Edwin L. Prien

Cystine Calculi—Rough and Smooth: A New Clinical Distinction

Four stones each from 2 populations of cystine calculi, 1 with a rough external surface (cystine-R) and the other smooth (cystine-S), were studied for their crystal structure with stereoscopic and scanning electron microscopy. Two stones each of cystine-R and cystine-S, calcium oxalate monohydrate, calcium oxalate dihydrate, struvite plus apatite and brushite were fragmented with extracorporeal shock wave lithotripsy and the fragmentability was compared. Fragments resulting from cystine-R and cystine-S extracorporeal shock wave lithotripsy were examined under the stereoscope to assess the plane of cleavage or fracture. Results show that cystine-R stones are comprised of well formed blocks of hexagonal crystals, whereas cystine-S calculi have small, irregular and poorly formed interlacing crystals. The center of cystine-R stones was similar to that of the periphery but the center of cystine-S stones was formed of blocks of hexagons similar to but smaller than the cystine-R calculi. Fragmentation with extracorporeal shock wave lithotripsy revealed that cystine-S stones are the least fragile, calcium oxalate dihydrate and struvite plus apatite were the most fragile, and cystine-R, brushite and calcium oxalate monohydrate calculi were in the intermediate fragility range. The possibility of the patient having a cystine-R calculus should be considered during therapeutic procedures.

Percutaneous catheter dissolution of cystine calculi.

In 11 kidneys with presumed cystine stones that were symptomatic and obstructing, percutaneous nephrostomy and stone lavage with either acetylcysteine-bicarbonate solution or tromethamine-E were performed. There were 7 complete stone dissolutions: 2 of 6 attempts with acetylcysteine-bicarbonate alone, 3 of 5 with tromethamine-E, 1 partial with acetylcysteine-bicarbonate, which was completed with tromethamine-E, and 1 proved mixed stone (cystine and calcium phosphate) that required acetylcysteine-bicarbonate and hemiacidrin. In 1 case tromethamine-E irrigation was 97 per cent complete but a few tiny caliceal fragments remained. There were 3 failures of chemolysis: 2 pure cystine stones (1 each acetylcysteine-bicarbonate and tromethamine-E) and 1 mixed calculus with a surface shell of calcium oxalate. Irrigation time was 6 to 42 days for the 7 unoperated kidneys. Tromethamine-E appears to be a more effective agent for cystine stone dissolution. Percutaneous nephrostomy and dissolution are an alternative to an operation in patients with cystine calculous disease.

Changes in stone composition over two decades: evaluation of over 10,000 stone analyses

AbstractnTo examine the changes in stone composition from 1990 to 2010. A retrospective review was performed of all renal and ureteral stones submitted from the state of Massachusetts to a single laboratory (Laboratory for Stone Research, Newton, MA) for the years 1990 and 2010. Stone composition was determined by infrared spectroscopy and/or polarizing microscopy. A total of 11,099 stones were evaluated (56.7xa0% from 1990, 43.3xa0% from 2010). From 1990 to 2010, the percentage of stones from females (i.e., female/male ratio) increased significantly (29.8xa0% in 1990 to 39.1xa0% in 2010, pxa0<xa00.001). Among women, from 1990 to 2010, there was a significant increase in stones which were >50xa0% uric acid (7.6–10.2xa0%, pxa0<xa00.005) and a significant decrease in struvite stones (7.8–3.0xa0%, pxa0<xa00.001). Among women with calcium stones, the xa0% apatite per stone decreased significantly (20.0 vs. 11.7xa0%, pxa0<xa00.001). Among men, there were no changes in stones which were majority uric acid (11.7–10.8xa0%, pxa0=xa00.2). Among men with calcium stones, the xa0% apatite per stone increased significantly (9.8 vs. 12.5xa0%, pxa0<xa00.001). Males also demonstrated a significant increase in both cystine (0.1–0.6xa0%, pxa0<xa00.001) and struvite stones (2.8–3.7xa0%, pxa0=xa00.02). The epidemiology of stone disease continues to evolve and appears to vary according to gender. While some of these findings may be related to population changes in body mass index and obesity, the etiology of others remains unclear.

Dissolution of calcified gallstones. Part I. Correlation of in vitro dissolution kinetics in methyl tert-butyl ether with patterns of calcification by computed tomography.

RATIONALE AND OBJECTIVES.The authors evaluated the relationship between stone computed tomography (CT) attenuation patterns and the kinetics of dissolution with methyl tertbutyl ether (MTBE). METHODS.Single moderately and heavily calcified gallstones from 40 patients were selected from a gallstone library and classified for pattern of calcification by in vitro CT scan (dense, rim, core, and laminated). Each stone was placed in a 10-mL aliquot of MTBE for 24 hours. Stone residue was blotted dry and weighed at 8, 16, and 24 hours. Results were normalized with respect to stone size. RESULTS.Only 1 of 40 (4%) specimens dissolved to particulate matter that was smaller than 2 mm. All (6 of 6) stones that were densely calcified showed virtually no dissolution. The rate of gallstone dissolution varied temporally within the rim, core, and laminated stone categories and was related to the composition of the layer exposed to the solvent at any given time. CONCLUSION.The success and rate of dissolution may be predicted by the pattern of calcification as determined by computed tomography (CT).

Cystine Calculi: Two Types

Four stones each from two populations of cystine calculi, one with rough external surface (cystine-R) and the other with smooth external surface (cystine-S), were studied for their crystalline structure with scanning electron microscopy and stereoscopy. Two stones each of cystine-R and cystine-S, calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD), struvite/apatite, and brushite were fragmented with shock wave lithotripsy and the fragmentability compared. Fragments resulting from cystine-R and cystine-S shock wave lithotripsy were examined under a stereoscope to assess plane of cleavage or fracture. Results showed that cystine-R is comprised of well-formed blocks of hexagonal crystals; whereas, cystine-S has small, irregular crystals that are poorly formed and interlacing. The center of a cystine-R stone was similar to that of the periphery, but the center of a cystine-S stone was formed of blocks of hexagons similar to but smaller than the cystine-R. Fragmentation with shock wave lithotripsy revealed that cystine-S is the least fragile, COD and struvite/apatite are most fragile, and cystine-R, brushite, and COM are in the intermediate fragility range. The possibility of the patient having cystine-R calculus should be considered during therapeutic procedures.

Dissolution of calcified gallstones. Part II. Evaluation of edetic acid preparations for dissolution of residue after in vitro methyl tert-butyl ether treatment.

RATIONALE AND OBJECTIVES.The authors assessed the potential of edetic acid (EDTA) preparations to dissolve the residue of calcified gallstones partially treated with methyl tert-butyl ether (MTBE). METHODS.Nineteen triplets (57 gallstones) were submitted to dissolution in EDTA, urea-EDTA, and an MTBE control for 48 hours after initial partial dissolution in MTBE for 24 hours. Results were compared with findings at specimen computed tomography and crystallographic analysis. All data were corrected for differences in stone size. RESULTS.In all three treatment groups (EDTA, urea-EDTA, MTBE), almost identical dissolution outcomes were observed within each triplet. Most triplets that dissolved displayed a laminated or a core-calcification pattern and consisted primarily of cholesterol. Specimens that dissolved poorly in all three groups displayed dense calcifications or thick calcified rims and were classified as pigment stones. CONCLUSION.Because no statistically significant differences in dissolution were found among the EDTA, urea-EDTA, and MTBE treatments, we conclude that EDTA preparations are not superior to the continued use of MTBE for dissolution of residue after initial MTBE treatment.

Metabolic Aspects of Urinary Stone Disease

The field of urinary stone disease can conveniently be divided into those diseases that clearly result from excessive supersaturation of the urine for the offending crystalline species and those that do not. Recent developments in the former area are mainly confined to describing new disorders or improving therapy; there is little debate on pathogenesis and hardly a reference to physical chemistry. For calcium stone disease, the situation is quite different. Not only is excessive supersaturation for calcium oxalate often difficult to demonstrate, but normals may have crystalluria. The lofty realms of complex physical chemistry are increasingly invoked. Further, in contrast to other stone diseases, the contribution of diet to both the cause and treatment of calcium stone disease must be considered. It is this disease entity that presents the greatest continuing challenge.