Dorizzi R M, Caputo M
Laboratorio Analisi Chimico Cliniche ed Ematologiche, Azienda Ospedaliera di Verona, Italy.
Clin Chem Lab Med. 1998 Dec;36(12):925-8. doi: 10.1515/CCLM.1998.160.
The relative density of urine is the ratio of its density to that of water and depends on both the number and weight of solute particles in the sample, while osmolality depends only on the number of solute particles. Water metabolism is regulated by the interaction of the renal medullary countercurrent system with the circulating levels of antidiuretic hormone and thirst. The concentration of solids in urine can be measured by weighing, hydrometry, oscillations of a capillary tube, refractometry and reagent strip. These techniques, interrelated but not identical, are commonly used in hospital laboratories and in clinical wards. We compared the results obtained in 1725 urine samples of inpatients and outpatients using an automated refractometer to those obtained using two visually read dip stick tests. The correlation coefficients (Super Aution analyser vs. Aution Sticks 10EA, Aution Sticks 10 EA vs. N-Multistix, Super Aution analyser vs. N-Multisticks were 0.663, 0.645 and 0.514, respectively) and the great dispersion of mountain plots demonstrates that different techniques are not interchangeable in the measurement of relative density. Since the results obtained after discarding the samples with pH higher than 7 and those containing glucose or protein were very similar to the ones reported above, the role of these interferents appears negligible in inducing the discrepancy.
尿液的相对密度是其密度与水的密度之比，取决于样本中溶质颗粒的数量和重量，而渗透压仅取决于溶质颗粒的数量。水代谢受肾髓质逆流系统与抗利尿激素循环水平及口渴感之间相互作用的调节。尿液中固体物质的浓度可通过称重法、液体比重测定法、毛细管振荡法、折射测定法和试剂条法来测量。这些技术相互关联但并不相同，常用于医院实验室和临床病房。我们将1725份住院患者和门诊患者尿液样本使用自动折射仪得到的结果与使用两种目视读取的试纸条测试得到的结果进行了比较。相关系数（超级自动分析仪与奥田试纸10EA、奥田试纸10EA与N-多联试纸、超级自动分析仪与N-多联试纸分别为0.663、0.645和0.514）以及散点图的较大离散度表明，在相对密度测量中不同技术不可互换。由于丢弃pH高于7以及含有葡萄糖或蛋白质的样本后得到的结果与上述结果非常相似，这些干扰物在导致差异方面的作用似乎可以忽略不计。
