1 University Children's Hospital Zurich Switzerland 2 University Children's Hospital Hamburg Germany
Sir,
We read with great interest the paper by Ellis et al. [1], reporting their experience with six children undergoing combined liver-kidney transplantation for primary hyperoxaluria type 1 (PH1). Although the median time on dialysis was only 1 year and 4 months (range between 0 to 2 years and 2 months) outcome was unsatisfactory with two deaths and recurrence of oxalate deposits in all kidney grafts leading to organ loss in one child. This is in contrast to data from the European Oxalosis Registry [2], where patient and graft survival in patients with PH1 after combined liver-kidney transplantation was superior in those less than 2 years of end-stage renal disease (ESRD). The report by Ellis et al. strongly suggests that young children, and especially infants with ESRD due to PH1, may do far worse.
We fully support the authors conclusion, namely that avoiding ESRD by pre-emptive liver transplantation, is a potentially promising therapeutic strategy. Although the timing of this transplantation procedure remains controversial, our own short- [3] and long-term follow up [4] data of four children with PH1 after pre-emptive liver transplantation are encouraging. Patient survival is 100% after a median of 4.5 years at present and renal function could be preserved in all and even improved in one patient, where nephrocalcinosis completely disappeared. In one girl, who received the liver transplant at the age of 9.8 years at a glomerular filtration rate (calculated according to the Schwartz formula) of 27 ml/min/1.73 m2, creatinine clearance has remained stable at 25 ml/min/1.73 m2 for more than 6 years. Importantly, however, systemic oxalate production has also been stopped in this patient, so that in a future renal transplant, recurrence of oxalate disposal will not occur, thus improving long-term prognosis. On the other hand, this example clearly shows that pre-emptive liver transplantation should not be delayed for too long in a patient with declining renal function due to PH1, since function may not recover completely.
If ESRD has been reached, and this is in accordance with the conclusion of Ellis et al., early combined or sequential liver-kidney grafting is to be advocated before oxalate disposal (mainly in the bone) occurs. Improvements with splitting techniques [5] have resulted in the possibility of living related liver transplantation not only in children but also adolescents and even in adults, so that planning of pre-emptive or combined liver transplantation for PH1 becomes easier, minimizing the potential risks of oxalate deposition during ESRD.
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