Asplin J, Parks J, Lingeman J, Kahnoski R, Mardis H, Lacey S, Goldfarb D, Grasso M, Coe F
Renal Section, University of Chicago, Illinois, USA.
J Urol. 1998 Jun;159(6):1821-5. doi: 10.1016/S0022-5347(01)63164-1.
We determined the validity of urine supersaturation assessed from 2, 24-hour urine collections from outpatients eating uncontrolled diets and receiving care at a network of treatment sites that uses a central laboratory. We compared supersaturation to stone composition to determine whether supersaturation values correlate with composition.
Two 24-hour urine samples collected from 183 patients at 6 treatment sites were shipped to a single central laboratory. Complexations and crystallizations in vitro from aging during the transport step were interrupted by pH change in acid and alkaline directions. Relevant analytes were measured, and supersaturation was calculated for calcium oxalate, calcium phosphate as brushite and uric acid. Stone analysis was done at various laboratories.
Urine supersaturation values correlated well with stone composition. Higher calcium phosphate and uric acid supersaturation was noted when stones contained higher amounts of calcium phosphate and any uric acid, respectively. In a validation study values of relevant urine materials were unchanged after 48 hours of aging.
Despite the need for sample transport, resulting in the inevitable aging of samples, and variations in diet and details of sample collection, supersaturation values measured in only 2, 24-hour urine collections accurately reflected stone composition. This finding indicates that supersaturation values are reasonably stable in most patients during the months to years required for stones to form. In addition, samples collected in standard practice settings and sent to a central laboratory may accurately reflect these supersaturation values.
我们确定了通过收集门诊患者两份24小时尿液来评估尿液过饱和度的有效性，这些患者饮食不受控制，在一个使用中央实验室的治疗点网络接受治疗。我们将过饱和度与结石成分进行比较，以确定过饱和度值是否与成分相关。
从6个治疗点的183名患者收集的两份24小时尿液样本被送往同一个中央实验室。在运输过程中，通过在酸性和碱性方向改变pH值来中断因老化导致的体外络合和结晶。测量相关分析物，并计算草酸钙、磷酸氢钙（以透钙磷石形式）和尿酸的过饱和度。结石分析在多个实验室进行。
尿液过饱和度值与结石成分相关性良好。当结石分别含有较高量的磷酸钙和任何尿酸时，观察到较高的磷酸钙和尿酸过饱和度。在一项验证研究中，相关尿液物质的值在老化48小时后没有变化。
尽管需要运输样本，导致样本不可避免地老化，以及饮食和样本收集细节存在差异，但仅通过收集两份24小时尿液测量的过饱和度值准确反映了结石成分。这一发现表明，在结石形成所需的数月至数年时间里，大多数患者的过饱和度值相当稳定。此外，在标准实践环境中收集并送往中央实验室的样本可能准确反映这些过饱和度值。
