title: Changes in renal uptake of Tc-99m methylene diphosphonate (MDP) in stone-forming rats.
abstract: A pyridoxine (vitamin B6)-deficient diet in rats was used as a model of early renal lithiasis to find out if "stone-formers" could be identified from control animals by differences in the biodistribution of Tc-99m MDP. The mean renal uptake of this agent at 3 hours was about 70% higher in test animals than in controls, but there was considerable overlap between the upper limits of the normal range and lower values in "stone-formers." If these results were valid for humans, the metabolic abnormality in males with early stone-forming disease could not be identified with certainty by in vivo measurements of Tc-99m MDP renal uptake alone. However, the skeletal uptake of MDP in the "stone-forming" animals was depressed by 28 to 35%, compared with control rats. Consequently, the renal to skeletal MDP concentration ratio was invariably elevated in "stone-formers" beyond the 95 percentile normal range. Unexpectedly, 76% of the pyridoxine-deficient animals had a higher accumulation of MDP in the myocardium than the upper limit of the normal range. The pyridoxine-deficient diet induced no remarkable early changes in the biodistribution or renal clearance of I-131 Hippuran.
mesh_terms: D000818:Animals; D004164:Diphosphonates / Q000378:metabolism; D004195:Disease Models, Animal; D007668:Kidney / Q000378:metabolism*; D007669:Kidney Calculi / Q000000981:diagnostic imaging* / Q000209:etiology / Q000378:metabolism; D008297:Male; D011877:Radionuclide Imaging; D051381:Rats; D011919:Rats, Inbred Strains; D013667:Technetium / Q000378:metabolism; D013669:Technetium Tc 99m Medronate; D026681:Vitamin B 6 Deficiency / Q000150:complications*
chemical_list: D004164:Diphosphonates; D013667:Technetium; D013669:Technetium Tc 99m Medronate