Experimental and computer modelling speciation studies of the effect of pH and phosphate on the precipitation of calcium and magnesium salts in urine

Darn, Simon M; Sodi, Ravinder; Ranganath, L.; Roberts, Norman B.; Duffield, John R.

doi:10.1515/cclm.2006.034

Cited by 14 publications

(14 citation statements)

References 14 publications

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“…Whether the urine was treated with acid to improve calcium solubility was considered a potential effect modifier for this regression analysis. Studies were categorized as acidic if 1) the urine was treated with acid before analysis or 2) if the mean urine pH was 6.5 (17) in both treatment arms. Researchers were contacted to clarify whether the urine samples were treated with acid before analysis if this detail was not clear in the report (16,22,34).…”

Section: Methods Of the Meta-analysismentioning

confidence: 99%

“…Calcium forms insoluble salts in urine with pH 6.5 (17). The insoluble calcium is not measured when urine calcium is analyzed by laboratories (17,18), which may create a measurement error for the association between the NAE and calcium excretion.…”

Section: Introductionmentioning

confidence: 99%

“…The insoluble calcium is not measured when urine calcium is analyzed by laboratories (17,18), which may create a measurement error for the association between the NAE and calcium excretion. It is possible that some or the entire amount of calcium seen with more acidic urine is due to better measurement of calcium in the acidic urine, and the presumed cause and effect relation could be due to confounding by measurement error.…”

Section: Introductionmentioning

confidence: 99%

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Meta-analysis of the quantity of calcium excretion associated with the net acid excretion of the modern diet under the acid-ash diet hypothesis

Fenton

Eliasziw

Lyon

et al. 2008

The American Journal of Clinical Nutrition

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Meta-analysis of the quantity of calcium excretion associated with the net acid excretion of the modern diet under the acid-ash diet hypothesis [1][2][3][4] Tanis R Fenton, Michael Eliasziw, Andrew W Lyon, Suzanne C Tough, and David A Hanley ABSTRACT Background: The acid-ash diet hypothesis of osteoporosis suggests that acid from the modern diet causes a demineralization of the skeleton, and mobilized bone calcium is excreted. A systematic approach has not been used to summarize the findings of the numerous studies about the hypothesis. Objectives: The purpose of this meta-analysis was to estimate the quantity of net acid excretion and calciuria associated with the modern diet, to assess the association between acid excretion and calcium excretion, and to assess the influence of urine preservatives on calcium measurement. Design: We systematically searched for trials of the acid-ash hypothesis and conducted a meta-analysis. Results: Twenty-five of 105 studies met the inclusion criteria. The estimated quantity of net acid excretion from the weighted average of the control diets from 11 studies was 47 mEq/d. The increase in urinary calcium with a change in renal net acid excretion depended on whether the urine was acidic or alkaline (P 0.001). A significant linear relation was observed between net acid excretion and calcium excretion for both acidic and alkaline urine (P 0.001). The estimated change in urine calcium associated with a change of 47 mEq of net acid excretion in acidic urine was 1.6 mmol/d (66 mg/d) of calcium. Conclusion: Evidence suggests a linear association between changes in calcium excretion in response to experimental changes in net acid excretion. However, this finding is not evidence that the source of the excreted calcium is bone or that this calciuria contributes to the development of osteoporosis.

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Section: Methods Of the Meta-analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Meta-analysis of the quantity of calcium excretion associated with the net acid excretion of the modern diet under the acid-ash diet hypothesis

Fenton

Eliasziw

Lyon

et al. 2008

The American Journal of Clinical Nutrition

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“…Interestingly, additional gene ablation of Atp6v1b1 in Trpv5 knockout mice resulted in normalization of urinary pH levels and led to the tubular precipitation of Ca 2ϩ -phosphate in the medullary CD ( Figure 1) (32). From previous studies it was known that the formation of alkaline urine increases the risk for Ca 2ϩ -phosphate precipitation (33). Therefore, renal stones commonly occur in distal renal tubular acidosis patients, who display a urinary acidification defect and concomitant hypercalciuria (36).…”

Section: Casr Activation Decreases the Risk To Renal Stone Formation mentioning

confidence: 98%

“…The crystallization of Ca 2ϩ -phosphate occurs via the conversion of phosphate to its divalent form (HPO 4 2Ϫ ) in an alkaline, rather than in an acidic, environment. From this can be hypothesized that a decrease in urinary pH can prevent Ca 2ϩ -phosphate crystal formation (33). Acid/base transport processes take place along different nephron segments to control tubular fluid pH levels (34).…”

Section: Casr Activation Decreases the Risk To Renal Stone Formation mentioning

confidence: 99%

Role of the Calcium-Sensing Receptor in Reducing the Risk for Calcium Stones

Renkema

Bindels²,

Hoenderop³

2011

Clinical Journal of the American Society of Nephrology

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SummaryThe tight control of blood Ca 2؉ levels within a narrow range is essential for the performance of vital physiologic functions. Muscle contraction, neuronal excitation, and intracellular signaling processes acquisitively require Ca 2؉ . It is the concerted action of intestine, bone, and kidney that controls the Ca 2؉ balance through the regulation of intestinal absorption, bone (de)mineralization, and renal excretion of Ca 2؉ , respectively. Along the nephron, fine-tuning of blood Ca 2؉ levels takes place by Ca 2؉ reabsorption. The calciotropic hormones regulate Ca 2؉ transport processes, leading to whole-body Ca 2؉ homeostasis and, importantly, preserving a constant Ca 2؉ concentration in the blood. Defects in renal Ca 2؉ handling can lead to hypercalciuria, consecutive kidney stone formation, and obstructive nephropathy. Here we give an overview of the key players involved in normal Ca 2؉ management and describe the in-depth investigations on a renal hypercalciuric model of disease, the Trpv5 knockout mouse, which naturally displays molecular adaptations that prevent Ca 2؉ precipitation in the kidney.

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JESS at thirty: Strengths, weaknesses and future needs in the modelling of chemical speciation

May

2015

Applied Geochemistry

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The current status of the software package JESS (Joint Expert Speciation System), which has been developed over the last 30 years, is described. Chemical speciation models of seawater and of metalion complexation in human blood plasma are used as large equilibrium systems to explore the present capabilities of the code and database. Strengths of JESS are considered to be (a) the power and flexibility of its command-driven programs, (b) the size, generality and openness of its reaction database, (c) its automatic facility to achieve thermodynamic consistency, and (d) its ability to partition chemical reactions to model kinetic constraints. A special feature of JESS is its ability automatically to generate a complete, stand-alone FORTRAN program for any particular chemical equilibrium model that has been developed. Weaknesses of JESS include the lack of a graphical user interface, the resulting effort required in familiarisation, and certain limitations regarding pressure and temperature corrections in concentrated solutions. However, the most troublesome issuescommon to all 'ion-association' frameworks -are due to inadequacies in the thermodynamic data available from the literature and to persistent deficiencies in the fundamental theory of concentrated electrolyte solutions. Accordingly, work on JESS has commenced to construct a global parameterisation facility using both reaction data and the physicochemical properties of strong electrolytes in aqueous solution (including solubilities) intended to improve model function testing and to provide even better mechanisms for data harmonisation.

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Experimental and computer modelling speciation studies of the effect of pH and phosphate on the precipitation of calcium and magnesium salts in urine

Cited by 14 publications

References 14 publications

Meta-analysis of the quantity of calcium excretion associated with the net acid excretion of the modern diet under the acid-ash diet hypothesis

Meta-analysis of the quantity of calcium excretion associated with the net acid excretion of the modern diet under the acid-ash diet hypothesis

Role of the Calcium-Sensing Receptor in Reducing the Risk for Calcium Stones

JESS at thirty: Strengths, weaknesses and future needs in the modelling of chemical speciation

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