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Re: Omega-3 Fatty Acids Eicosapentaenoic Acid and Docosahexaenoic Acid in the Management of Hypercalciuric Stone Formers
UROLITHIASIS/ENDOUROLOGY
157
␥-carboxylation is regulated by this vitamin K dependent protein. The authors demonstrated that the expression of vitamin K epoxide reductase was less in the kidneys of patients with calcium oxalate nephrolithiasis compared to those with nonstone related obstructive nephropathy or renal cancer. They will need to demonstrate this result in the garden variety calcium oxalate stone former (one whose kidney is not being discarded into the pathology bucket) for this story to become more compelling. Dean Assimos, M.D.
Re: Prevalence and Metabolic Abnormalities of Vitamin D-Inadequate Patients Presenting With Urolithiasis to a Tertiary Stone Clinic M. A. Elkoushy, R. Sabbagh, B. Unikowsky and S. Andonian Division of Urology, McGill University Health Centre, McGill University, Montreal, Quebec, Canada Urology 2011; Epub ahead of print.
Objective: To assess the prevalence and metabolic abnormalities of patients with inadequate vitamin D (VD) presenting with urolithiasis to a tertiary stone clinic in North America. Material and Methods: A retrospective review of consecutive patients presenting from August 2009 to January 2010 was performed. Demographic and clinical data were collected together with metabolic stone workup, including 2 24-hour urine collections and serum 25-hydroxy VD [25(OH)D]. VD inadequacy (VDI) included VD deficiency and VD insufficiency defined as 25-(OH) VD levels ⬍20 ng/mL and 21–29 ng/mL, respectively. Results: Of 101 patients, 81 (80.2%) were found to have VDI: 34 (33.7%) were deficient and 47 (46.5%) had insufficient VD. Mean age was 50.4 ⫾ 15.8 years and the mean body mass index was 28.7 ⫾ 5.8 kg/m(2). Forty-two percent were smokers, 51% were recurrent stone formers, and 54% had positive family history of urolithiasis. Hyperparathyroidism was detected in 25.9% of patients, of which 91% of them were secondary to VDI. Hypocalcemia and hyperuricemia were found in 36% and 11% of patients, respectively. Of 81 VDI patients, 69 (85.2%) had complete 24-hour urine collections, of which 92.7% had at least one abnormality. However, only 40% of patients with normal VD had metabolic abnormalities (P ⬍.0001). The most prevalent pattern of urinary abnormalities in VDI patients were suboptimal volume (45%), hypocitraturia (24%), hypocalciuria (33%), hypercalciuria (20%), hyperuricosuria (16%), cystinuria (5%), and hyperoxaluria (7.2%). Conclusions: In this preliminary study, patients presenting with urolithiasis were found to have a high prevalence of inadequate VD associated with abnormalities on metabolic stone work-up. Editorial Comment: There is an epidemic of vitamin D deficiency and insufficiency in North America. The authors demonstrate the high prevalence of this condition in patients attending a tertiary stone clinic. The looming questions are what role, if any, do these conditions have in stone formation, and what is the impact of vitamin D replenishment on stone risk? Dean Assimos, M.D.
Re: Omega-3 Fatty Acids Eicosapentaenoic Acid and Docosahexaenoic Acid in the Management of Hypercalciuric Stone Formers O. Ortiz-Alvarado, R. Miyaoka, C. Kriedberg, D. A. Leavitt, A. Moeding, M. Stessman and M. Monga Department of Regional Urology, Cleveland Clinic, Cleveland, Ohio Urology 2012; 79: 282–286.
Objective: To investigate the use of fish oil in the dietary management of hypercalciuric stone formers. Prostaglandins have been linked to urinary calcium excretion, suggesting a role for omega-3 fatty
158
UROLITHIASIS/ENDOUROLOGY
acids in the treatment of hypercalciuric urolithiasis. Methods: We retrospectively studied a cohort of patients treated at our stone clinics from July 2007 to February 2009. Patients’ urinary risk factors for stone disease were evaluated with pre- and post-intervention 24-hour urine collections. All patients received empiric dietary recommendations for intake of fluids, sodium, protein, and citric juices. All subjects with hypercalciuria (urinary calcium ⬎250 mg/d for males or ⬎200 mg/d for females) on at least two 24-hour urine collections were counseled to supplement their diet with fish oil (1200 mg/d). Results: Twenty-nine patients were followed for 9.86 ⫾ 8.96 months. The mean age was 43.38 ⫾ 13.78 years. Urinary calcium levels decreased in 52% of patients, with 24% converting to normocalciuria. The average urinary calcium (mg/d) decreased significantly from baseline (329.27 ⫾ 96.23 to 247.47 ⫾ 84.53, P ⬍.0001). Urinary oxalate excretion decreased in 34% of patients. The average urinary oxalate (mg/d) decreased significantly from baseline (45.40 ⫾ 9.90 to 32.9 ⫾ 8.21, P ⫽ .0004). Urinary citrate (mg/d) increased in 62% of subjects from baseline (731.67 ⫾ 279.09 to 940.22 ⫾ 437.54, P ⫽ .0005). Calcium oxalate supersaturation decreased in 38% of the subjects significantly from baseline (9.73 ⫾ 4.48 to 3.68 ⫾ 1.76, P ⫽ .001). Conclusion: Omega-3 fatty acids combined with empiric dietary counseling results in a measurable decrease in urinary calcium and oxalate excretion and an increase in urinary citrate in hypercalciuric stone formers. Editorial Comment: While I agree with the authors that fish oil may have a role in the management of hypercalciuria and/or hyperoxaluria, the retrospective nature and lack of dietary control in this study do not provide support for this recommendation. Dean Assimos, M.D.
Re: Evaluation of the Optimal Frequency of and Pretreatment with Shock Waves in Patients With Renal Stones J. Y. Lee and Y. T. Moon Department of Urology, Chung-Ang University College of Medicine, Seoul, Korea Korean J Urol 2011; 52: 776 –781.
Purpose: Many studies have been carried out to increase the success rate of shock wave lithotripsy (SWL) and to reduce renal injury. We investigated the success rate after one session as well as urine N-acetyl--d-glucosaminidase (NAG) levels for the evaluation of renal injury according to shock wave frequency and pretreatment with low-energy shock waves during SWL. Materials and Methods: The study targeted 48 patients with renal stones who had undergone SWL. Patients were sequentially allocated into four groups according to shock wave frequency (60 or 120 shocks/min) and whether pretreatment had occurred. We documented total SWL operating number, success rate after first SWL, urine NAG, compliance, and the total cost for each patient. Results: There were 32 males and 16 females with an average age of 51.6 years. The average stone size was 7.06 mm, and there was no significant difference in stone size between the groups. The data showed that patients treated with a frequency of 60 shocks/min had a lower mean number of SWL sessions, 1.36 sessions for 60 shocks/min and 2.0 sessions for 120 shocks/min, respectively, which was statistically significant (p⬍0.05). When comparing NAG/creatinine ratios before and after SWL between those with and without pretreatment, there was no significant difference according to pretreatment (p⫽0.406). Conclusions: SWL treatment at a frequency of 60 shocks/ min yielded better outcomes, such as a lower number of SWL sessions, and had an increased success rate compared with SWL at 120 shocks/min. On the other hand, pretreatment did not impact renal injury. Therefore, SWL treatment at a frequency of 60 shocks/min could improve treatment efficacy more than that for SWL at 120 shocks/min. Editorial Comment: Improved fragmentation with the slower rate is expected and has been demonstrated in previous studies. It would have been interesting if the markers of
157
␥-carboxylation is regulated by this vitamin K dependent protein. The authors demonstrated that the expression of vitamin K epoxide reductase was less in the kidneys of patients with calcium oxalate nephrolithiasis compared to those with nonstone related obstructive nephropathy or renal cancer. They will need to demonstrate this result in the garden variety calcium oxalate stone former (one whose kidney is not being discarded into the pathology bucket) for this story to become more compelling. Dean Assimos, M.D.
Re: Prevalence and Metabolic Abnormalities of Vitamin D-Inadequate Patients Presenting With Urolithiasis to a Tertiary Stone Clinic M. A. Elkoushy, R. Sabbagh, B. Unikowsky and S. Andonian Division of Urology, McGill University Health Centre, McGill University, Montreal, Quebec, Canada Urology 2011; Epub ahead of print.
Objective: To assess the prevalence and metabolic abnormalities of patients with inadequate vitamin D (VD) presenting with urolithiasis to a tertiary stone clinic in North America. Material and Methods: A retrospective review of consecutive patients presenting from August 2009 to January 2010 was performed. Demographic and clinical data were collected together with metabolic stone workup, including 2 24-hour urine collections and serum 25-hydroxy VD [25(OH)D]. VD inadequacy (VDI) included VD deficiency and VD insufficiency defined as 25-(OH) VD levels ⬍20 ng/mL and 21–29 ng/mL, respectively. Results: Of 101 patients, 81 (80.2%) were found to have VDI: 34 (33.7%) were deficient and 47 (46.5%) had insufficient VD. Mean age was 50.4 ⫾ 15.8 years and the mean body mass index was 28.7 ⫾ 5.8 kg/m(2). Forty-two percent were smokers, 51% were recurrent stone formers, and 54% had positive family history of urolithiasis. Hyperparathyroidism was detected in 25.9% of patients, of which 91% of them were secondary to VDI. Hypocalcemia and hyperuricemia were found in 36% and 11% of patients, respectively. Of 81 VDI patients, 69 (85.2%) had complete 24-hour urine collections, of which 92.7% had at least one abnormality. However, only 40% of patients with normal VD had metabolic abnormalities (P ⬍.0001). The most prevalent pattern of urinary abnormalities in VDI patients were suboptimal volume (45%), hypocitraturia (24%), hypocalciuria (33%), hypercalciuria (20%), hyperuricosuria (16%), cystinuria (5%), and hyperoxaluria (7.2%). Conclusions: In this preliminary study, patients presenting with urolithiasis were found to have a high prevalence of inadequate VD associated with abnormalities on metabolic stone work-up. Editorial Comment: There is an epidemic of vitamin D deficiency and insufficiency in North America. The authors demonstrate the high prevalence of this condition in patients attending a tertiary stone clinic. The looming questions are what role, if any, do these conditions have in stone formation, and what is the impact of vitamin D replenishment on stone risk? Dean Assimos, M.D.
Re: Omega-3 Fatty Acids Eicosapentaenoic Acid and Docosahexaenoic Acid in the Management of Hypercalciuric Stone Formers O. Ortiz-Alvarado, R. Miyaoka, C. Kriedberg, D. A. Leavitt, A. Moeding, M. Stessman and M. Monga Department of Regional Urology, Cleveland Clinic, Cleveland, Ohio Urology 2012; 79: 282–286.
Objective: To investigate the use of fish oil in the dietary management of hypercalciuric stone formers. Prostaglandins have been linked to urinary calcium excretion, suggesting a role for omega-3 fatty
158
UROLITHIASIS/ENDOUROLOGY
acids in the treatment of hypercalciuric urolithiasis. Methods: We retrospectively studied a cohort of patients treated at our stone clinics from July 2007 to February 2009. Patients’ urinary risk factors for stone disease were evaluated with pre- and post-intervention 24-hour urine collections. All patients received empiric dietary recommendations for intake of fluids, sodium, protein, and citric juices. All subjects with hypercalciuria (urinary calcium ⬎250 mg/d for males or ⬎200 mg/d for females) on at least two 24-hour urine collections were counseled to supplement their diet with fish oil (1200 mg/d). Results: Twenty-nine patients were followed for 9.86 ⫾ 8.96 months. The mean age was 43.38 ⫾ 13.78 years. Urinary calcium levels decreased in 52% of patients, with 24% converting to normocalciuria. The average urinary calcium (mg/d) decreased significantly from baseline (329.27 ⫾ 96.23 to 247.47 ⫾ 84.53, P ⬍.0001). Urinary oxalate excretion decreased in 34% of patients. The average urinary oxalate (mg/d) decreased significantly from baseline (45.40 ⫾ 9.90 to 32.9 ⫾ 8.21, P ⫽ .0004). Urinary citrate (mg/d) increased in 62% of subjects from baseline (731.67 ⫾ 279.09 to 940.22 ⫾ 437.54, P ⫽ .0005). Calcium oxalate supersaturation decreased in 38% of the subjects significantly from baseline (9.73 ⫾ 4.48 to 3.68 ⫾ 1.76, P ⫽ .001). Conclusion: Omega-3 fatty acids combined with empiric dietary counseling results in a measurable decrease in urinary calcium and oxalate excretion and an increase in urinary citrate in hypercalciuric stone formers. Editorial Comment: While I agree with the authors that fish oil may have a role in the management of hypercalciuria and/or hyperoxaluria, the retrospective nature and lack of dietary control in this study do not provide support for this recommendation. Dean Assimos, M.D.
Re: Evaluation of the Optimal Frequency of and Pretreatment with Shock Waves in Patients With Renal Stones J. Y. Lee and Y. T. Moon Department of Urology, Chung-Ang University College of Medicine, Seoul, Korea Korean J Urol 2011; 52: 776 –781.
Purpose: Many studies have been carried out to increase the success rate of shock wave lithotripsy (SWL) and to reduce renal injury. We investigated the success rate after one session as well as urine N-acetyl--d-glucosaminidase (NAG) levels for the evaluation of renal injury according to shock wave frequency and pretreatment with low-energy shock waves during SWL. Materials and Methods: The study targeted 48 patients with renal stones who had undergone SWL. Patients were sequentially allocated into four groups according to shock wave frequency (60 or 120 shocks/min) and whether pretreatment had occurred. We documented total SWL operating number, success rate after first SWL, urine NAG, compliance, and the total cost for each patient. Results: There were 32 males and 16 females with an average age of 51.6 years. The average stone size was 7.06 mm, and there was no significant difference in stone size between the groups. The data showed that patients treated with a frequency of 60 shocks/min had a lower mean number of SWL sessions, 1.36 sessions for 60 shocks/min and 2.0 sessions for 120 shocks/min, respectively, which was statistically significant (p⬍0.05). When comparing NAG/creatinine ratios before and after SWL between those with and without pretreatment, there was no significant difference according to pretreatment (p⫽0.406). Conclusions: SWL treatment at a frequency of 60 shocks/ min yielded better outcomes, such as a lower number of SWL sessions, and had an increased success rate compared with SWL at 120 shocks/min. On the other hand, pretreatment did not impact renal injury. Therefore, SWL treatment at a frequency of 60 shocks/min could improve treatment efficacy more than that for SWL at 120 shocks/min. Editorial Comment: Improved fragmentation with the slower rate is expected and has been demonstrated in previous studies. It would have been interesting if the markers of