Measurement of 24-hour whole-body retention of Tc-99mMDP with a thyroid uptake probe: quantitative assessment of metabolic and metastatic bone diseases.

A new method for the measurement of 24-hour whole-body retention (WBR) of Tc-99mMDP, using a thyroid uptake probe with a normal scintigraphic dose was established. Its clinical significance was evaluated in 106 subjects over 20 years old with various bone disorders, including metabolic and metastatic bone diseases. Reproducibility of 24-hour WBR in 10 patients was very good (y = x - 0.3, r = 0.996). The 24-hour WBR of Tc-99mMDP in healthy subjects was 30.4% +/- 4.6%. The WBR values for patients with chronic renal failure, metastatic bone disease, osteomalacia and hyperthyroidism were 98.4% +/- 3.0%, 44.0% +/- 8.0%, 50.7% +/- 2.8% and 39.4% +/- 6.5%, respectively, which were significantly higher when compared with the healthy group. However the WBR of the steroid-induced osteoporotic group was significantly lower (17.3% +/- 5.4%), suggesting the possibility of being able to differentiate osteoporotic patients from healthy subjects. For assessment of the value of 24-hour WBR, simultaneous bone imaging was essential so as to be able to exclude the effects of arthropathy and/or fracture, which were often found in the older age group.