Professor Stephen Marks, MD MSc MRCP DCH FRCPCH is Professor of Paediatric Nephrology and Transplantation at University College London Great Ormond Street Institute of Child Health and President of the British Association for Paediatric Nephrology. He is clinical lead for renal transplantation and Director of the National Institute for Health Research Great Ormond Street Hospital Clinical Research Facility at Great Ormond Street Hospital for Children NHS Foundation Trust. He has local, national and international roles including Chair of the Education Committee of the International Pediatric Transplant Association (IPTA) having also been an IPTA Councillor. His research continues to date in the fields of renal transplantation (including innovative drug trials concerning new anti-rejection therapies and assessment of children post-renal transplantation), systemic lupus erythematosus and vasculitis. He is on the editorial board for “Pediatric Nephrology” and “British Journal of Renal Medicine” and is associate editor for “Transplantation” and “Pediatric Transplantation”, which are the journals of The Transplantation Society (TTS) and the International Pediatric Transplant Association (IPTA), respectively.
Filtration fraction is higher in children post-kidney transplantation and associates with lower serum creatinine
Barian Mohidin1, Chris A Clark1, Stephen D Marks1,2.
1UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom; 2Paediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
Aims: Magnetic resonance imaging (MRI) using an arterial spin labelling technique uses protons from dissociated water molecules as an endogenous tracer. Tracking the movement of protons through a series of images allows estimation of renal blood flow (RBF). Measuring haematocrit and serum creatinine simultaneously, enables estimation of renal plasma flow (RPF), glomerular filtration rate (GFR) and filtration fraction. The latter represents the proportion of plasma that is filtered at the glomerulus. Haemodynamic changes and a lack of autoregulation may result in significant changes to the filtration fraction after kidney transplantation.
Methods: We aimed to measure filtration fraction in a prospective cohort of fourteen paediatric patients who received a kidney transplant for end-stage kidney disease. The cohort had standard of care follow-up monitoring as well as an additional renal allograft MRI scan at 2 weeks and 2, 6, 9, 12, and 36 months after kidney transplantation.
Results: Strong negative correlation was observed between serum creatinine and filtration fraction (r = -0.81 (95% CI -0.88, -0.72) p < 0.0001). No significant difference was detected in serum creatinine, RBF, RPF or filtration fraction between patients. The median RBF and serum creatinine remained stable throughout the follow-up period. The median filtration fraction was significantly higher in children post-transplantation compared to normal native kidneys. A higher filtration fraction was associated with higher estimated glomerular filtration rate and improved renal allograft function. No significant difference was detected in filtration fraction in patients who experienced rejection of their transplant during follow-up versus those who did not.
Conclusions: The estimated glomerular filtration rate was higher per ml/min of renal plasma flow in children with lower serum creatinine. This may represent glomerular hyperfiltration due to altered haemodynamics. It is unclear whether such glomerular hyperfiltration has adverse effects on long-term renal allograft outcomes.
[1] Filtration fraction
[2] Renal plasma flow
[3] Renal blood flow
[4] Glomerular filtration rate
[5] MRI Arterial Spin Labelling