Diagnosis of pancreatic allograft rejection by measurement of urinary radioimmunoreactive insulin

Pancreas transplant: recent advances and spectrum of features in pancreas allograft pathology

As result of improved surgical techniques and newer immunosuppressive regimens contributing significantly to better graft survival, exocrine pancreas transplantation remains the standard treatment of choice for patients with diabetes mellitus complicated by end-stage renal disease. Histologic assessment continues to play an important role in the diagnosis of graft complications after pancreas transplantation, especially for evaluating allograft rejection where histopathology is still considered the gold standard. This review elaborates on the current types of pancreas transplants and focuses on the patterns of allograft injury that are encountered in posttransplantation pancreas biopsies along with the pertinent differential diagnoses. In addition to optimal histologic assessment, as in any other organ transplant setting, clinical information including indication and duration of transplant as well as other serologic work-up must be taken into consideration during clinical decision making for optimal graft outcome.

Are there still roles for exocrine bladder drainage and portal venous drainage for pancreatic allografts?

PURPOSE OF REVIEW

Controversy remains regarding the best methodology of handling exocrine pancreatic fluid and pancreatic venous effluent. Bladder drainage has given way to enteric drainage. However, is there an instance in which bladder drainage is preferable? Also, hyperinsulinemia, as a result of systemic venous drainage (SVD), is claimed to be proatherosclerotic, whereas portal venous drainage (PVD) is more physiologic and less atherosclerotic.

RECENT FINDINGS

Bladder drainage remains a viable method of exocrine pancreas drainage, but evidence is sparse that measuring urinary amylase has a substantial benefit in the early detection of acute rejection in all types of pancreas transplants. Currently, there is no incontrovertible evidence that systemic hyperinsulinemia is proatherosclerotic, whereas recent metabolic studies on SVD and PVD showed that there was no benefit to PVD.

SUMMARY

Given the advent of newer immunosuppressive agents and overall lower acute rejection rates, the perceived benefit of bladder drainage as a means to measure urinary amylase as an early marker of rejection has not been substantiated. However, there may be a selective role for bladder drainage in 'high risk' pancreases. Also, without a clear-cut metabolic benefit to PVD over SVD, it remains the surgeon's choice as to which method to use.

Early diagnosis and treatment of pancreas allograft rejection

A major problem in vascularized pancreas transplantation is the lack of reliable methods for the early diagnosis and effective treatment of allograft rejection. Over a 2-year period, 54 rejection episodes occurred in 31 patients (13 isolated pancreas, 18 simultaneous pancreas-kidney recipients) with pancreaticoduodenocystostomy. A total of 253 radionuclide pancreas examinations were performed (mean 8.4 per patient) utilizing 99mtechnetium-DTPA. Computer analysis generated a quantitative measure of blood flow to the allograft caused the technetium index (TI). Rejection episodes were characterized as isolated pancreas (22), combined pancreas-kidney (16), or isolated renal (16) allograft rejection in combined engraftments. The majority of rejection episodes occurred early (within 3 months of transplant, N = 47) and were more responsive than late rejection to anti-rejection therapy (89.4% vs 42.9%, P = 0.01). Mean urinary amylase (UA) levels and TI during normal allograft function were 29,398 U/l and 0.55%, while levels heralding rejection were 6,528 U/l and 0.40%, respectively (P less than 0.05). The treatment of rejection based upon renal dysfunction or combined renal and pancreas dysfunction resulted in significantly higher graft salvage with a lower incidence of hyperglycemia when compared to isolated pancreas allograft rejection. Of the 11 patients who developed hyperglycemia, 8 (72.7%) ultimately lost their pancreas grafts (P less than 0.001). Following therapy, a TI above 0.3% was associated with 97.4% graft survival, while levels below 0.3% resulted in a 70% rate of graft loss (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)