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Journal of the American Society of Nephrology, Vol 2, 1136-1143, Copyright © 1991 by American Society of Nephrology
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AJ Felsenfeld, D Ross and M Rodriguez
Department of Medicine, Wadsworth VA Medical Center, Los Angeles, CA 90073.
During the study of parathyroid function in 19 hemodialysis patients with low turnover aluminum bone disease, it was observed that serum parathyroid hormone (PTH) levels were higher during the induction of hypocalcemia than during the recovery from hypocalcemia. This type of PTH response has been termed hysteresis. Hypocalcemia was induced during hemodialysis with a calcium-free dialysate. When the total serum calcium level decreased to 7 mg/dL, the dialysate calcium concentration was changed to 3.5 mEq/L and the dialysis session was completed. One week later, hypercalcemia was induced during hemodialysis with a high- calcium dialysate. The mean basal PTH level was 132 +/- 37 pg/mL (normal, 10 to 65 pg/mL; immunoradiometric (IRMA), Nichols Institute, San Juan Capistrano, CA) and increased to a maximal PTH level of 387 +/- 91 pg/mL during hypocalcemia. For the same ionized calcium concentration, the PTH level was higher during the induction of hypocalcemia than during the recovery from hypocalcemia. Conversely, for the same ionized calcium concentration, the PTH level was greater when hypercalcemia was induced from the nadir of hypocalcemia than when hypercalcemia was induced from basal serum calcium. The set point of calcium (defined as the serum calcium concentration required to reduce maximal PTH by 50%) was greater during the induction of hypocalcemia than during the recovery from hypocalcemia (4.44 +/- 0.10 versus 4.25 +/- 0.09 mg/dL; P = 0.03). The mean basal ionized calcium concentration and the mean ionized calcium concentration at the intersection of the two PTH-calcium curves were the same (4.61 +/- 0.13 versus 4.61 +/- 0.12 mg/dL).(ABSTRACT TRUNCATED AT 250 WORDS)
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A. J. Felsenfeld, M. Rodriguez, and E. Aguilera-Tejero Dynamics of Parathyroid Hormone Secretion in Health and Secondary Hyperparathyroidism Clin. J. Am. Soc. Nephrol., November 1, 2007; 2(6): 1283 - 1305. [Abstract] [Full Text] [PDF] |
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H. Cardinal, J.-H. Brossard, L. Roy, R. Lepage, L. Rousseau, and P. DAmour The Set Point of Parathyroid Hormone Stimulation by Calcium Is Normal in Progressive Renal Failure J. Clin. Endocrinol. Metab., November 1, 1998; 83(11): 3839 - 3844. [Abstract] [Full Text] |
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