Vol. 181, No. 4, Supplement, Wednesday, April 29, 2009 THE JOURNAL OF UROLOGY® 661

and control group, TT genotype showed significantly increased risk for urolithiasis than TG and GG genotypes (Table 1).

CONCLUSIONS: We concluded that HSPG2 gene polymorphism in regards of TT genotype might be one of the genetic factors affecting the CaOx stone formation. Although the etiopathogenesis remains unclear, this could help us for early determination of stone formers especially in endemic regions before the disease emerges.

Table 1. Genotypic frequencies of HSPG2 gene polymorphism

Genotypes Urolithiasis Group (n= 143) Control (n= 158)

GG 85 (59.44%) 85 (53.80%)

TG 54 (37.76%) 73 (46.20%)

TT 4 (2.80%) 0

p1 (GG/TT) = 0.04800, p2 (GG+GT/TT) = 0.03431

Source of Funding: None

1832CITRATE, MALATE, AND AKALI CONCENTRATIONS IN COMMONLY CONSUMED DIET SODAS: IMPLICATIONS FOR URINARY STONE PATIENTS

Brian H Eisner*, San Francisco, CA; John R Asplin, Chicago, IL; Marshall L Stoller, San Francisco, CA

INTRODUCTION AND OBJECTIVES: Citrate is a known inhibitor of calcium stone formation. The purpose of this study was to determine the citrate and total alkali concentrations (i.e. citrate + malate) in commonly consumed diet sodas to help direct dietary recommendations for patients with nephrolithaisis.

METHODS: Citrate, and malate were measured by ion chromatography using a Dionex ICS 2000 system (Dionex Corporation, Sunnyvale, CA) equipped with an AG-11 guard column and AS-11 analytical column in series. The mobile phase was potassium hydroxide at a flow rate of 2 ml/minute. Ion peaks were detected using a conductivity meter with the eluent background conductivity suppressed using an anion self-regenerating suppressor (ASRS Ultra II, Dionex Corp). Each beverage was diluted in 0.3 M boric acid and loaded onto the column using a 25 ul sample loop.

RESULTS: The results are shown in the table below. Diet 7-up contains the greatest amount of citrate delivered as alkali (9.79 meq/l) and Diet Sunkist Orange contains the greatest amount of total alkali (8.38 meq/l of citrate + 2.11 meq/l malate = 10.49 meq/l total alkali).

CONCLUSIONS: Several commonly consumed diet sodas contain moderate amounts of citrate and malate. This is helpful for dietary recommendations for patients with calcium nephrolithiasis and specifically those with hypocitraturia. Beverage malate content is important, as it will increase the total alkali delivered, which in turn augments citraturia.

Citrate, malate, and alkali content of commonly consumed diet sodas

Soda pH Citrate (mM)

Citrate as alkali (meq/l)

Malate (mM)

Malate as alkali (meq/l)

Total alkali (meq/l)

**Diet Sunkist Orange 3.56 10.4 8.38 3.6 2.11 10.49

*Diet 7-Up 3.52 12.5 9.79 0 0 9.79

Diet Canada Dry 3.6 8.3 6.88 3.4 2.1 8.98

Sierra Mist Free 3.41 11.3 8.11 0 0 8.11

Sprite Zero 3.39 11.3 7.97 0 0 7.97

Diet Orange Crush 3.41 6.7 4.84 5.6 2.78 7.62

Fresca 3.19 12.3 7.15 0 0 7.15

Diet Mountain Dew 3.31 10.3 6.78 0 0 6.78

Fanta Orange Zero 3.02 12.9 6.12 0 0 6.12

Diet Squirt 3.1 7.5 3.93 0 0 3.93

Diet Mug Root Beer 4.18 1.51 1.72 0 0 1.72

Caffeine Free Diet Coke 3.25 0.87 0.54 0 0 0.54

Diet Coke with Lime 3.13 0.87 0.47 0 0 0.47

Coke Zero 3.02 0.3 0.14 0 0 0.14

Caffeine Free Diet Pepsi 3.07 0.23 0 0 0 0

* greatest amount of citrate as alkali; ** greatest amount of total alkali

Source of Funding: None

1833URETERAL ANTI-RETROPULSIVE DEVICES DECREASE RENAL PELVIC PRESSURE

Tatum V Tarin, Stanford, CA; Rajesh Shinghal*, San Jose, CA

INTRODUCTION AND OBJECTIVES: Ureteral anti-retropulsive devices such as the Stone Cone®, N-Trap®, and Accordion® prevent proximal migration of stones during ureteroscopic lithotripsy. Irrigation during ureteroscopy can generate significant intrapelvic pressure within the kidney, which may lead to increased fluid absorption and pyelovenous backflow. The objective of this study was to determine the effect of ureteral anti-retropulsive devices on renal pressures in an ex-vivo porcine ureteroscopy model.

METHODS: Kidneys, ureter, and bladder were excised en bloc from a female pig. A 5 French urodynamic catheter (Cook Urological) was inserted into the renal pelvis and pressure transduced on a urodynamics system (Laborie Aquarius). Using a flexible ureteroscope (ACMI DUR-8) with normal saline irrigation at either 150 mm Hg or 300 mm Hg, baseline pressure was obtained at three distances from the ureteral orifice (10, 20, or 30 cm). Then, an anti-retropulsive device was inserted in parallel and deployed just proximal to the tip of the ureteroscope. Four pressure measurements were obtained. Data was analyzed with the Student’s t-test.

RESULTS: At an irrigation pressure of 300 mm Hg in the mid-ureteral location (20 cm from UO), all devices decreased the renal pelvic pressure (P<0.05). Statistically significant decreases in renal pelvic pressures were observed at all three locations in the ureter with the Accordion device (Figure 1). Comparison between the devices show the 10 mm Accordion to be the most effective in decreasing pressure. At 150 mm Hg, decreases in pressure were less pronounced and only statistically significant with the 10 mm Accordion.

CONCLUSIONS: Ureteral anti-retropulsive devices decrease renal pelvic pressures during ureteroscopy. The most pronounced decrease is seen with the 10 mm Accordion device. These devices, in addition to improving the efficiency of ureteroscopic lithotripsy, may reduce pylevenous backflow and potentially decrease the risk of systemic infection.