High renal activity on bone scintigrams. A sign of hypercalcaemia?

Various abnormalities of the renal tract can be detected from the renal images seen on 99Tcm methylene diphosphonate (MDP) bone scintigrams. Diffusely increased renal parenchymal activity has been associated with cytotoxic and other drug therapy, radiation nephritis, iron overload and cirrhosis. A further association--with hypercalcaemia--is reported here. In a retrospective study, 1950 bone scintigrams were reviewed and a significant relationship between high renal activity and hypercalcaemia was found. This was subsequently confirmed by a small prospective study. None of the patients whose bone scintigrams showed this association had evidence of nephrocalcinosis on X rays. It is postulated that in these hypercalcaemic patients there may be high tissue calcium in the kidneys which results in the high uptake of MDP, and it is suggested that serum calcium be measured in patients with previously unsuspected hypercalcaemia whose bone scintigrams exhibit the finding of high parenchymal renal activity.