The bone scan may be of value in the assessment of patients with metabolic bone disease. However the superiority of the bone scan when compared to radiology in conditions such as renal osteodystrophy, osteomalacia, primary hyperparathyroidism, and osteoporosis requires substantiation with the newer radiopharmaceuticals which have a higher affinity for bone. Two methods of quantitating skeletal uptake of tracer have been assessed to try to remove the subjective aspect of bone scan evaluation. Measurements of bone to soft tissue ratios have proved clinically disappointing, but 24 hour whole body retention of diphosphonate appears to provide a sensitive index of increased bone turnover.