Scanning electron microscopy of 2,8-dihydroxyadenine crystals and stones

The lack of purine salvage enzyme, adenine phosphoribosyltransferase (APRT), leads to 2,8-dihydroxyadenine stone formation and/or crystalluria because it is insoluble in urine. Urolithiasis composed of 2,8-dihydroxyadenine is not only formed in a complete defect of APRT, but also in a partial deficiency of this enzyme. The defect is inherited as an autosomal recessive trait, the homozygous state is associated with high urinary levels of 2,8-dihydroxyadenine and with crystalluria, calculus formation, and potential nephrotoxicity. Determination of the APRT activity will facilitate quantification of the enzyme deficiency and elucidation of the hereditary history. 2,8-dihydroxyadenine excretion in the 24-hour urine and its circadian rhythm were determined using a new method of high performance liquid chromatography determination. By means of a standard case presentation, we illustrate the analysis of urinary sediments and calculi as well as the scanning electron microscopic images of this kind of stone.