Chamberlain M J, Stimmler L
J Clin Invest. 1967 Jun;46(6):911-9. doi: 10.1172/JCI105597.
The renal handling of insulin was studied by insulin immunoassay in arterial blood, renal venous blood, and urine of fasting patients with normal renal function and in peripheral venous blood and urine of normal subjects and patients with renal disease before and after an oral glucose load. A renal arteriovenous insulin concentration difference of approximately 29% was found and suggests that in normal subjects renal insulin clearance is significantly in excess of glomerular filtration rate. The insulin excreted in the urine of normal individuals at no time exceeded 1.5% of the load filtered at the glomerulus. This contrasts with the finding of a urinary insulin clearance approaching glomerular filtration rate in patients with severely impaired renal tubular function. It is suggested that insulin is normally filtered at the glomerulus and then almost completely reabsorbed or destroyed in the proximal tubule. If reabsorption occurs, as seems more likely, reabsorbed insulin does not return to the renal vein and is presumably utilized in renal metabolism together with insulin taken up directly from the blood. Caution is advised in the use of urinary insulin concentration or excretion as an index of serum insulin level or insulin secretion because a very small and variable proportion of filtered insulin appears in the urine in normal subjects, and major changes in urinary insulin excretion may arise as a result of minor tubular defects.
通过胰岛素免疫测定法，对肾功能正常的空腹患者的动脉血、肾静脉血及尿液，以及正常受试者和肾病患者口服葡萄糖负荷前后的外周静脉血及尿液中的胰岛素肾处理情况进行了研究。发现肾动静脉胰岛素浓度差约为29%，这表明在正常受试者中，肾胰岛素清除率显著超过肾小球滤过率。正常个体尿液中排出的胰岛素在任何时候都不超过肾小球滤过负荷的1.5%。这与肾小管功能严重受损患者尿胰岛素清除率接近肾小球滤过率的发现形成对比。提示胰岛素通常在肾小球滤过，然后在近端小管几乎完全被重吸收或破坏。如果发生重吸收，似乎更有可能的是，重吸收的胰岛素不会回到肾静脉，大概是与直接从血液中摄取的胰岛素一起用于肾脏代谢。在将尿胰岛素浓度或排泄量用作血清胰岛素水平或胰岛素分泌指标时应谨慎，因为在正常受试者中，滤过胰岛素仅有非常小且可变比例出现在尿液中，轻微的肾小管缺陷可能导致尿胰岛素排泄量发生重大变化。
