Naim M Maalouf1, Mary Ann Cameron, Orson W Moe, Khashayar Sakhaee. 1. Charles and Jane Pak Center for Mineral Metabolism and Clinical Research and Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8885, USA. naim.maalouf@utsouthwestern.edu
Abstract
BACKGROUND AND OBJECTIVES: Type 2 diabetes is associated with excessively low urine pH, which increases the risk for uric acid nephrolithiasis. This study was conducted to assess the metabolic basis responsible for the excessive urinary acidity of individuals with type 2 diabetes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Nine non-stone-forming patients who had type 2 diabetes and low urine pH and 16 age- and body mass index-matched non-stone-forming volunteers without type 2 diabetes were maintained on a constant metabolic diet for 7 days, and 24-hour urine was collected on the last 2 days of the diet. RESULTS: Urine dietary markers (potassium, sulfate, phosphorus, and urea nitrogen) were not different between the two groups. Patients with type 2 diabetes exhibited a significantly lower 24-hour urine pH (5.45+/-0.27 versus 5.90+/-0.42; P<0.01) and higher net acid excretion (NAE; 57+/-12 versus 38+/-18 mEq/d; P<0.01) compared with control subjects. The proportion of NAE excreted as ammonium (NH4+/NAE) was significantly lower in patients with type 2 diabetes than in control subjects (0.70+/-0.12 versus 0.94+/-0.36; P<0.01); however, the greater NAE in patients with type 2 diabetes was not accounted for by the differences in unmeasured urinary anions. CONCLUSIONS: The overly acidic urine in patients with type 2 diabetes persists after controlling for dietary factors, body size, and age. The lower pH is due to a combination of greater NAE and lower use of ammonia buffers in patients with diabetes, which predisposes them to uric acid urolithiasis.
BACKGROUND AND OBJECTIVES:Type 2 diabetes is associated with excessively low urine pH, which increases the risk for uric acidnephrolithiasis. This study was conducted to assess the metabolic basis responsible for the excessive urinary acidity of individuals with type 2 diabetes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Nine non-stone-forming patients who had type 2 diabetes and low urine pH and 16 age- and body mass index-matched non-stone-forming volunteers without type 2 diabetes were maintained on a constant metabolic diet for 7 days, and 24-hour urine was collected on the last 2 days of the diet. RESULTS: Urine dietary markers (potassium, sulfate, phosphorus, and ureanitrogen) were not different between the two groups. Patients with type 2 diabetes exhibited a significantly lower 24-hour urine pH (5.45+/-0.27 versus 5.90+/-0.42; P<0.01) and higher net acid excretion (NAE; 57+/-12 versus 38+/-18 mEq/d; P<0.01) compared with control subjects. The proportion of NAE excreted as ammonium (NH4+/NAE) was significantly lower in patients with type 2 diabetes than in control subjects (0.70+/-0.12 versus 0.94+/-0.36; P<0.01); however, the greater NAE in patients with type 2 diabetes was not accounted for by the differences in unmeasured urinary anions. CONCLUSIONS: The overly acidic urine in patients with type 2 diabetes persists after controlling for dietary factors, body size, and age. The lower pH is due to a combination of greater NAE and lower use of ammonia buffers in patients with diabetes, which predisposes them to uric acidurolithiasis.
Authors: John C Lieske; Lourdes S Peña de la Vega; Matthew T Gettman; Jeffrey M Slezak; Eric J Bergstralh; L Joseph Melton; Cynthia L Leibson Journal: Am J Kidney Dis Date: 2006-12 Impact factor: 8.860
Authors: Mary Ann Cameron; Naim M Maalouf; Beverley Adams-Huet; Orson W Moe; Khashayar Sakhaee Journal: J Am Soc Nephrol Date: 2006-04-05 Impact factor: 10.121
Authors: Naim M Maalouf; Mary Ann Cameron; Orson W Moe; Beverley Adams-Huet; Khashayar Sakhaee Journal: Clin J Am Soc Nephrol Date: 2007-08-16 Impact factor: 8.237
Authors: I Alexandru Bobulescu; Naim M Maalouf; Giovanna Capolongo; Beverley Adams-Huet; Tara R Rosenthal; Orson W Moe; Khashayar Sakhaee Journal: Am J Physiol Renal Physiol Date: 2013-09-11
Authors: I Alexandru Bobulescu; Sun K Park; L H Richie Xu; Francisco Blanco; John Poindexter; Beverley Adams-Huet; Taylor L Davidson; Khashayar Sakhaee; Naim M Maalouf; Orson W Moe Journal: Clin J Am Soc Nephrol Date: 2019-02-11 Impact factor: 8.237
Authors: Paula Stettner; Soline Bourgeois; Christian Marsching; Milena Traykova-Brauch; Stefan Porubsky; Viola Nordström; Carsten Hopf; Robert Koesters; Robert Kösters; Roger Sandhoff; Herbert Wiegandt; Carsten A Wagner; Hermann-Josef Gröne; Richard Jennemann Journal: Proc Natl Acad Sci U S A Date: 2013-05-28 Impact factor: 11.205