Surafel Gebreselassie

Dyslipidemia and Kidney Stone Risk

PURPOSE We studied the impact of dyslipidemia on 24-hour urinalysis and stone composition. MATERIALS AND METHODS We retrospectively identified patients with nephrolithiasis who underwent 24-hour urinalysis and lipid profile evaluation within 3 months. Patients were divided into groups based on total cholesterol, high density lipoprotein, nonhigh density lipoprotein and triglycerides. The groups were compared based on demographic data, diabetes, hypertension and each component of 24-hour urinalysis and stone composition. Multivariate analysis and linear regression were performed to control for potential confounders, including age, gender, body mass index, diabetes and hypertension. RESULTS A total of 2,442 patients with a mean age of 51.1 years were included in study. On multivariate analysis patients with high total cholesterol had significantly higher urinary potassium and calcium, those with low high density lipoprotein or high triglycerides had significantly higher urinary sodium, oxalate and uric acid with lower pH, and those with high nonhigh density lipoprotein had higher urinary sodium and uric acid. Regarding stone composition, high total cholesterol and triglycerides were significantly associated with a higher uric acid stone rate (p = 0.006 and <0.001, respectively). Linear regression showed a significant association of nonhigh density lipoprotein with higher urinary sodium (p = 0.011) and uric acid (p <0.001) as well as triglycerides and higher uric acid (p = 0.017), and lower urinary pH (p = 0.005). CONCLUSIONS There is a link between dyslipidemia and kidney stone risk that is independent of other components of metabolic syndrome such as diabetes and obesity. Specific alterations in the patient lipid profiles may portend unique aberrations in urine physicochemistry and stone risk.

Gout, Stone Composition and Urinary Stone Risk: A Matched Case Comparative Study

PURPOSE We established the most common stone composition, and serum and urinary biochemical features in patients with gout and urolithiasis. MATERIALS AND METHODS We retrospectively searched for the records of patients diagnosed with gout among all those in our stone registry. A matched case cohort of stone formers was generated from our registry who had the same age, gender and body mass index. Primary end points were baseline 24-hour urinary metabolic panels and stone composition. Medications were considered. Groups were compared using the Student t and chi-square/Fisher exact tests with significance considered at p <0.05. RESULTS For stone panel evaluation 181 patients met our inclusion criteria. There was no significant difference in 24-hour uric acid between the nongout and gout cohorts but hyperoxaluria was more common in patients with gout (74% vs 61%, p = 0.009). For stone composition analysis 393 patients were included. The gout cohort had lower calcium oxalate monohydrate (39.4% vs 54.7%), calcium oxalate dihydrate (6.0% vs 11.2%) and calcium phosphate (9.6% vs 14.1%) but higher uric acid (42.7% vs 18.2%, each p <0.001). Pure uric acid stones were more common in patients with gout (52.2% vs 22.3%, p <0.001), while calcium oxalate monohydrate (45.2% vs 68.6%, p <0.001), calcium oxalate dihydrate (0.6% vs 3.5%, p = 0.017) and calcium phosphate (1.6% vs 4.9%, p = 0.033) were more common in nongout cases. Patients with gout who were on allopurinol had fewer pure uric acid stones (30.4% vs 56.4%) and more calcium oxalate monohydrate stones (69.6% vs 40.7%, each p <0.001) than those without medication. CONCLUSIONS Uric acid stones are the most common pure stone composition in patients with gout but 48% have nonuric acid stones. Allopurinol changes the stone composition distribution in patients with gout to a pattern similar to that in stone formers without gout.

Type-2 Diabetes and Kidney Stones: Impact of Diabetes Medications and Glycemic Control

OBJECTIVE To evaluate the impact of diabetic medications and glycemic control on the urine pH, 24-hour urine stone risk profile, and stone composition. PATIENTS AND METHODS We retrospectively reviewed our database searching for type-2 diabetic patients with kidney stones from July 2002 to January 2013. Patients were divided in 2 groups according to their diabetic medications: insulin vs oral antihyperglycemics. Patients were compared based on their urine collections and stone composition. A linear regression was done to assess which variables could predict a low urine pH. In a subgroup analysis, patients on thiazolidinediones (ie, pioglitazone) were compared with patients on other oral antihyperglycemics. RESULTS We analyzed 1831 type-2 diabetic patients with stone disease; 375 (20.5%) were included in the insulin group and 1456 (79.5%) in the antihyperglycemics group. Linear regression revealed male gender (P = .011) and insulin therapy (P <.001) as protective factors of low urine pH, whereas HbA1c level (P <.001) was inversely related to the urine pH (odds ratio, -0.066; 95% confidence interval, -0.096 to -0.036; P <.001). There were no significant differences in other 24-h urine stone risk parameters or stone composition between the groups. There were also no significant differences in the subgroup analysis. CONCLUSION Urine pH is inversely related to HbA1c level. Insulin therapy is associated with higher urine pH than oral antihyperglycemic agents despite higher HbA1c suggesting that insulin may modify urine pH independent of glycemic control.

Absolute Hounsfield Unit Measurement on Noncontrast Computed Tomography Cannot Accurately Predict Struvite Stone Composition

BACKGROUND The purpose of our study was to determine, in vivo, whether single-energy noncontrast computed tomography (NCCT) can accurately predict the presence/percentage of struvite stone composition. METHODS We retrospectively searched for all patients with struvite components on stone composition analysis between January 2008 and March 2012. Inclusion criteria were NCCT prior to stone analysis and stone size ≥4 mm. A single urologist, blinded to stone composition, reviewed all NCCT to acquire stone location, dimensions, and Hounsfield unit (HU). HU density (HUD) was calculated by dividing mean HU by the stones largest transverse diameter. Stone analysis was performed via Fourier transform infrared spectrometry. Independent sample Students t-test and analysis of variance (ANOVA) were used to compare HU/HUD among groups. Spearmans correlation test was used to determine the correlation between HU and stone size and also HU/HUD to % of each component within the stone. Significance was considered if p<0.05. RESULTS Fourty-four patients met the inclusion criteria. Struvite was the most prevalent component with mean percentage of 50.1%±17.7%. Mean HU and HUD were 820.2±357.9 and 67.5±54.9, respectively. Struvite component analysis revealed a nonsignificant positive correlation with HU (R=0.017; p=0.912) and negative with HUD (R=-0.20; p=0.898). Overall, 3 (6.8%) had <20% of struvite component; 11 (25%), 25 (56.8%), and 5 (11.4%) had 21% to 40%, 41% to 60%, and 61% to 80% of struvite, respectively. ANOVA revealed no difference among groups regarding HU (p=0.68) and HUD (p=0.37), with important overlaps. When comparing pure struvite stones (n=5) with other miscellaneous stones (n=39), no difference was found for HU (p=0.09) but HUD was significantly lower for pure stones (27.9±23.6 v 72.5±55.9, respectively; p=0.006). Again, significant overlaps were seen. CONCLUSIONS Pure struvite stones have significantly lower HUD than mixed struvite stones, but overlap exists. A low HUD may increase the suspicion for a pure struvite calculus.

Genitourinary manifestations of sickle cell disease.

Sickle cell disease is a common genetic disorder characterized by sickling of red blood cells under conditions of reduced oxygen tension. In turn, sickling leads to intravascular hemolysis and vaso-occlusive events with subsequent tissue ischemia-reperfusion injury affecting multiple organs, including the genitourinary system. Our review of the genitourinary manifestations of sickle cell disease focuses on sickle cell nephropathy, priapism, and other genitourinary complications such as papillary necrosis and renal medullary carcinoma. Sickling can lead to nephropathy, priapism, papillary necrosis, and renal medullary carcinoma.

Restoration of Renal Allograft Function via Reduced-Contrast Percutaneous Revascularization of Transplant Renal Artery Stenosis

Transplant renal artery stenosis (TRAS), the most common vascular complication of kidney transplantation, can lead to heart failure, uncontrolled hypertension, and irreversible dysfunction of the transplanted kidney. Percutaneous revascularization can improve outcomes in well-selected patients with symptomatic TRAS, but the intervention itself poses risk to the transplanted kidney because of the quantities of nephrotoxic contrast solution that often are used. We report the case of a patient with TRAS who, 5 months after undergoing a kidney transplant, developed allograft dysfunction and heart failure that required hemodialysis. We performed angioplasty and stenting of the TRAS, using intravascular ultrasonography and fluoroscopy as our primary imaging methods. To minimize further damage to a potentially viable kidney, the volume of intravascular contrast medium used was trivial (a total of 9 cc). Revascularization of the patients TRAS restored his renal function: within 4 weeks of the procedure, he no longer needed hemodialysis, and his heart failure symptoms had resolved. This case emphasizes the value of early definitive treatment of TRAS and the usefulness of intravascular ultrasonography to minimize the amount of contrast medium used in endovascular procedures.

Evaluation of Kidney Function and Structure in Potential Living Kidney Donors: Implications for the Donor and Recipient

Kidney transplantation is the best treatment for patients with end-stage renal disease and recipients of living kidney donors fare better than recipients of deceased donors. In view of the shortage of organ supply and the long waiting list, expansion of the living donor pool has been sought. Importantly, donor acceptance criteria must first and foremost be grounded in concerns for donor safety. Recent studies suggesting that live kidney donors may have higher rates of end-stage renal disease in the long term compared with otherwise similar healthy persons highlights the critical importance of pre-donation evaluation of renal function and structure, and careful application in donor selection criteria. The quality of organs from living donors may also affect recipient outcomes. Because donor kidney function, histology, and anatomy pertain to the quality of the donated organ, living donor characterization of the factors associated with these features is important to the donor as well as the recipient.

2095 GOUT, STONE COMPOSITION AND URINARY STONE RISK: A CASE MATCHED COMPARATIVE STUDY

Abstract PURPOSE: to establish the most common stone composition, serum and urinary biochemical features of patients with gout and urolithiasis. MATERIALS AND METHODS: we retrospectively searched for patients with gout diagnosis among those in our stone registry. A case-matched cohort of stone-formers was generated from our registry having the same age, gender and BMI. Primary end-points were baseline 24-hour urinary metabolic panels and stone composition. Medications were taken in consideration. Groups were compared using Students t test and Chi-square/Fishers exact test (significant if p<0.05). RESULTS: Stone panel evaluation: 181 patients met our inclusion criteria. There was no significant difference in 24-hour UA between non-gout and gout cohorts; hyperoxaluria was more common in gout patients (74 vs. 61%; p=0.009). Stone composition analysis: 393 patients were included. Gout cohort had lower amount of CaOMH (39.4 vs. 54.7%), CaODH (6.0 vs. 11.2%) and CaPh (9.6 vs. 14.1%; p<0.001) and higher of UA (42.7 vs. 18.2%; p<0.001). Pure UA stones were more common in gout patients (52.2 vs. 22.3%; p<0.001); CaOMH (45.2 vs. 68.6%; p<0.001), CaOHD (0.6 vs. 3.5%; p=0.017) and CaPh (1.6 vs. 4.9%; p=0.033) were more frequent in non-gout patients. Gout patients taking allopurinol had less pure UA (30.4 vs. 56.4%; p=0.001) and more CaOMH stones (69.6 vs. 40.7%; p<0.001) than those without medications. CONCLUSIONS: UA stones are the most common pure stone composition in patients with gout, but 48% will have non-UA stones. Allopurinol changes the distribution of stone composition in patients with gout, to a pattern similar to non-gout stone formers.