Isotopic bone mineralization rates in maintenance dialysis patients

The expanding pool model of radiocalcium kinetics has been used in 13 maintenance dialysis patients to measure bone mineralization rate. No difficulties were met in applying the data to the model, and values for the bone mineralization rate ranged from 0.0 to 2.0 mmol/kg Ca++ per day. The bone histology obtained at the time of the study showed a correlation between the degree of secondary hyperparathyroidism and the bone mineralization rate, with low values of the latter occurring in atypical osteomalacia (two patients) or inactive-looking bone (one patient) and raised values in seven patients. The plasma alkaline phosphatase and immunoassayable parathyroid hormone levels each correlated significantly with the bone mineralization rate. These findings suggest that the technique is valid when applied to hemodialysis patients and provides quantitative information about skeletal calcium metabolism in different types of renal bone disease.