Many patients who have Pagetís disease of bone do not know that they
have it, since the disease may be so mild that it is not detected. Sometimes,
the patientís doctor is alerted to the possibility of Pagetís disease when a
blood test reveals an elevated level of serum alkaline phosphatase (SAP).† Sometimes the patientís symptoms are
confused with arthritis or other disorders. In other cases, the diagnosis is
made only after complications have developed.
Q. What is SAP?
is a chemical (enzyme) that is produced by bone cells and is over-produced by
Pagetic bone. SAP is measured by using a routine blood test.† A SAP level that is higher than normal,
provided that there is no evidence of liver disease, probably indicates that
the source of elevated SAP is bone rather than some other part of the
body.† A mild increase in SAP level (up
to twice the normal level) might indicate Pagetís disease or another problem,
such as a healing fracture.† A SAP level
two or more times higher than normal strongly suggests Pagetís disease,
especially if serum calcium and phosphorus, as well as renal (kidney) function,
The range of SAP that is considered normal varies
considerably depending on the laboratory used for the test. A typical ďnormalĒ
range for a person over the age of 60 may range from 20-120 units.
In addition to its use in diagnosis, measurement of SAP
is an important tool for monitoring a patientís response to therapy for Pagetís
disease. In some patients it may be necessary to measure the serum bone alkaline phosphatase, using a
special test which is helpful in assessing bone disease in patients with
abnormal liver function. In some cases urinary markers of bone resorption such
as N-telopeptide are also used to monitor the response the treatment.
Q. What is a bone scan and how is it used to diagnose Pagetís disease?
A. A bone scan is another way to
identify bones affected by Pagetís disease. When a bone scan is performed, a
safe amount of a radioactive substance is injected and circulates through the
bloodstream, showing areas of the skeleton where Pagetís disease might be
Q. How are X-rays used to diagnose Pagetís disease?
X-rays are used alone or in conjunction with bone scans to confirm or eliminate
the presence of Pagetís disease. Bones affected by Pagetís disease have a
characteristic appearance on x-rays.
Q. When may a bone biopsy be used to diagnose Pagetís disease?
a bone biopsy may be required if the x-ray is not conclusive.
factors for diagnosing Pagetís disease are an elevated SAP and an x-ray showing
For additional information,
The Paget Foundation
120 Wall Street, Suite 1602
New York, NY 10005-4001
Tel (800) 23-Paget or (212) 509-5335
Fax (212) 509-8492