strontium-radioisotopes and Kidney-Failure--Chronic

To assess directly the effect of ionic dissociation on the bioavailability of calcium, we used the double isotope inverse convolution method to compare the absorption of calcium gluconate and calcium pyrrolidone carboxylate, an organic, highly dissociated salt. Two tests were performed at a 2 day interval, using in random sequence either salt as a carrier. Forty-eight subjects of various age and clinical condition were studied. The use of the more dissociated salt consistently and significantly increased fractional absorption in a rather constant ratio. Moreover, it slowed absorption in normal subjects whatever their age, and accelerated it in patients with chronic renal failure or osteoporosis, leading to inferences on the alteration of calcium absorption in these conditions.

Topics: Adult; Aged; Aging; Biological Availability; Calcium Gluconate; Calcium Radioisotopes; Female; Gluconates; Humans; Intestinal Absorption; Kidney Failure, Chronic; Kinetics; Male; Middle Aged; Osteoporosis; Pyrrolidinones; Pyrrolidonecarboxylic Acid; Strontium Radioisotopes

1. Stable strontium (Sr) has been proposed as an alternative to calcium (Ca) isotopes for the measurement of intestinal Ca absorption. The aim of this study was to compare the time course and fractional absorption of Ca and Sr, when both are measured using dual-tracer techniques. 2. 45Ca and Sr absorption tests were carried out on consecutive days in patients with osteoporosis (n = 10) or chronic renal failure (n = 7). Both tests were repeated in four patients with chronic renal failure after treatment with calcitriol (1 microgram daily for 10 days). 3. The time course of Ca absorption was determined using the 85Sr (intravenous)/45Ca (oral) dual-tracer technique, and the time course of Sr absorption using 85Sr (intravenous)/stable Sr (oral). Oral tracers were administered on consecutive days with a test meal containing 5.3 mmol of Ca and 2.5 mmol of either stable Sr or Ca carrier. The fractional absorption of 45Ca and Sr at 6h (FA360) and the absorption rate as a function of time were calculated by deconvolution. 4. The mean FA360 for Sr (20.2%) was lower than the mean FA360 for 45Ca (37.8%, P < 0.001, paired t-test), but the time course of Sr absorption was similar to that of Ca. There was a significant correlation between the FA360 for 45Ca and Sr, although the relationship was improved by including a quadratic term (R2 = 0.89, P < 0.001, significance of quadratic term, P < 0.05). After 1,25-dihydroxyvitamin D treatment, the FA360 of stable Sr increased 4.29-fold, whereas the FA360 of 45Ca increased only 2.4-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Aged; Calcitriol; Calcium; Calcium Radioisotopes; Female; Humans; Intestinal Absorption; Kidney Failure, Chronic; Male; Middle Aged; Osteoporosis, Postmenopausal; Strontium; Strontium Radioisotopes; Time Factors

Bone metabolism studies were performed in 44 subjects with and without bone disease using a calcium tracers kinetics model, the central feature of which is an expanding exchangeable calcium pool. In normal subjects the accretion rate and the exchangeable calcium pool ranged from 1.49 to 8.45 (mean 3.9 +/- 2.05) mg.d-1kg-1 and from 60 to 131 (mean 81.25 +/- 18.11) mg.kg-1, respectively. The patients with osteogenesis imperfecta. Pierre Marie's disease and one out of two cases of hypoparathyroidism had values which fell within the normal range. Both the accretion rate and the exchangeable calcium pool were significantly elevated in patients with Paget's disease and with hyperparathyroidism. Uremic patients with generalized bone lesions had accretion rates or both parameters elevated. As far as patients with successful renal transplant are concerned, the results suggest that this method is a very poor means for detecting bone disorders with only focal lesions. In contrast, the method can be very useful when persistent renal osteodystrophy or secondary hyperparathyroidism are suspected.

Topics: Adult; Aged; Bone and Bones; Bone Diseases; Calcium; Chronic Kidney Disease-Mineral and Bone Disorder; Female; Humans; Hyperparathyroidism; Hypoparathyroidism; Kidney Failure, Chronic; Kidney Transplantation; Male; Middle Aged; Osteitis Deformans; Osteoarthropathy, Secondary Hypertrophic; Osteogenesis Imperfecta; Renal Dialysis; Strontium Radioisotopes

The immunosuppressive effect of extracorporeal irradiation of the blood (ECIB) using small transit doses (TD) over a long time period was studied. The blood of 15 uremic patients undergoing hemodialysis in preparation for kidney transplantation was treated with15-, 25-, or 41-rad TDs for a total of 150 h, using the beta-emitting radioisotope 90Sr-90Y. The number of blood volumes (BV) irradiated ranged from 159 to 265. The irradiation resulted in selective lymphocytopenia, but the effect on the immune response of lymphocytes, as measured in vitro with lymphocyte transformation tests, varied. Six kidney transplantations were performed resulting in rejection in two cases, one which was easily reversed and one with many rejection episodes, ending in death. Thus treatment with small TDs over long periods can reduce lymphocyte counts, but any subsequent immunosuppressive effect is uncertain. Our results do not support the hypothesis that such irradiation can influence the immune response of lymphocytes without destroying the cells.

Topics: Adult; Aged; Blood; Female; Humans; Kidney Failure, Chronic; Kidney Transplantation; Leukocyte Count; Lymphocyte Activation; Lymphocyte Depletion; Lymphocytes; Male; Middle Aged; Radiation Dosage; Radiation Effects; Renal Dialysis; Strontium Radioisotopes; Transplantation, Homologous; Yttrium Radioisotopes