Smith Cynthia R, Poindexter John R, Meegan Jennifer M, Bobulescu Ion Alexandru, Jensen Eric D, Venn-Watson Stephanie, Sakhaee Khashayar
National Marine Mammal Foundation, San Diego, California.
Department of Internal Medicine and Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas.
J Urol. 2014 Jul;192(1):260-6. doi: 10.1016/j.juro.2014.01.008. Epub 2014 Feb 8.
Nephrolithiasis is increasingly reported in bottle-nosed dolphins. All cases to date have been ammonium urate nephrolithiasis.
A case-control study was performed in dolphins with and without evidence of nephrolithiasis to identify biomarkers and risk factors associated with stone formation in a managed population. Dolphins were sampled in fasting and postprandial states to study the effect of dietary factors on serum and urinary biochemistry. Urine was continuously collected for 6 hours via catheter and divided into 3, 2-hour collections with a bolus fish meal given after completing the first collection. Blood was sampled at the beginning of the fasting period and the end of the postprandial period.
There were no significant differences in serum and urine chemistry or acid-base profiles between dolphins with vs without stones at baseline or postprandially. This suggests that cases and controls represent a continuum of stone risk. On analysis combining cases and controls in a single cohort we noted significant postprandial increases in urinary uric acid, sulfate and net acid excretion accompanied by increased urinary ammonium excretion and a commensurate increase in urine pH. The supersaturation index of ammonium urate increased more than twofold postprandially.
These findings suggest that dolphins are susceptible to ammonium urate nephrolithiasis at least in part because a high dietary load of acid and purines results in a transient but marked increase in the urinary supersaturation of the sparingly soluble ammonium urate salt.
瓶鼻海豚患肾结石的报道日益增多。迄今为止，所有病例均为尿酸铵肾结石。
对有和无肾结石证据的海豚进行病例对照研究，以确定与圈养种群中结石形成相关的生物标志物和风险因素。在禁食和餐后状态下对海豚进行采样，以研究饮食因素对血清和尿液生化指标的影响。通过导管连续收集尿液6小时，并将其分为3个2小时的收集样本，在完成第一次收集后给予一次大量鱼粉。在禁食期开始时和餐后结束时采集血液样本。
有结石和无结石的海豚在基线或餐后时血清和尿液化学指标或酸碱谱无显著差异。这表明病例和对照代表了结石风险的连续体。在将病例和对照合并为一个单一队列进行分析时，我们注意到餐后尿酸、硫酸盐和净酸排泄量显著增加，同时尿铵排泄量增加，尿液pH值相应升高。餐后尿酸铵的过饱和指数增加了两倍多。
这些发现表明，海豚易患尿酸铵肾结石，至少部分原因是高酸和嘌呤饮食负荷导致微溶性尿酸铵盐的尿液过饱和度短暂但显著增加。
