Renal Stones of Calcium Phosphate: Physicochemical Basis for Their Formation

Pak, Charles Y.C.; Diller, Esther; Smith, G. W.; Howe, Effie

doi:10.3181/00379727-130-33648

Cited by 29 publications

(24 citation statements)

References 1 publication

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“…2 and 3). Many patients with idiopathic hypercalciuria and nephrolithiasis excrete urine specimens whose activity product ratios exceed the range of formation product ratios reported here (1). Further, normocalciuri6 patients with stones may excrete urine with a similar degree of supersaturation during infections of the urinary tract with ureasplitting organisms.…”

Section: The Formation Product Ratiomentioning

confidence: 97%

“…All patients received a diet containing 400-600 mg/day of calcium for 5 or more days before, and during, the study. One 24-hr urine specimen was obtained from each patient; it was kept cold without preservative (1,2). The urinary calcium concentration among the patients with hypercalciuria was over 200 mg/day, with a mean value of 269 mg/day; in the remaining subjects and controls it aver- Values are given as mean ±SD.…”

Section: Materials and Methods Clinical Datamentioning

confidence: 99%

“…The activity product of [Ca2+] X [HP042-] of this specimen decreased markedly, and the solid phase that precipitated proved on x-ray diffraction to be hydroxyapatite rather than brushite. DISCUSSION We have previously proposed a new scheme for the pathogenesis of renal stones containing calcium phosphate, wherein brushite plays a regulatory role (1,2). When calcium salt forms from urine on an artificial matrix of collagen, the initial mineral phase formed (or the crystal nidus) is brushite (4).…”

Section: The Formation Product Ratiomentioning

confidence: 99%

“…When this precipitate forms on an organic matrix or is added to a preexisting stone, it is composed of brushite (CaHPO4 * 2H20), and is deposited when the activity product of [Ca2+] X [HP042-] in the urine exceeds the activity product (K.,) of brushite (1)(2)(3)(4).…”

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confidence: 99%

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Spontaneous Precipitation of Brushite in Urine: Evidence that Brushite Is the Nidus of Renal Stones Originating as Calcium Phosphate

Pak

Eanes

Ruskin

1971

Proc. Natl. Acad. Sci. U.S.A.

102

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Further evidence that brushite plays a regulatory role in renal stone formation was provided by the identification of brushite as the first precipitate that appears in supersaturated urine by spontaneous precipitation. Calcium chloride was added to induce supersaturation in urine specimens from twelve subjects with and twelve subjects without nephrolithiasis.The first precipitate in all specimens with pH below 6.9 was identified as brushite by x-ray diffraction and shown to have a calcium-phosphorus ratio of approximately 1.0.The activity product of [Ca'+i X [HP0421-necessary to produce a precipitate ranged from 2.2 to 3.5 times the solubility product of brushite, but the range and mean were the same for both groups of subjects.The activity product of [Cal+] X [HPO42-] in the supernatant (after spontaneous precipitation) was not significantly different from that obtained after incubation of the same urine specimen with synthetic brushite.These results provide conclusive evidence that brushite constitutes the solid phase formed by spontaneous precipitation from acidic urine supersaturated with respect to calcium and phosphorus; they suggest that the nidus for calcium-containing renal stones is brushite as well.Physicochemical factors controlling the formation of calciumcontaining renal stones cannot be understood until the initial precipitate is identified. When this precipitate forms on an organic matrix or is added to a preexisting stone, it is composed of brushite (CaHPO4 * 2H20), and is deposited when the activity product of [Ca2+] X [HP042-] in the urine exceeds the activity product (K.,) of brushite (1-4).In earlier studies, a ratio of the solubility product of the actual urinary K.,, for brushite to that of urine with an added excess of solid brushite allowed quantitative calculation of the tendency for stone growth and corrected for any error in the calculation of activities for Ca2+ and HP042-(2).These results were used to explain growth of stones in some patients with hypercalciuria and some with urine persistently alkaline as a result of therapy with alkali or of urinary-tract infection by urea splitters. In the first group, the urine is supersaturated with respect to brushite, primarily because of an abnormally high concentration of Ca2+ ions. Stone formation is prevented when the concentration of urinary calcium (and thus the activity product for brushite) is lowered by the feeding of nonabsorbable chelators of calcium, or, in patients with hyperparathyroidism, by its surgical correction. In the second group, the urine is supersaturated primarily because of an abnormally high concentration of HP042-ions; stone formation is prevented when the urinary concentration of HP042-(and the activity product for brushite) is lowered by avoidance of alkali or by elimination of infection.The conclusion that brushite is indeed the initial nidus that forms from urine onto an organic matrix was supported by the demonstration that the activity product for brushite controls nidation on an artificial "matrix" ...

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Section: The Formation Product Ratiomentioning

confidence: 97%

Section: Materials and Methods Clinical Datamentioning

confidence: 99%

Section: The Formation Product Ratiomentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Spontaneous Precipitation of Brushite in Urine: Evidence that Brushite Is the Nidus of Renal Stones Originating as Calcium Phosphate

Pak

Eanes

Ruskin

1971

Proc. Natl. Acad. Sci. U.S.A.

102

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“…In previous communications (5,6), urine specimens from patients with idiopathic hypercalciuria and recurrent renal calculi were shown to be usually supersaturated with respect to brushite (CaHPO4 . 2H20).…”

Section: Introductionmentioning

confidence: 99%

Calcification of collagen by urine in vitro: dependence on the degree of saturation of urine with respect to brushite

Pak¹,

Ruskin²

1970

J. Clin. Invest.

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A B S T R A C T A state of supersaturation of urine with respect to brushite is considered to be important in the formation of renal stones composed of calcium phosphate. 56 supersaturated urine specimens and 44 undersaturated specimens were incubated with collagen (Sigma collagen). Most of the supersaturated specimens calcified the collagen, whereas none of the undersaturated ones did so. Among samples which calcified the collagen, the activity product of Ca"+ and HPO4 after incubation with collagen was essentially the same as that after incubation of the same specimen with brushite; it usually differed from that obtained after incubation with octacalcium phosphate or hydroxyapatite. The molar calcium-tophosphorus ratio of the solid phase in collagen was approximately 1. These results suggested that the solid phase formed in collagen is brushite. This conclusion was confirmed by the direct identification of brushite in collagen by X-ray diffraction.

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Sodium Cellulose Phosphate: Mechanism of Action and Effect on Mineral Metabolism

Pak¹

1973

The Journal of Clinical Pharmacology and New Drugs

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Renal Stones of Calcium Phosphate: Physicochemical Basis for Their Formation

Cited by 29 publications

References 1 publication

Spontaneous Precipitation of Brushite in Urine: Evidence that Brushite Is the Nidus of Renal Stones Originating as Calcium Phosphate

Spontaneous Precipitation of Brushite in Urine: Evidence that Brushite Is the Nidus of Renal Stones Originating as Calcium Phosphate

Calcification of collagen by urine in vitro: dependence on the degree of saturation of urine with respect to brushite

Sodium Cellulose Phosphate: Mechanism of Action and Effect on Mineral Metabolism

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