Clinical expression and long-term outcomes of primary hyperoxaluria types 1 and 2

Primary hyperoxaluria, types 1 and 2, are rare disorders. Much of the information in the literature has been derived from case reports and data registries limited to patients requiring dialysis and/or transplantation. We present a single-center experience of 42 patients and 437 patient years of clinical experience with primary hyperoxaluria. Median age at onset of symptoms for patients with type 1 PH was 9 years, type 2 15.7 years. Sixty-four percent of the patients were less than 15 years of age at onset of symptoms. There was no correlation between urine oxalate excretion rates and age at onset of symptoms. Stone forming activity was greater in patients with type 1 PH than type 2. Ten patients presented initially with ESRD, and an additional seven developed ESRD during the course of follow-up. ESRD occurred in 54 percent of the patients with type 1 and 12 percent of patients with type 2 PH. Eight patients received nine renal allografts, five patients received combined kidney/liver transplants, and one patient received a hepatic allograft only. Ten of the transplanted patients were surviving at the time of the most recent follow up. Eight of them have functioning renal grafts and four have functioning hepatic grafts. There have been no deaths since 1988 among the 32 patients followed since that time. These data may suggest a broad range of clinical expression of primary hyperoxaluria. With current management strategies, outcomes are more favorable than has been reflected in previous literature.