Hyperoxaluria is related to whewellite and hypercalciuria to weddellite: What happens when crystalline conversion occurs?

Abstract

International audienceWhile calcium oxalate monohydrate (whewellite: CaC₂ O ₄ H ₂ O) kidney stones are related to hyperoxaluria, calcium oxalate dihydrate (weddellite: CaC ₂ O ₄(2 + x)H ₂ O) ones are mainly associated with hypercalciuria. Crystalline conversion from weddellite to whe-wellite introduces a contradiction between Fourier transform infrared (FTIR) spectra which indicate the presence of whewellite and the fact that bipyramid crystallites, a morphology specific of weddellite, can be observed. It constitutes thus a major problem for clinicians as hyperoxaluria and hypercalciuria are associated with very different aetiologies and treatments. In this contribution, the complete set of data including neutron diffraction experiments, observations through a last generation field emission scanning electron microscope as well as 3D and 2D cross-section visualisations derived from the mComputed Tomography measurements seems to explain some particular features observed on FTIR spectra related to the crystalline conversion from weddellite to whewellite. The structural hypothesis which is proposed is related to the formation of amorphous whewellite, a new polymorph recently synthesised. Thus, in such cases, special attention should be paid to the stone morphology (and not FTIR spectrum), which is a major element for clinical diagnosis as already underlined for other types of urinary calculi

Improvement of Urinary Stones Analysis Combining Morphological Analysis and Infrared Spectroscopy

“…According to the morphoconstitutional classification of Daudon et al [1], COM is generally associated with hyperoxaluric states, while COD suggests the existence of hypercalciuria. However, since the conversion from COD to the more stable COM crystalline phase is a well-known phenomenon [9], some derangement from this strict dichotomy is expected. In the eight stones which were discordant (the case of #13, #18, #29, #42, #60, #67, #87, and #90 (Table 5)), the disagreement was only observed on the surface of the stone that was most recently formed.…”

Characterization of Calcium Oxalate Hydrates and the Transformation Process

“…FTIR shows characteristic bands of COM, whereas SEM reveals the presence of bipyramidal crystals, characteristics of COD. [11] Since both species are related to different pathologies (for example, COM to hyperoxaluria and COD to hypercalciuria), distinguish the origin of the crystal grown is important to associate the kidney stones with the corresponding etiology and treatment. [11] On the other hand, COD is not always transformed.…”

“…[11] Since both species are related to different pathologies (for example, COM to hyperoxaluria and COD to hypercalciuria), distinguish the origin of the crystal grown is important to associate the kidney stones with the corresponding etiology and treatment. [11] On the other hand, COD is not always transformed. Hence, it is present as weddellite in renal calculi and, in the same way, weddellite is often detected in oxalate films occurring on the surface of several ancient monuments.…”

Calcium oxalate kidney stones, where is the organic matter?: A synchrotron based infrared microspectroscopy study

“…9,11 The differentiation between COM (being formed as monohydrated) and TRA (coming from the transformation of COD), in any of the transformation stages, is of great importance since their origins are caused by different pathologies, for example, COD nephroliths are related to hypercalciuria, while COM ones are related to hyperoxaluria. 9,12,13 Therefore, the study of this transformation process, as well as the stabilization of the dihydrated species, is very important to understand the physiopathology, to propose adequate treatment and, to prevent the patients' recurrence. 9,14,15 The matrix of kidney stones, including the oxalocalcic ones, is not only formed by crystalline phases; there are also macromolecules (organic matter), such as, proteins, lipids, carbohydrates, and glycosaminoglycans, 16 as well as trace elements, such as, Zn an Sr ions, 17 incorporated into the crystals structures.…”

“…9,12,13 Therefore, the study of this transformation process, as well as the stabilization of the dihydrated species, is very important to understand the physiopathology, to propose adequate treatment and, to prevent the patients' recurrence. 9,14,15 The matrix of kidney stones, including the oxalocalcic ones, is not only formed by crystalline phases; there are also macromolecules (organic matter), such as, proteins, lipids, carbohydrates, and glycosaminoglycans, 16 as well as trace elements, such as, Zn an Sr ions, 17 incorporated into the crystals structures. The role of those molecules is not fully understood, since they can act as promotors or inhibitors of the renal calculi development by participating on any of the formation steps (nucleation, aggregation and/or growth).…”