Helena McMeekin1, Mark Barnfield2, Fred Wickham3, Maria Burniston1. 1. Department of Nuclear Medicine, Barts Health NHS Trust, London. 2. Department of Nuclear Medicine, St James's University Hospital, Leeds. 3. Department of Nuclear Medicine, Royal Free London NHS Foundation Trust, London, UK.
Abstract
AIM: The study aimed to investigate whether a systematic difference exists between Cr EDTA and Tc DTPA for measurement of glomerular filtration rate (GFR). METHODS: The distribution of GFR results from candidates attending the Royal Free Hospital for assessment of suitability for kidney donation was compared before and after the change from Cr EDTA to Tc DTPA using three-sample slope-intercept GFR calculation with samples at 2, 3, and 4 hours. A second cohort of oncology patients attending Leeds Teaching Hospitals NHS Trust underwent simultaneous GFR measurement with both tracers by full characterisation of the plasma clearance curve with nine samples between 5 minutes and 8 hours post-injection. Three-sample slope-intercept GFR was also calculated for comparison with cohort 1. RESULTS: From the first cohort, a statistically significant (P = 0.008) systematic difference of 5.8% (95% confidence interval: 1.5%-10.1%) was found in the three-sample slope-intercept GFR, with Tc DTPA giving the higher result. From the second cohort, a statistically significant (P = 0.00001) systematic difference of 2.9% (95% confidence interval: 1.8%-3.9%) was found in three-sample slope-intercept GFR, with Tc DTPA giving the higher result. There was no statistically significant difference between the tracers when GFR was calculated by full characterisation of the plasma clearance curve. CONCLUSION: There is a small systematic difference between GFR measured with Tc DTPA and Cr EDTA using abbreviated techniques, which is removed when GFR is calculated by full characterisation of the plasma clearance curve. The difference is not clinically significant in the context of intra-patient variability of GFR measurement.
AIM: The study aimed to investigate whether a systematic difference exists between Cr EDTA and Tc DTPA for measurement of glomerular filtration rate (GFR). METHODS: The distribution of GFR results from candidates attending the Royal Free Hospital for assessment of suitability for kidney donation was compared before and after the change from Cr EDTA to Tc DTPA using three-sample slope-intercept GFR calculation with samples at 2, 3, and 4 hours. A second cohort of oncology patients attending Leeds Teaching Hospitals NHS Trust underwent simultaneous GFR measurement with both tracers by full characterisation of the plasma clearance curve with nine samples between 5 minutes and 8 hours post-injection. Three-sample slope-intercept GFR was also calculated for comparison with cohort 1. RESULTS: From the first cohort, a statistically significant (P = 0.008) systematic difference of 5.8% (95% confidence interval: 1.5%-10.1%) was found in the three-sample slope-intercept GFR, with Tc DTPA giving the higher result. From the second cohort, a statistically significant (P = 0.00001) systematic difference of 2.9% (95% confidence interval: 1.8%-3.9%) was found in three-sample slope-intercept GFR, with Tc DTPA giving the higher result. There was no statistically significant difference between the tracers when GFR was calculated by full characterisation of the plasma clearance curve. CONCLUSION: There is a small systematic difference between GFR measured with Tc DTPA and Cr EDTA using abbreviated techniques, which is removed when GFR is calculated by full characterisation of the plasma clearance curve. The difference is not clinically significant in the context of intra-patient variability of GFR measurement.
Authors: A Samani; R Bennett; K Eremeishvili; F Kalofonou; S Whear; A Montes; R Kristeleit; J Krell; I McNeish; S Ghosh; L Tookman Journal: ESMO Open Date: 2022-02-26