Response to the letter about 'Development of a modified sampling and calculation method for isotope plasma clearance assessment of glomerular filtration rate in patients with cirrhosis and ascites'

摘要

Plasma clearance (or strictly speaking the plasma concentration weighted mean of plasma clearance) of Cr-51 EDTA is recommended in the BNMS Guidelines as the standard measure of glomerular filtration rate [1]. These measurements rely on the calculation of the area under the plasma concentration curve from the time of injection to infinity. This is more difficult if the individual has ascites. For most individuals, the plasma clearance after 2h can be approximated to a single terminal exponential. This allows the area under the curve to be calculated using the slope-intercept technique described in the guidelines. However, for individuals with ascites, the plasma clearance curve cannot be approximated to a single exponential after 2 h, and so the slope-intercept technique is not appropriate.