Calcium Oxalate Crystalluria: Crystal Size in Urine

Abstract

Studies of calcium oxalate crystals in urine suggest similarities to crystal growth in calcium oxalate renal calculi. Previous reports indicate that urinary crystals in patients in whom stones form are larger than those in normal subjects. We report herein a study on crystal size by structure and habit (shape) based on direct microscopic measurement of crystals in urine of 27 normal subjects and in 6 of 22 patients in whom stones form. The mean size of all crystals in normal subjects is 12.0 plus or minus 7.8 micrometers. Calcium oxalate monohydrate crystals are significantly smaller than calcium oxalate dihydrate (p less than 0.01). In 22 patients with stones there was no correlation between crystalluria and severity or duration of disease. The mean crystal size in 6 patients did not support the conclusion that patients in whom stones form excrete larger crystals than normal subjects.

Evaluation of the Risk of Stone Formation: Study on Crystalluria in Patients with Recurrent Calcium Oxalate Urolithiasis

“…In practice, collected urine is most often maintained at room temperature or incubated at 37 °C while waiting to be examined 30-120 min after their emission. An additional delay at low temperature can, however, be beneficial by amplifying the process of crystallization, thus facilitating the characterization of the crystalline phases [18,22,23,26], Our observations are consistent with most previous publications which noted frequent calcium oxalate crystalluria not only in stone formers (9-40% of cases), but also in normal controls (2-11 %). According to these studies, crystalluria in stone formers is statistically comparable to that of healthy con trols or, in contrast, differs significantly, being character ized, in particular, by higher incidence, more voluminous crystals or more numerous aggregates [18-20, 22, 23, 26].…”

Crystalluria

“…The container with the whole volume of urine should be released to the laboratory within 2 h from voiding, kept at room temperature and processed without delay [12].…”

Modulation of Calcium Oxalate Dihydrate Growth by Selective Crystal-face Binding of Phosphorylated Osteopontin and Polyaspartate Peptide Showing Occlusion by Sectoral (Compositional) Zoning

“…It has been reported that the occurrence of COM, the more thermodynamically stable polymorph of calcium oxalate, is often at the core of most kidney stones and is approximately twice as frequent as COD (2), although both crystal types typically exist to some degree in most stones (3,4). COM is commonly found in the urine of "stone formers," but seldom is seen in healthy urine; on the other hand, COD crystals are typically found in the urine of both healthy people and stone formers and are routinely excreted during urination (5)(6)(7). Importantly, in patients with severe uremia and hypercalciuria, elongated, large rod-shaped COD crystals are not only often observed but are the sole mineral phase present in the kidneys in these pathologies (8,9).…”