Paget's disease is not often diagnosed in people less than 40 years of age. Women are more commonly affected than men. Prevalence of Paget's disease ranges from 1.5 to 8.0 percent, depending on age and country of residence. Prevalance of familial Paget's disease (where more than one family member has the disease) ranges from 10 to 40 percent in different parts of the world. Because early diagnosis and treatment is important, after age 40, siblings and children of someone with Paget's disease may wish to have an alkaline phosphatase blood test every two or three years. If the alkaline phosphatase level is abnormal, other tests such as a bone-specific alkaline phosphatase test, bone scan, or X-ray can be performed.