Journal of Clinical Endocrinology & Metabolism, Vol 80, 3458-3464, Copyright © 1995 by Endocrine Society

ARTICLES

Mechanism of renal calcium conservation with estrogen replacement therapy in women in early postmenopause--a clinical research center study

WR McKane, S Khosla, MF Burritt, PC Kao, DM Wilson, SJ Ory and BL Riggs
Division of Endocrinology and Metabolism, Mayo Clinic, Rochester, Minnesota 55905, USA.

To assess the mechanism by which estrogen replacement therapy (ERT) enhances renal calcium conservation in perimenopausal women, we studied 18 normal women in early postmenopause before and after 6 months of ERT (cyclic treatment with transdermal estradiol at 100 micrograms/day and medroxyprogesterone acetate at 10 mg/day for the first 12 days of each cycle). The changes after ERT were: serum ionized calcium and ultrafiltrable calcium, no change; serum intact PTH, 38.2% increase (P < 0.0001); serum 1,25-dihydroxyvitamin D, 23.8% increase (P < 0.0001); urinary calcium excretion, 33.3% decrease (P < 0.001); and deoxypyridinoline (a marker for bone resorption), 19.5% decrease (P < 0.0001). Also, ERT increased tubular reabsorption of calcium (TRCa; 97.6% +/- 0.2% to 98.7% +/- 0.1%; P < 0.0001), and this increase correlated with that in serum PTH (r = 0.49; P < 0.05). After the infusion of human PTH-(1-34), the TRCa maximum was greater after ERT than at baseline (99.4% +/- 0.1% vs. 99.0% +/- 0.1%; P < 0.0001), resulting in decreased calcium excretion (0.9 +/- 0.20 vs. 1.43 +/- 0.20 mumol/dL glomerular filtrate; P < 0.001). Thus, in early postmenopause, the major mechanism of increased renal calcium conservation after ERT is an increase in TRCa due to an increase in serum PTH because of estrogen-induced inhibition of bone resorption. However, ERT also may directly increase the TRCa maximum in response to PTH.

This article has been cited by other articles:

				S. H. Jeong, S. H. Choi, J. Y. Kim, J. W. Koo, H. J. Kim, and J. S. Kim Osteopenia and osteoporosis in idiopathic benign positional vertigo Neurology, March 24, 2009; 72(12): 1069 - 1076. [Abstract] [Full Text] [PDF]

				L. A Weiss, E. Barrett-Connor, and D. von Muhlen Ratio of n-6 to n-3 fatty acids and bone mineral density in older adults: the Rancho Bernardo Study Am. J. Clinical Nutrition, April 1, 2005; 81(4): 934 - 938. [Abstract] [Full Text] [PDF]

				I. M. Dick, A. Devine, J. Beilby, and R. L. Prince Effects of endogenous estrogen on renal calcium and phosphate handling in elderly women Am J Physiol Endocrinol Metab, February 1, 2005; 288(2): E430 - E435. [Abstract] [Full Text] [PDF]

				S. A. Jelinsky, H. A. Harris, E. L. Brown, K. Flanagan, X. Zhang, C. Tunkey, K. Lai, M. V. Lane, D. K. Simcoe, and M. J. Evans Global Transcription Profiling of Estrogen Activity: Estrogen Receptor {alpha} Regulates Gene Expression in the Kidney Endocrinology, February 1, 2003; 144(2): 701 - 710. [Abstract] [Full Text] [PDF]

				B. L. Riggs, S. Khosla, and L. J. Melton III Sex Steroids and the Construction and Conservation of the Adult Skeleton Endocr. Rev., June 1, 2002; 23(3): 279 - 302. [Abstract] [Full Text] [PDF]

				H. K. Kamel Low-Dose Thiazide and Bone Density Ann Intern Med, February 5, 2002; 136(3): 252 - 252. [Full Text] [PDF]

				D. T. Villareal, E. F. Binder, D. B. Williams, K. B. Schechtman, K. E. Yarasheski, and W. M. Kohrt Bone Mineral Density Response to Estrogen Replacement in Frail Elderly Women: A Randomized Controlled Trial JAMA, August 15, 2001; 286(7): 815 - 820. [Abstract] [Full Text] [PDF]

				B. J. Orr-Walker, A. M. Horne, M. C. Evans, A. B. Grey, M. A. F. Murray, A. R. McNeil, and I. R. Reid Hormone Replacement Therapy Causes a Respiratory Alkalosis in Normal Postmenopausal Women J. Clin. Endocrinol. Metab., June 1, 1999; 84(6): 1997 - 2001. [Abstract] [Full Text]

				A. J. FELSENFELD and M. RODRIGUEZ Phosphorus, Regulation of Plasma Calcium, and Secondary Hyperparathyroidism: A Hypothesis to Integrate a Historical and ModernPerspective J. Am. Soc. Nephrol., April 1, 1999; 10(4): 878 - 890. [Full Text]

				S. Khosla, L. J. Melton III, E. J. Atkinson, W. M. O’Fallon, G. G. Klee, and B. L. Riggs Relationship of Serum Sex Steroid Levels and Bone Turnover Markers with Bone Mineral Density in Men and Women: A Key Role for Bioavailable Estrogen J. Clin. Endocrinol. Metab., July 1, 1998; 83(7): 2266 - 2274. [Abstract] [Full Text]

				H. M. Heshmati, S. Khosla, M. F. Burritt, W. M. O’Fallon, and B. L. Riggs A Defect in Renal Calcium Conservation May Contribute to the Pathogenesis of Postmenopausal Osteoporosis J. Clin. Endocrinol. Metab., June 1, 1998; 83(6): 1916 - 1920. [Abstract] [Full Text]

				S. Khosla, E. J. Atkinson, L. J. Melton III, and B. L. Riggs Effects of Age and Estrogen Status on Serum Parathyroid Hormone Levels and Biochemical Markers of Bone Turnover in Women: A Population-Based Study J. Clin. Endocrinol. Metab., May 1, 1997; 82(5): 1522 - 1527. [Abstract] [Full Text] [PDF]