphosphonates and this should be discussed with patients before initiating treatment, when possible.10
These agents are analogs of pyrophosphate and act by binding to hydroxyapatite in bone matrix, thereby inhibiting the dissolution of crystals. They prevent osteoclast attachment to the bone matrix and osteoclast recruitment and viability.
Principally acts by inhibiting osteoclastic bone resorption. Recommended for treatment of Paget disease.
40 mg/d PO for 6 mo
Not established; not recommended for use in pediatric patients
None reported
Documented hypersensitivity; hypocalcemia, esophageal stricture or dysmotility; severe renal insufficiency (CrCl <35 mL/min); inability to stand or sit upright for 30 min after administration
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Must be taken at least 30 min before first food, beverage, or medication of the day and should be taken with large amounts of water; rare (post-marketing) occurrences of gastric and duodenal ulcers reported; caution in renal impairment (not recommended with CrCl <35 mL/min); osteonecrosis of jaw has been reported
Principally acts by inhibiting osteoclastic bone resorption. Recommended to treat Paget disease.
Approved regimen is 30 mg IV over 4 h on 3 consecutive days in 500 mL of sterile 0.45% or 0.9% sodium chloride; other dosing regimens including 60-90 mg pamidronate IV in 500 mL 0.45% or 0.9% saline over 2-4 h have been used
Not established; not recommended for use in pediatric patients
None reported
Documented hypersensitivity; hypocalcemia; renal impairment with serum creatinine >5 mg/dL
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Monitor hypercalcemia-related parameters (eg, serum levels of calcium, phosphate, magnesium, potassium); maintain adequate intake of calcium and vitamin D to prevent severe hypocalcemia; caution if active upper GI problems; adverse effects include nausea and diarrhea (uncommon); not recommended with CrCl <30 mL/min; osteonecrosis of the jaw has been reported
Principally acts by inhibiting osteoclastic bone resorption. Recommended to treat Paget disease.
30 mg/d PO for 2 mo
Not established; use in pediatric patients not recommended
None reported
Documented hypersensitivity, hypocalcemia; severe renal insufficiency (CrCl <30 mL/min); inability to stand or sit upright for ≥30 min after administration
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Maintain adequate intake of calcium and vitamin D to prevent severe hypocalcemia; caution if active upper GI problems; adverse effects include nausea and diarrhea (uncommon); not recommended with CrCl <30 mL/min; osteonecrosis of the jaw has been reported
Principally acts by inhibiting bone resorption. Least potent of currently available bisphosphonate drugs.
5 mg/kg/d PO for 6 mo followed by at least 6 mo of no treatment; dose limited because drug may impair mineralization
Not established; not recommended for use in pediatric patients
Increase in PT reported when concomitantly administered with warfarin; avoid food within 2 h of administration
Documented hypersensitivity; osteomalacia; advancing lytic change in a weight-bearing bone; delayed gastric emptying; renal disease with GFR <35 mL/min
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Monitor hypercalcemia-related parameters (eg, serum levels of calcium, phosphate, magnesium, potassium); maintain adequate intake of calcium and vitamin D to prevent severe hypocalcemia; caution if active upper GI problems; adverse effects include nausea and diarrhea (uncommon); not recommended with CrCl <30 mL/min
Principally acts by inhibiting osteoclastic bone resorption.
400 mg PO qd for 3 mo
Not established; not recommended for use in pediatric patients
Do not take with food or beverages other than water; wait at least 2 h before eating or drinking beverages other than water or taking indomethacin
Documented hypersensitivity or CrCl <30 mL/min
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Monitor calcium levels; maintain adequate intake of calcium and vitamin D to prevent severe hypocalcemia; caution if active upper GI problems; adverse effects include nausea and diarrhea (uncommon); not recommended with CrCl <30 mL/min; may cause gastric irritation
Inhibits bone resorption. Inhibits osteoclastic activity and induces osteoclast apoptosis.
5 mg IV once; infuse over minimum 15 min
requires monitoring of creatinine and calcium levels prior to infusion
Not established
Concurrent administration with loop diuretics or aminoglycosides may increase risk of hypocalcemia
Documented hypersensitivity; hypocalcemia; CrCl <35 mL/min
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Caution in renal insufficiency (do not use if CrCl <35 mL/min); flulike syndrome (fever, arthralgias, myalgias, skeletal pain); severe muscle pain and electrolyte and mineral disturbances, such as low levels of serum calcium may occur; osteonecrosis of the jaw has been reported
These agents directly inhibit osteoclastic bone resorption.
Recommended for treatment of Paget disease if bisphosphonates are contraindicated. Inhibits osteoclastic bone resorption.
100 U/d SC qd; dose of 50-100 U SC 3 times/wk for 6-18 mo has also been used
Not established
None reported
Documented hypersensitivity
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Perform skin test prior to administering salmon calcitonin injection; have epinephrine available to treat anaphylaxis; hypocalcemia and nausea may occur; urinary frequency has been reported
Inpatient care may be useful for surgical complications of Paget disease.
Response to therapy is indicated by reduction of symptoms and decreases in BSAP (bone formation marker) and deoxypyridinoline, C-telopeptide,1 or N -telopeptide (bone resorption markers) levels.
No preventive measures for Paget disease are known.
Complications of Paget disease include deafness, spinal stenosis, stroke, vascular steal syndrome, congestive heart failure, fractures, osteoarthritis, sarcomas, nephrocalcinosis, and the development of bone tumors (principally sarcomas).
Many reports have described long-term remissions following successful treatment of Paget disease. However, if sarcomas arise in the setting of Paget disease, the prognosis is dismal and most patients die within 1-3 years of diagnosis.
Proper patient education on the nature of Paget disease is essential. The Paget Foundation for Paget's Disease of Bone and Related Disorders can provide useful information for patients. Call (800) 23-Paget (ie, [800] 237-2438).
Careful follow-up of patients with Paget disease is indicated for life. Periodic monitoring of bone marker levels (every 3-6 mo in those without active disease) is recommended.
Family members should be informed of the increased incidence of Paget disease in family members of the affected patient.
Alexandersen P, Peris P, Guanabens N, et al. Non-isomerized C-telopeptide fragments are highly sensitive markers for monitoring disease activity and treatment efficacy in Paget's disease of bone. J Bone Miner Res. Apr 2005;20(4):588-95. [Medline].
Altman RD, Bloch DA, Hochberg MC, et al. Prevalence of pelvic Paget's disease of bone in the United States. J Bone Miner Res. Mar 2000;15(3):461-5. [Medline].
Poor G, Donath J, Fornet B, et al. Epidemiology of Paget's disease in Europe: the prevalence is decreasing. J Bone Miner Res. Oct 2006;21(10):1545-9. [Medline].
Hughes AE, Shearman AM, Weber JL, et al. Genetic linkage of familial expansile osteolysis to chromosome 18q. Hum Mol Genet. Feb 1994;3(2):359-61. [Medline].
Neale SD, Schulze E, Smith R, et al. The influence of serum cytokines and growth factors on osteoclast formation in Paget's disease. QJM. Apr 2002;95(4):233-40. [Medline].
Hoyland JA, Freemont AJ, Sharpe PT. Interleukin-6, IL-6 receptor, and IL-6 nuclear factor gene expression in Paget's disease. J Bone Miner Res. Jan 1994;9(1):75-80. [Medline].
Schweitzer DH, Oostendorp-van de Ruit M, Van der Pluijm G, et al. Interleukin-6 and the acute phase response during treatment of patients with Paget's disease with the nitrogen-containing bisphosphonate dimethylaminohydroxypropylidene bisphosphonate. J Bone Miner Res. Jun 1995;10(6):956-62. [Medline].
Menaa C, Barsony J, Reddy SV, et al. 1,25-Dihydroxyvitamin D3 hypersensitivity of osteoclast precursors from patients with Paget's disease. J Bone Miner Res. Feb 2000;15(2):228-36. [Medline].
Hoyland J, Sharpe PT. Upregulation of c-fos protooncogene expression in pagetic osteoclasts. J Bone Miner Res. Aug 1994;9(8):1191-4. [Medline].
Ruggiero SL, Mehrotra B, Rosenberg TJ, et al. Osteonecrosis of the jaws associated with the use of bisphosphonates: a review of 63 cases. J Oral Maxillofac Surg. May 2004;62(5):527-34. [Medline].
Alvarez L, Guanabens N, Peris P, et al. Discriminative value of biochemical markers of bone turnover in assessing the activity of Paget's disease. J Bone Miner Res. Mar 1995;10(3):458-65. [Medline].
Alvarez L, Guanabens N, Peris P, et al. Usefulness of biochemical markers of bone turnover in assessing response to the treatment of Paget's disease. Bone. Nov 2001;29(5):447-52. [Medline].
Ankrom MA, Shapiro JR. Paget's disease of bone (osteitis deformans). J Am Geriatr Soc. Aug 1998;46(8):1025-33. [Medline].
Delmas PD, Meunier PJ. The management of Paget's disease of bone. N Engl J Med. Feb 20 1997;336(8):558-66. [Medline].
Favus MJ, ed. Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism. 4th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 1999.
Hadjipavlou AG, Gaitanis LN, Katonis PG, et al. Paget's disease of the spine and its management. Eur Spine J. Oct 2001;10(5):370-84. [Medline].
Harrington KD. Surgical management of neoplastic complications of Paget's disease. J Bone Miner Res. Oct 1999;14 Suppl 2:45-8. [Medline].
Holgado S, Rotes D, Guma M, et al. Paget's disease of bone in early adult life. Ann Rheum Dis. Feb 2005;64(2):306-8. [Medline].
Kaplan FS. Surgical management of Paget's disease. J Bone Miner Res. Oct 1999;14 Suppl 2:34-8. [Medline].
Kaplan FS, Singer FR. Paget's Disease of Bone: Pathophysiology, Diagnosis, and Management. J Am Acad Orthop Surg. Nov 1995;3(6):336-344. [Medline].
Khan SA, Brennan P, Newman J, et al. Paget's disease of bone and unvaccinated dogs. Bone. Jul 1996;19(1):47-50. [Medline].
Klippel JH, ed. Primer on the Rheumatic Diseases. 12th ed. Atlanta, Ga: Arthritis Foundation; 2001.
Leach RJ, Singer FR, Cody JD, et al. Variable disease severity associated with a Paget's disease predisposition gene. J Bone Miner Res. Oct 1999;14 Suppl 2:17-20. [Medline].
Leach RJ, Singer FR, Roodman GD. The genetics of Paget's disease of the bone. J Clin Endocrinol Metab. Jan 2001;86(1):24-8. [Medline].
Lopez-Abente G, Morales-Piga A, Elena-Ibanez A, et al. Cattle, pets, and Paget's disease of bone. Epidemiology. May 1997;8(3):247-51. [Medline].
Lyles KW, Siris ES, Singer FR, et al. A clinical approach to diagnosis and management of Paget's disease of bone. J Bone Miner Res. Aug 2001;16(8):1379-87. [Medline].
Noor M, Shoback D. Paget's disease of bone: diagnosis and treatment update. Curr Rheumatol Rep. Feb 2000;2(1):67-73. [Medline].
Ooi CG, Fraser WD. Paget's disease of bone. Postgrad Med J. Feb 1997;73(856):69-74. [Medline].
Perry HM III, Kraezle D, Miller DK. Paget's disease in African Americans. Clin Geriatr. 1995;3:6974.
Reddy SV, Kurihara N, Menaa C, et al. Paget's disease of bone: a disease of the osteoclast. Rev Endocr Metab Disord. Apr 2001;2(2):195-201. [Medline].
Reddy SV, Menaa C, Singer FR, et al. Cell biology of Paget's disease. J Bone Miner Res. Oct 1999;14 Suppl 2:3-8. [Medline].
Roodman GD. Osteoclast function in Paget's disease and multiple myeloma. Bone. Aug 1995;17(2 Suppl):57S-61S. [Medline].
Roodman GD. Paget's disease and osteoclast biology. Bone. Sep 1996;19(3):209-12. [Medline].
Roodman GD, Kurihara N, Ohsaki Y, et al. Interleukin 6. A potential autocrine/paracrine factor in Paget's disease of bone. J Clin Invest. Jan 1992;89(1):46-52. [Medline].
Schneider D, Hofmann MT, Peterson JA. Diagnosis and treatment of Paget's disease of bone. Am Fam Physician. May 15 2002;65(10):2069-72. [Medline].
Wermers RA, Tiegs RD, Atkinson EJ, et al. Morbidity and Mortality Associated with Paget's Disease of Bone: A Population-based Study. J Bone Miner Res. Feb 12 2008;[Medline].
Paget disease, Paget's disease, osteitis deformans, monostotic Paget disease, multifocal Paget disease, monostotic Paget’s disease, multifocal Paget’s disease, burned-out Paget disease, burned-out Paget’ disease, osteoporosis circumscripta, bone disorder, bone disease, woven bone, pagetic bone, bone inflammation, chronic bone inflammation, bone remodeling
Laura D Carbone, MD, MS, Professor of Medicine, Division of Connective Health Diseases, Director, Memphis Metabolic Bone Center, Department of Medicine, University of Tennessee Health Science Center College of Medicine
Laura D Carbone, MD, MS is a member of the following medical societies: Alpha Omega Alpha, American College of Rheumatology, American Medical Women's Association, American Society for Bone and Mineral Research, and International Society for Clinical Densitometry
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Kristine M Lohr, MD, MS, Program Director, Professor, Department of Internal Medicine, Division of Rheumatology and Women's Health, University of Kentucky School of Medicine
Kristine M Lohr, MD, MS is a member of the following medical societies: American College of Physicians, American College of Rheumatology, and American Medical Women's Association
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Marlon J Navarro, MD, Fellow, Department of Rheumatology, University of Tennessee at Memphis
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Elliot Goldberg, MD, Dean of the Western Pennsylvania Clinical Campus, Professor, Department of Medicine, Temple University School of Medicine
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Alex J Mechaber, MD, FACP, Associate Dean for Undergraduate Medical Education, Associate Professor of Medicine, University of Miami Miller School of Medicine
Alex J Mechaber, MD, FACP is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, and Society of General Internal Medicine
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Herbert S Diamond, MD, Professor of Medicine, Temple University School of Medicine; Chairman Emeritus, Department of Internal Medicine, Western Pennsylvania Hospital
Herbert S Diamond, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American College of Rheumatology, American Medical Association, and Phi Beta Kappa
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