Aims An increase in transplant biopsy rate in the first month following renal transplantation (RT) was observed in our centre following implementation of an early steroid withdrawal (ESW) immunosuppression (IS) protocol in 2009. The aims of the study were to both investigate the frequency and findings of biopsies within the first month following RT and to assess the rate of acute rejection (AR) before and after the change in IS protocol.

Methods Retrospective record review of 98 consecutive transplants in 96 children between January 2007 and August 2013. Tacrolimus trough levels of 10–15 mcg/l were aimed for in the first 21 days and levels of 8–10 mcg/l from day 21 to 30 following RT. Indication for biopsy was a 20% rise in plasma creatinine in the absence of infection, dehydration, obstruction and high tacrolimus levels.

Results Sixty four percent of kidneys were from living donors. There were 33 children in the steroid group and 65 in the ESW group. 53 biopsies were carried out in the first month in 43 patients. Mean timing of biopsy was 13 days following RT. Eight children had AR, giving an AR rate of 9.2% (Banff Ia in 5, Ib 2 and IIa 1). Nine had biopsy changes consistent with acute tubular necrosis and seven had evidence of donor vascular disease. Mean eGFR peaked at 100 ml/min/1.73 m² on day 5 and decreased to 82 ml/min/1.73 m² by day 13 following RT. Mean tacrolimus trough level peaked at 11.8 mcg/l on day 10.

In the steroid group, 24% of patients had an early transplant biopsy, compared to 54% in the ESW group (p < 0.05). Tacrolimus levels were on average lower in the steroid group by 0.9 mcg/l (p < 0.05) when compared to the ESW group. There was no significant difference in eGFR or rejection rates between the two groups.

Conclusions Early RT biopsy rates have doubled since adopting an ESW protocol. However, AR rate has not increased. The drop in eGFR appears to coincide with peaking of tacrolimus level, suggesting that this might be related to calcineurin inhibitor toxicity.