Clinical evaluation of patients showing renal hyperconcentration of Tc-99m pyrophosphate (hot kidneys sign) on bone scintigraphy

We evaluated clinical and follow up findings for 59 patients I whom diffuse increased uptake of Tc-99m pyrophosphate in both renal parenchyma (”hot kidney sign”) had been noted on bone scintigraphy. In more than half the patients, the cause of hyperconcentration was the administration antitumor drugs. The period during which antitumor drugs affect renal uptake is thought to exceed that reported previously in the literature. In most patients, standard laboratory test results did not show and values indicative of renal dysfunction, and thus, in most cases ”hot kidneys sign” apparently reflects subclinical and transient renal dameges. However, it was noted that patients with more increased uptake. Moreover, post-scintigraphy follow-up study revealed tha 4 (20%) of 20 patients with ”hot kidbeys sign” subsequently developed more severe renal dysfunction, and two patients died due to renal failure. We therefore recommened that the renal function of patients who show ”hot kidneys sign” is montiored and followed up. Tc-99m-IMDP renograms of patients with ”hot kidneys sign” showed smaller slope angle of both up- and down-slope than did that of controls. Tc-99m-HMDP renograns may be useful in the quantitative evaluation of renal function.