PREVALENCE AND RENAL OUTCOMES OF NEPHROMEGALY IN CHILDREN WITH BILIARY ATRESIA BEFORE AND AFTER LIVER TRANSPLANTATION

PREVALENCE AND RENAL OUTCOMES OF NEPHROMEGALY IN CHILDREN WITH BILIARY ATRESIA BEFORE AND AFTER LIVER TRANSPLANTATION

Nephromegaly has been associated with infantile biliary atresia (BA), the most common indication for liver transplantation in children. Acute kidney injury (AKI) is an important co-morbidity impacting survival after liver transplantation. The prevalence and renal outcomes associated with nephromegaly before and after liver transplant are poorly understood. Our aim was to assess the prevalence of nephromegaly and acute kidney injury in BA patients and describe the evolution of kidney size post-liver transplant.

This was a retrospective cohort study of 86 patients with BA who underwent liver transplantation from 2011 to 2020 at the University of Miami/ Miami Transplant Institute. Patients were excluded if they did not have satisfactory baseline kidney imaging or had any congenital cardiac or kidney anomalies. Pre-transplant baseline estimated glomerular filtration rate (eGFR) was assessed by the modified Schwartz and Full Age Spectrum equations using serum creatinine (SCr) and/or cystatin C (CysC). AKI was defined using the modified KDIGO criteria for children. Total kidney volume (TKV) was calculated from the ellipsoid equation (length x width x anterior posterior (AP) diameter x (π/6)) pre- and post-liver transplantation. Nephromegaly (NM) was defined as TKV indexed to body surface area (BSA) greater than the 95th percentile =132 ± 31.3ml/m2 (z-score≥1.65) of the reference population.

Sixty-one patients met inclusion criteria with 39/61 (64%) female. The median age at liver transplant was 0.91 (0.72,1.70) years with an average follow-up of 6.6 ± 4.0 years. Five-year patient and graft survival was 97%. The pre-transplant TKV/BSA for the entire cohort was 229 (165, 256) ml/m2 compared to 186 ± 55 ml/m2 post-transplant and remained elevated above the general population (Figure 1). Baseline eGFR using the SCr-based formula was significantly higher than the FAS and CysC-based estimations (136±46 compared to 108±35 and 102±35ml/min/1.73m2, respectively; p<0.05). Nephromegaly occurred in 42/61 (69%) of BA patients with a non-significant higher trend in eGFR in the NM compared to no NM group. Time between the pre- and post-transplant imaging was 13 (7,21) months (n=55). A 49% decline post-transplant in TKV/BSA z-score was noted in the NM group compared to a 1.2% increase in the no NM group (Table 1). AKI occurred in 20/61 (33%) with 12/20 (60%) occurring post-transplant. AKI occurred regardless of NM status (14/42 (33%) NM versus 6/19 (32%) no NM; p=NS). The 3 patients that required kidney replacement therapy had full renal recovery.

Nephromegaly is highly prevalent in children with BA and persists after liver transplantation. Estimating GFR using non-SCr based formulae may be more appropriate in this population. While 1/3 of BA patients had AKI irrespective of nephromegaly status, full renal recovery was achieved, and overall patient mortality remained low. Future studies should focus on the pathophysiologic mechanisms and long-term renal outcomes in BA patients following liver transplantation.