EFFECTS OF PARATHYROID-HORMONE DEPLETION IN DOGS WITH INDUCED RENAL-FAILURE

Six parathyroidectomized (PTX) and 6 control dogs had renal mass reduc ed by 15/16, and were studied for effects of parathyroid hormone deple tion on progression of renal failure. All PTX dogs and 4 of 6 control dogs survived until necropsy after 32 weeks. Plasma parathyroid hormon e concentration was undetectable in p?X dogs throughout the study, but was greater than normal in control dogs. Serum inorganic phosphate (P ) concentration was increased in PTX dogs (6.8 +/- 0.1 mg/dl) and in c ontrol dogs (7.5 +/- 0.2), but did not differ significantly (P = 0.254 ) bem een groups. Ionized blood calcium values (Ca2+) were significant ly (P = 0.014) lower in PTX dogs (1.31 +/- 0.01 mmol/L) than in contro l dogs (1.36 +/- 0.00 mmol/L), but were more variable in PTX dogs. Val ues in PTX dogs were not significantly different from those in control dogs for glomerular filtration rate (P = 0.914), plasma creatinine co ncentration (P = 0.903), and urine protein to creatinine ratio (P = 0. 756) determined at intervals during the study. Terminal glucose tolera nce and plasma insulin concentrations, P tolerance, and renal P excret ion did not differ between groups. Histologic comparison of kidneys re moved during reduction of renal mass with kidneys removed at necropsy revealed development of lesions in both groups of dogs, and no protect ive effect from parathyroidectomy. Mineral analysis of aorta, brain, h eart, lungs, and skeletal muscle obtained at necropsy revealed no sign ificant difference between PTX and control groups. Renal cortical calc ium concentration was significantly (P < 0.05) greater in kidneys obta ined at necropsy than in kidneys obtained during nephrectomy, but PTX did not protect renal cortex from calcium deposition.