Association of urinary citrate with acid-base status, bone resorption, and calcium excretion in older men and women.

Association of urinary citrate with acid-base status, bone resorption, and calcium excretion in older men and women.

J Clin Endocrinol Metab. 2017 Dec 01;:

Authors: Shea MK, Dawson-Hughes B

Abstract
Context: Elevated urine net acid excretion (NAE), indicative of subclinical metabolic acidosis, has been associated with higher bone turnover. While NAE is the gold-standard clinical measure of acid-base status, it is impractical to measure in most clinical/research settings. Urine citrate, which is commonly measured, changes in response to acid-base status, but its association with bone turnover is uncertain.
Objective: To evaluate the association between change in urine citrate and change in bone turnover and calcium excretion.
Design, Intervention, Participants: 233 healthy men and women ≥60 years were randomly assigned to 1.0 mmol/kg/day potassium bicarbonate (KHCO3), 1.5 mmol/kg/day KHCO3, or placebo for 84 days.
Outcome measures: Urine citrate, NAE, N-telopeptide of collagen type-I (NTX), calcium excretion and serum amino-terminal-propeptide of type-1-procollagen (P1NP) were measured pre- and post-intervention.
Results: Urine citrate increased dose-dependently following KHCO3 supplementation (p-trend<0.001). The urine citrate change was significantly inversely associated with P1NP change (p=0.021), but not with change in NTX (p=0.051) or calcium excretion (p=0.652). The change in NAE was positively associated with change in NTX and calcium excretion (p≤0.003), but not with change in P1NP (p=0.051). When the urine citrate change and NAE change were included in the same model, the urine citrate change was not associated with change in NTX, calcium excretion, or serum P1NP (all p≥0.086), whereas change in NAE remained associated with change in NTX and calcium excretion (p≤0.003).
Conclusion: Urine citrate may not be a suitable alternative to NAE when assessing acid-base status in relation to bone turnover in older adults.

PMID: 29211866 [PubMed - as supplied by publisher]

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