Carr S, Mbanya J C, Thomas T, Keavey P, Taylor R, Alberti K G, Wilkinson R
Department of Medicine, Freeman Hospital, Newcastle upon Tyne, United Kingdom.
N Engl J Med. 1990 Feb 22;322(8):500-5. doi: 10.1056/NEJM199002223220803.
Increased sodium-lithium countertransport in erythrocytes is found in patients with insulin-dependent diabetes mellitus (IDDM) and nephropathy. To determine whether such an increase precedes the onset of nephropathy and, if so, whether it is associated with changes in renal function, we measured erythrocyte sodium-lithium countertransport in 52 patients with IDDM but not nephropathy or hypertension and in 32 control subjects. Seventeen of the 52 patients with IDDM (33 percent) had sodium-lithium countertransport activity that exceeded the maximal activity in the control subjects (0.39 mmol of lithium per hour per liter of cells). Eighteen of the 52 patients with IDDM were studied in more detail. The 7 patients with raised sodium-lithium countertransport values had glomerular filtration rates (median, 159 ml per minute per 1.73 m2 of body-surface area; range, 134 to 197) that were significantly higher (P less than 0.01) than those in the remaining 11 patients with IDDM and normal sodium-lithium countertransport (median, 126 ml per minute per 1.73 m2; range, 110 to 176) or in the 10 control subjects (median, 128 ml per minute per 1.73 m2; range, 93 to 151). In the seven patients with elevated sodium-lithium countertransport, the filtration fraction (median, 0.27; range, 0.22 to 0.37) was also greater (P less than 0.01) than that in control subjects (median, 0.22; range, 0.18 to 0.28). There were no differences in renal function between the patients with IDDM and normal sodium-lithium countertransport and the control subjects. We conclude that sodium-lithium countertransport is increased in patients with IDDM before the onset of nephropathy and is associated with hyperfiltration. Thus, elevated sodium-lithium countertransport activity may be an early marker of diabetic nephropathy.
胰岛素依赖型糖尿病（IDDM）患者及肾病患者红细胞中的钠-锂逆向转运增加。为了确定这种增加是否先于肾病的发生，如果是，它是否与肾功能变化相关，我们对52例无肾病或高血压的IDDM患者及32例对照者的红细胞钠-锂逆向转运进行了测量。52例IDDM患者中有17例（33%）的钠-锂逆向转运活性超过了对照者的最大活性（每升细胞每小时0.39毫摩尔锂）。对52例IDDM患者中的18例进行了更详细的研究。钠-锂逆向转运值升高的7例患者的肾小球滤过率（中位数为每1.73平方米体表面积每分钟159毫升；范围为134至197）显著高于（P<0.01）其余11例钠-锂逆向转运正常的IDDM患者（中位数为每1.73平方米每分钟126毫升；范围为110至176）或10例对照者（中位数为每1.73平方米每分钟128毫升；范围为93至151）。在钠-锂逆向转运升高的7例患者中，滤过分数（中位数为0.27；范围为0.22至0.37）也高于（P<0.01）对照者（中位数为0.22；范围为0.18至0.28）。钠-锂逆向转运正常的IDDM患者与对照者之间的肾功能无差异。我们得出结论，IDDM患者在肾病发生前钠-锂逆向转运增加，且与超滤过相关。因此，钠-锂逆向转运活性升高可能是糖尿病肾病的早期标志物。
