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Combined liver–kidney transplantation for hyperoxaluria type II?

In this edition of Pediatric Transplantation, Naderi et al. (1) published an unusual case of endstage renal disease (ESRD) in a relatively young patient with primary hyperoxaluria (PH) type II. Although the patient was considered for an isolated kidney transplant, the standard of care for this condition, evidence suggesting immediate recurrence and subsequent graft loss was found (2). Thus, as is common practice in PH type I, the authors question whether combined liver transplantation should also be considered for PH type II. In PH type I, the excessive production of oxalate will continue as long as the native liver is in situ because the liver is the sole organ responsible for glyoxylate detoxification (2). Consequently, it is well established that isolated kidney transplantation in PH type I is associated with a high rate of recurrence and graft loss (3). While pre-emptive liver transplantation is considered to avoid the complications of systemic oxalosis (4), PH I follows a heterogeneous clinical course and properly timing of the liver transplant in relation to the kidney function and to avoid further kidney damage remains challenging. Thus, most centers opt for combined or sequential liver and kidney transplantation. Although this has become standard of care and can yield excellent results in PH type I (5), there is no experience with combined liver and kidney transplantation in patients with PH type II. Type II PH originates from a different mutation and the ubiquitous tissue distribution of the resultant enzyme deficiency favors isolated kidney transplantation (2, 6). It should be noted that there have been case reports detailing oxalaterelated graft loss in patients with PH type II (7). This accompanying editorial aims to review current knowledge surrounding the three PHs and to discuss the feasibility of a combined liver– kidney transplant for this particular case, and was prompted by the possible link between the case presented by Dr. Naderi’s group and excessive oxalate burden prior to the transplantation. This editorial will summarize what is known about the three PHs, discuss management during dialysis, and will outline the supporting and opposing rationale for combined liver–kidney transplantation.