A Brief Discussion On Paget’s disease

Paget’s disease is the disease of the bone caused by a high bone turnover and disorganized osteoid formation. Involved bone is deformed and weak.

How common is paget’s disease
Radiographic evidence is seen in around 2.5% of men over 55 years of age and a little less in women. Less than 10% of those have symptoms. It occurs predominately in people of English origin, including those in North America and Australia. It may be declining in prevalence.

Pathology of bone in paget’s disease.
Paget’s disease is caused by focal or multifocal areas of bone resorption by large osteoclasts, followed by increased bone formation, but the new bone is abnormal with a mosaic appearance on microscopy. It is expanded in size, deforms and fractures more easily and is highly vascularised.

Serum and urine biochemical changes seen in paget’s disease

• Raised alkaline phosphatase.
• Raised serum osteocalcin ( not routinely used )
• Raised urinary hydroxyproline and pyridinolone.

Some other causes of raised alkaline phospahtase

• Hyperparathyroidism
• Bone metastases
• Growth
• Osteomalacia
• Liver disease

Other investigation that may be useful in paget’s disease
Radiology confirms Paget’s disease by bone expansion. This is rare in metastasis which tend to be sclerotic but expanded. Uncertainty is occasionally resolved by bone biopsy, for example in case of isolated rib expansion.

Indications for treatment

• Bone pain or hypercalcemia that tends to occur only in immobilized patients are the usual indications.

Should asymptomatic paget’s disease be treated?
There is no absolute consensus, but indications include :

• Skull disease ( risk of deafness )
• Long bone disease ( risk of deformity, fracture and arthritis )
• Spinal disease ( risk of cord compression or vascular steel syndrome )

Current treatment of choice
Bisphosphonate therapy ( intravenous pamidronate, oral risedronate or intravenous zolendronic acid ) is the treatment of choice with a view to normalization of alkaline phospahatase levels ( achieved in around 75% of patients ) ; this is also associated with marked pain reduction.