Urolithiasis pp 337-342 | Cite as

Dietary Structure and Urinary Composition in a Stone-Free Population

  • M. Modlin
  • P. J. Davies
  • D. Crawford


The large number of pure calcium oxalate stones identified by various investigators, coupled with observations that more frequently calcium oxalate forms the major component of stones containing both calcium oxalate and calcium phosphate have been among the reasons for the suggestion that crystals of calcium oxalate nucleate stone formation. Fifty two renal stones were analyzed by infrared spectroscopy. Infrared spectroscopy is particularly sensitive for the detection of phosphate and will detect a calcium phosphate concentration of 1% in a calcium oxalate stone. Forty calcium-stones were identified. All 40 contained meaningful amounts of calcium phosphate. None contained only calcium oxalate. Very small spontaneously passed renal stones represent the nucleus of the stone surrounded by a minimum of crystal deposition. Scanning electron microscopy coupled with chemical microanalysis of the fracture surface of very small spontaneously passed calcium-stones revealed the invariable presence of both calcium phosphate and calcium oxalate. The calcium phosphate occurred either as multiple clusters of conglomerates of crystals (Figure 1), or as a single cluster of conglomerates of crystals, lying among conglomerates of calcium oxalate crystals. The total area occupied by calcium phosphate is smaller than that occupied by calcium oxalate. The probable non-existence of pure calcium oxalate stones, the ubiquity of calcium phosphate, its invariable presence in minuscle calciumstones, all three of which have been demonstrated by these studies, are consistent with published data which suggest that crystals of calcium phosphate nucleate stone formation and support the proposition.


Calcium Phosphate Phytic Acid Renal Stone Calcium Oxalate Calcium Oxalate Crystal 
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Copyright information

© Springer Science+Business Media New York 1981

Authors and Affiliations

  • M. Modlin
    • 1
    • 2
  • P. J. Davies
    • 1
    • 2
  • D. Crawford
    • 1
    • 2
  1. 1.Department of Urology and Department of Medical BiochemistryMedical School, University of Cape TownSouth Africa
  2. 2.Electron Microscope UnitUniversity of Cape TownSouth Africa

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