Section of Nephrology, MD Anderson Cancer Center, Houston, TX, USA.
Math Biosci. 2018 Dec;306:97-106. doi: 10.1016/j.mbs.2018.05.010. Epub 2018 May 22.
Ascertaining a patient's kidney function is more difficult to do when the serum creatinine is changing than when it is stable. To accomplish the task, various kinetic clearance equations have been developed. To date, however, none of them have allowed for ongoing changes to the creatinine's volume of distribution. These diluting or concentrating effects on the [creatinine] can greatly impact the accuracy of kidney function assessment. Described herein is a model of creatinine kinetics that also accommodates volume changes. The differential equation is solved for the kinetic glomerular filtration rate (GFR), which is helpful information to the physician. Some of the equation's discontinuities, such as from dividing by a volume rate of zero, can be resolved by using limits. Being "volume-capable," the new kinetic equation reveals how a changing volume influences the maximum rate of rise in [creatinine], a parameter that heretofore was chosen empirically. To show the advantages of incorporating volume, the new and old kinetic equations are applied to a clinical case of overzealous fluid resuscitation. Appropriately, when the volume gain's dilution of [creatinine] is taken into account, the creatinine clearance is calculated to be substantially lower. In conclusion, the kinetic GFR equation has been upgraded to handle volume changes simultaneously with [creatinine] changes.
当血清肌酐发生变化时，确定患者的肾功能比稳定时更具挑战性。为了完成这项任务，已经开发出了各种动力学清除方程。然而，迄今为止，这些方程都没有考虑肌酐分布体积的持续变化。这些稀释或浓缩效应对[肌酐]的影响会极大地影响肾功能评估的准确性。本文描述了一种也可以适应体积变化的肌酐动力学模型。该微分方程用于求解动力学肾小球滤过率（GFR），这是医生的有用信息。该方程的一些不连续点，例如除以零体积率，可以通过使用极限来解决。新的动力学方程具有“体积能力”，可以揭示体积变化如何影响[肌酐]的最大上升速率，这是一个以前凭经验选择的参数。为了展示纳入体积的优势，将新的和旧的动力学方程应用于过度积极的液体复苏的临床病例。适当的是，当考虑到[肌酐]稀释的容量增加时，计算出的肌酐清除率要低得多。总之，动力学 GFR 方程已升级为同时处理[肌酐]变化和体积变化。
