Skeletal blood flow in Paget's disease of bone

Using a modified plasma clearance technique, with 18F as a tracer, it is possible to measure blood flow to bone in man. In the normal adult skeleton, blood flow amounts to about 300 ml/min. In untreated Paget's disease of bone there is a striking increase, which is proportional to the biochemical severity of the disease : total blood flow to the skeleton is approximately doubled at an alkaline phosphatase of 50 KAu/dl (i.e. about four times the normal upper limit). Treatment with calcitonin brings a rapid return to normal, possibly before there is a detectable biochemical response. This may explain the rapid pain relief often reported on starting treatment with calcitonin.