Exp Clin Endocrinol Diabetes 2007; 115 - P02_126
DOI: 10.1055/s-2007-972533

Acid-base metabolism is independently correlated to bone turnover

CC Brueck 1, R Rienmüller 2, G Riedmueller 1, M Benedikt 1, K Kovaleva 2, J Gerdova 1, A Fahrleitner-Pammer 1, B Obermayer-Pietsch 1, H Dobnig 1
  • 1Medizinische Universität Graz, Klinische Abteilung für Endokrinologie und Nuklearmedizin, Graz, Austria
  • 2Medizinische Universität Graz, Klinische Abteilung für allgemeine radiologische Diagnostik, Graz, Austria

Human physiology has evolved to maintain blood pH values within a narrow range of 7.39 to 7.42. This is ensured by several buffering and accompanying adaptive mechanisms. Several organs are involved in this important regulation. The calcium carbonate/calcium phosphate system is part of the buffering system. In the present study we intended to show the influence of the acid-base system on bone turnover (BT).

Methods: Bone mineral density (BMD) at the upper thoracic spine was measured by electronic beam CT (EBCT) in 369 participants (m=251, f=118). Baseline EBCT scans following the same protocol have been performed on average 5.1 y (1.1–8.8 y) prior to the present measurement. Since trabecular bone mass shows a higher correlation to BT than the cortical bone envelope trabecular BMD of the vertebral bodies was measured. Mean age of the patients at the time of the present EBCT measurement was 62±11 y (range 22–88). At this time a venous blood-sampling including an additional arterial blood gas analysis was performed.

Results: Crosslaps as a marker of ongoing BT showed a negative significant correlation to base excess (BE r=-0.11, P=0.03), however, was not correlated to HCO3, pO2, pCO2 and serum ph. This correlation remained significant after adjustment for age and BMI (r=-0.11, P=0.02). There was no univariate correlation between BE (r=0.01, P=0.78) and HCO3 (r=0.04, P=0.44) and the present thoracic trabecular spine BMD. The mean change between the present and the baseline BMD, however, was correlated to the current BE as well as to the current serum HCO3 concentrations in the univariate (BE r=0.15, P=0.004; HCO3 r=0.13, P=0.01) and multivariate analysis (BE r=-0.13, P=0.01; HCO3 r=0.12, P=0.01) including age and BMI.

Conclusion: In summary, these results point towards an important role of acid-base metabolism in the short and long-term regulation of BT. As acidogenic situations seem to increase bone resorption and modulate bone loss a balanced acid-base metabolism should possibly be considered a new therapeutic goal in the management of bone diseases