Abstract: TH-PO554
Evidence for Disordered Acid-Base Balance in Calcium Stone Formers
Session Information
- Bone and Mineral Metabolism: Basic
November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Bone and Mineral Metabolism
- 401 Bone and Mineral Metabolism: Basic
Authors
- Bergsland, Kristin J., University of Chicago, Chicago, Illinois, United States
- Worcester, Elaine M., University of Chicago, Chicago, Illinois, United States
- Coe, Fredric L., University of Chicago, Chicago, Illinois, United States
Background
Normal women (W) have higher urine pH (UpH) than normal men (M). Thus W are predisposed to urine calcium phosphate (CaP) crystallization which occurs at higher UpH, and CaP stones are more common in W; M are more likely to form calcium oxalate (CaOx) stones due to lower UpH. In a General Clinical Research Center, we investigated whether W CaOx stone formers (SF) and M CaP SF, who are atypical for their sex, have abnormal acid-base balance or renal acidification and if so, what components of acid-base metabolism are responsible for the altered UpH.
Methods
We measured UpH and determinants of acid-base regulation in 25 normal subjects (13 M), 18 CaOx SF (12 M) and 17 CaP SF (9 M). We collected 15 urines and 20 blood samples over a 15 hour day; diet was fixed. Gastrointestinal anion excretion (GIAE) = [(Na + K + Ca+ Mg) - (Cl + P)] in urine.
Results
Ammonia (NH4) excretion was higher in CaP SF of both sexes and W CaOx SF vs same sex normal (N) even after adjustment for sulfate and GIAE (Table). Urine citrate (U Cit) and fractional excretion of citrate (FE Cit) were lower than N in M CaP SF. Net acid excretion (NAE) was high in all M SF vs normal M. W CaOx SF had lower GIAE than W CaP SF or W N (1.50 ± 0.26 mEq/hr vs 2.48 ± 0.22 or 3.11 ± 0.18 resp., p<0.05).
Conclusion
CaP SF of both sexes and women CaOx SF have different but clear disorders of acid-base handling, the former seemingly localized to abnormal renal proximal tubule acidification and the latter to aspects of food anion absorption.
| Women | Men | |||||
| N | CaP | CaOx | N | CaP | CaOx | |
| U TCO2 | 0.73±0.06 | 0.86±0.60 | 0.80±0.08 | 0.96±0.85# | 0.97±0.06 | 0.84±0.05 |
| U TA | 0.52±0.02 | 0.53±0.02 | 0.56±0.03 | 0.56±0.02$ | 0.64±0.03#+ | 0.56±0.02 |
| U NH4 | 1.09±0.04+$ | 1.41±0.05+ | 1.24±0.07 | 1.05±0.04$ | 1.41±0.05*+ | 1.16±0.04 |
| U NAE | 0.88±0.07 | 1.04±0.08 | 1.05±0.1 | 0.65±0.06#+$ | 1.07±0.08+ | 0.85±0.07 |
| U Phos | 0.98±0.04 | 1.04±0.04 | 0.97±0.05 | 1.08±0.04$ | 1.31±0.04#+ | 1.06±0.03 |
| U Cit | 0.18±0.01 | 0.17±0.01 | 0.16±0.01 | 0.14±0.01#$+ | 0.11±0.11#+ | 0.18±0.01 |
| FE Cit | 11.6±0.5 | 10.3±0.6 | 11.6±0.6 | 10.1±0.4#$ | 6.8±0.5#+ | 10.3±0.4 |
| UpH | 6.31±0.04 | 6.40±0.04+ | 6.19±0.05 | 6.26±0.03 | 6.32±0.04 | 6.35±0.04# |
Mean±SE. Fed period, adjusted for sulfate and GIAE. TCO2, total CO2; TA, titratable acidity. All urine excretions are mmol/hour/1.73m2. Symbols: #, differs from W, same stone type; +, differs from CaOx, same sex; $, differs from CaP, same sex; all comparisons p<0.05.
Funding
- NIDDK Support