Urolithiasis is one of the most common urologic diseases in industrialized societies. More than 80% of renal stones are composed of calcium oxalate, and small changes in urinary oxalate concentrations affect the risk of stone formation. Elucidation of the source of oxalate and its mechanism of transport is crucial for understanding the etiology of urolithiasis. Sources of oxalate can be both endogenous and exogenous. With regard to oxalate transport, tests were carried out to prove the function of solute-linked carrier 4 (SLC4) and SLC26. The molecular mechanism of urolithiasis caused by SLC4 and SLC26 is still unclear. The growing number of studies on the molecular physiology of SLC4 and SLC26, together with knockout genetic mouse model experiments, suggest that SLC4 and SLC26 may be a contributing element to urolithiasis. This review summarizes recent research on the sources of oxalate and characterization of the oxalate transport ionic exchangers SLC4 and SLC26, with an emphasis on different physiological defects in knockout mouse models including kidney stone formation. Furthermore, SLC4 and SLC26 exchangers provide new insight into urolithiasis and may be a novel therapeutic target for modification of urinary oxalate excretion.

This study established a quantitative micro‐Raman spectroscopic (MRS) method for measuring multicomponents (binary and ternary compositions) of prevalent urine calculi extracted from the ureter after the ureteroscopic lithotripsy (URSL) procedure. The analysis used calibration curves of known mixtures of synthetically prepared calcium oxalate monohydrate (COM), hydroxyapatite (HAP), calcium oxalate dehydrate (COD), dicalcium phosphate dehydrate (DCPD), and uric acid. A variety of samples of binary and ternary mixtures including COM/HAP, COM/COD, COD/HAP, COM/uric acid, COD/uric acid, HAP/uric acid, HAP/DCPD, and COM/COD/HAP were prepared in various concentration ratios for use as the basis of the quantitative analysis. Intensities of the characteristic bands at 961 cm−1 (IHAP), 986 cm−1 (IDCPD), 1402 cm−1 (IUricAcid), 1462 cm−1 (ICOM), and 1477 cm−1 (ICOD) were used for the calculation. We derived a set of quantitative analysis equations for the ternary composition COD/COM/HAP group by combining two binary equations from the groups COM/COD and the HAP/COM. This study quantitatively measured 18 urine samples extracted from the 18 patients' ureters after the URSL procedure. Fifteen samples were binary mixtures, whereas three samples were ternary mixtures. This research successfully applied the quantitative MRS‐based analysis technique from bench to bedside. Copyright © 2012 John Wiley & Sons, Ltd.

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