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Is calcium oxalate nucleation in postprandial urine of males with idiopathic recurrent calcium urolithiasis related to calcium phosphate nucleation and the intensity of stone formation? Studies allowing insight into a possible role of urinary free citrate and protein.

Abstract

In idiopathic recurrent urolithiasis (IRCU) calcium oxalate and calcium phosphate are components of stones. It is not sufficiently known whether in urine the nucleation (liquid-solid transition) of each salt requires a different environment, if so which environment, and whether there is an impact on stone formation. Nucleation was induced by in vitro addition of oxalate or calcium to post-test meal load whole urine of male stone patients (n=48), showing normal daily and baseline fasting oxaluria. The maximally tolerated (until visible precipitates occur) concentration of oxalate (T-Ox) or calcium (T-Ca) was determined; additionally evaluated were other variables in urine, including total, complexed and free citrate (F-Cit), protein (albumin, non-albumin protein) and the clinical intensity (synonymous metabolic activity; MA) of IRCU. In the first of three trials the accumulation of substances in stone-forming urine was verified (trial-V); in the second (clinical trial 1) two strata of T-Ox (Low, High) were compared; in the third (clinical trial 2) IRCU patients (n=27) and a control group (n=13) were included to clarify whether in stone-forming urine the first crystal formed was calcium oxalate or calcium phosphate, and to identify the state of F-Cit. T-Ox was studied at the original pH (average < 6.0), T-Ca at prefixed pH 6.0; the precipitates were subjected to electron microscopy and element analysis. Trial-V: Among the urinary substances accumulating at the indicated pHs were calcium, oxalate and phosphate, and the crystal-urine ratios were compatible with the nucleation of calcium oxalate, calcium-poor and calcium-rich calcium phosphate; citrate, protein and potassium also accumulated. Clinical trial 1: the two strata exhibited an inverse change of T-Ox and T-Ca, the ratio T-Ox/T-Ca and MA. The initial (before induction of Ox or Ca excess) supersaturation of calcium oxalate and brushite were unchanged, with the difference of proteinuria being borderline. Several correlations were significant (p < or = 0.05): urine pH with citrate and volume, protein with volume and MA, T-Ox with T-Ca and MA. Clinical trial 2: in patients with reduced urine volume and moderate urine calcium excess, the first precipitate appeared to be calcium oxalate, followed by amorphous calcium phosphate. Conversely, when the calcium excess was extreme, calcium-rich hydroxyapatite developed, followed by calcium oxalate; F-Cit, not total and complexed citrate, was decreased in IRCU vs. male controls; F-Cit rose pH-dependently, and the ratio F-Cit at original pH vs. F-Cit at pH 6.0 correlated inversely with the nucleation index T-Ox/T-Ca; MA correlated inversely with the ratio F-Cit at pH 6.0, respectively, original pH, but directly with the urinary albumin/non-albumin protein ratio. In summary 1) to study calcium oxalate and calcium phosphate nucleation in whole urine of IRCU patients is feasible; 2) at this crystallization stage the two substances, dominant in calcium stones, appear intimately linked, 3) in stone-forming urine, calcium phosphate may be ubiquitously present, likely as particles < 0.22 microm; 4) together with co-precipitation of calcium oxalate and calcium phosphate, low F-Cit and alteration of proteinuria may act in concert and accelerate stones.

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  • Authors+Show Affiliations

    ,

    Mineral Metabolism and Endocrine Research Laboratory, Department of Surgery, University of Erlangen, Erlangen, Germany.

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    Source

    MeSH

    Adult
    Aged
    Calcium
    Calcium Chloride
    Calcium Oxalate
    Calcium Phosphates
    Citric Acid
    Creatine
    Crystallization
    Crystallography
    Data Interpretation, Statistical
    Electron Probe Microanalysis
    Humans
    Hydrogen-Ion Concentration
    Male
    Middle Aged
    Oxalates
    Phosphates
    Postprandial Period
    Potassium
    Proteins
    Proteinuria
    Regression Analysis
    Urinary Calculi
    Urine

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    15080561

    Citation

    Schwille, Paul O., et al. "Is Calcium Oxalate Nucleation in Postprandial Urine of Males With Idiopathic Recurrent Calcium Urolithiasis Related to Calcium Phosphate Nucleation and the Intensity of Stone Formation? Studies Allowing Insight Into a Possible Role of Urinary Free Citrate and Protein." Clinical Chemistry and Laboratory Medicine, vol. 42, no. 3, 2004, pp. 283-93.
    Schwille PO, Schmiedl A, Manoharan M. Is calcium oxalate nucleation in postprandial urine of males with idiopathic recurrent calcium urolithiasis related to calcium phosphate nucleation and the intensity of stone formation? Studies allowing insight into a possible role of urinary free citrate and protein. Clin Chem Lab Med. 2004;42(3):283-93.
    Schwille, P. O., Schmiedl, A., & Manoharan, M. (2004). Is calcium oxalate nucleation in postprandial urine of males with idiopathic recurrent calcium urolithiasis related to calcium phosphate nucleation and the intensity of stone formation? Studies allowing insight into a possible role of urinary free citrate and protein. Clinical Chemistry and Laboratory Medicine, 42(3), pp. 283-93.
    Schwille PO, Schmiedl A, Manoharan M. Is Calcium Oxalate Nucleation in Postprandial Urine of Males With Idiopathic Recurrent Calcium Urolithiasis Related to Calcium Phosphate Nucleation and the Intensity of Stone Formation? Studies Allowing Insight Into a Possible Role of Urinary Free Citrate and Protein. Clin Chem Lab Med. 2004;42(3):283-93. PubMed PMID: 15080561.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Is calcium oxalate nucleation in postprandial urine of males with idiopathic recurrent calcium urolithiasis related to calcium phosphate nucleation and the intensity of stone formation? Studies allowing insight into a possible role of urinary free citrate and protein. AU - Schwille,Paul O, AU - Schmiedl,Angelika, AU - Manoharan,Mahimaidos, PY - 2004/4/15/pubmed PY - 2005/1/29/medline PY - 2004/4/15/entrez SP - 283 EP - 93 JF - Clinical chemistry and laboratory medicine JO - Clin. Chem. Lab. Med. VL - 42 IS - 3 N2 - In idiopathic recurrent urolithiasis (IRCU) calcium oxalate and calcium phosphate are components of stones. It is not sufficiently known whether in urine the nucleation (liquid-solid transition) of each salt requires a different environment, if so which environment, and whether there is an impact on stone formation. Nucleation was induced by in vitro addition of oxalate or calcium to post-test meal load whole urine of male stone patients (n=48), showing normal daily and baseline fasting oxaluria. The maximally tolerated (until visible precipitates occur) concentration of oxalate (T-Ox) or calcium (T-Ca) was determined; additionally evaluated were other variables in urine, including total, complexed and free citrate (F-Cit), protein (albumin, non-albumin protein) and the clinical intensity (synonymous metabolic activity; MA) of IRCU. In the first of three trials the accumulation of substances in stone-forming urine was verified (trial-V); in the second (clinical trial 1) two strata of T-Ox (Low, High) were compared; in the third (clinical trial 2) IRCU patients (n=27) and a control group (n=13) were included to clarify whether in stone-forming urine the first crystal formed was calcium oxalate or calcium phosphate, and to identify the state of F-Cit. T-Ox was studied at the original pH (average < 6.0), T-Ca at prefixed pH 6.0; the precipitates were subjected to electron microscopy and element analysis. Trial-V: Among the urinary substances accumulating at the indicated pHs were calcium, oxalate and phosphate, and the crystal-urine ratios were compatible with the nucleation of calcium oxalate, calcium-poor and calcium-rich calcium phosphate; citrate, protein and potassium also accumulated. Clinical trial 1: the two strata exhibited an inverse change of T-Ox and T-Ca, the ratio T-Ox/T-Ca and MA. The initial (before induction of Ox or Ca excess) supersaturation of calcium oxalate and brushite were unchanged, with the difference of proteinuria being borderline. Several correlations were significant (p < or = 0.05): urine pH with citrate and volume, protein with volume and MA, T-Ox with T-Ca and MA. Clinical trial 2: in patients with reduced urine volume and moderate urine calcium excess, the first precipitate appeared to be calcium oxalate, followed by amorphous calcium phosphate. Conversely, when the calcium excess was extreme, calcium-rich hydroxyapatite developed, followed by calcium oxalate; F-Cit, not total and complexed citrate, was decreased in IRCU vs. male controls; F-Cit rose pH-dependently, and the ratio F-Cit at original pH vs. F-Cit at pH 6.0 correlated inversely with the nucleation index T-Ox/T-Ca; MA correlated inversely with the ratio F-Cit at pH 6.0, respectively, original pH, but directly with the urinary albumin/non-albumin protein ratio. In summary 1) to study calcium oxalate and calcium phosphate nucleation in whole urine of IRCU patients is feasible; 2) at this crystallization stage the two substances, dominant in calcium stones, appear intimately linked, 3) in stone-forming urine, calcium phosphate may be ubiquitously present, likely as particles < 0.22 microm; 4) together with co-precipitation of calcium oxalate and calcium phosphate, low F-Cit and alteration of proteinuria may act in concert and accelerate stones. SN - 1434-6621 UR - https://www.unboundmedicine.com/medline/citation/15080561/Is_calcium_oxalate_nucleation_in_postprandial_urine_of_males_with_idiopathic_recurrent_calcium_urolithiasis_related_to_calcium_phosphate_nucleation_and_the_intensity_of_stone_formation_Studies_allowing_insight_into_a_possible_role_of_urinary_free_citrate_and_protein_ L2 - https://www.degruyter.com/doi/10.1515/CCLM.2004.052 DB - PRIME DP - Unbound Medicine ER -