Whole body retention of Tc-99m phosphate in Paget's disease of bone

The effectiveness of the 24-hour whole body retention of Tc-99m MDP in monitoring disease activity was evaluated in 58 patients with Paget's disease of bone. Patients had baseline 24-hour retention studies, bone scans, radionuclide bone blood-flow studies, and alkaline phosphatase and OH-Proline level measurements. Increased retention of Tc-99m MDP was present in 88% (51/58) of individuals while alkaline phosphatase and OH-Proline were respectively elevated in 100% (58/58) and 64% (35/55) of patients. Forty-seven examinations were further obtained to evaluate changes in retention with therapy. Retention correctly reflected response to treatment in 89.3% of follow-ups versus 85.1% with alkaline phosphatase (n = 47). It was accurate in 90.9% of patients versus 75% for OH-Proline (n = 44). We conclude that the retention study, while not absolutely correlative with Pagetic activity, still is useful in grading the condition. It is a simple additional step that monitors the global severity of lesions localized on bone scans.