Electron microscopy in determining the etiology of kidney allograft dysfunction.

BACKGROUND: Biopsy of the transplanted kidney serves a definitive role in elucidating the possible causes of allograft dysfunction. At our transplant clinic we have observed that electron microscopy (EM) does not usually refine the findings initially disclosed by light microscopy with direct immunofluorescence (LM). METHODS: We studied whether EM results differ from or add to LM results. We compared the reports of 65 allograft biopsies performed on 60 patients over 82 consecutive weeks. We classified biopsy interpretations by 15 possible diagnoses and categorically by glomerular versus nonglomerular disease. We determined agreement between LM and EM reports by Cohen's kappa statistic, and applied the McNemar test to determine whether EM interpretation yielded significantly more glomerular diagnoses on the same biopsy samples. RESULTS: There was strong agreement (kappa, 0.94: 95% confidence interval [CI], 0.88-1.00), between the EM- and LM-based interpretations. EM did not detect more glomerular disease than LM (discordance rate, 4.6%: 95% CI, -1.92% to 4.62%: P = .25). EM did not add to the diagnosis of rejection. EM described 3 additional cases of transplant glomerulopathy, but did not lead in a change in management of kidney allograft dysfunction. CONCLUSION: Electron microscopy, used routinely, does not add to light microscopy in the evaluation of kidney transplant dysfunction.

The utility of cytodiagnostic urinalysis as a tool to diagnose kidney allograft dysfunction in the era lymphocyte-depleting induction therapy.

Cytodiagnostic urinalysis (CDU) has been used to evaluate causes of kidney allograft dysfunction, such as an acute rejection episode (ARE), calcineurin inhibitor (CNI) toxicity, or polyoma virus infection. We examined the concordance between CDU and allograft biopsy in patients with allograft dysfunction. Between 2002 and 2006, 201 patients had CDU performed within 7 days of a biopsy. The cohort was black (73%) with, male preponderance (59.2%), and an overall mean age of 48±13 years with 46% having received a deceased donor kidney. The induction regimen consisted of either antithymocyte globulin or alemtuzumab. CDU results that demonstrated 5 to 10 lymphocytes per high-power field (HPF) and >20 lymphocytes/HPF had 2.5 increased odds of predicting acute rejection (AR) on biopsy (odds ratio [OR] 2.5; 95% confidence interval [CI] 1.12-5.79; P=.025). In the era of antithymocyte globulin induction, a CDU result demonstrating>5 lymphocytes/HPF had a 4.3 increased odds of predicting AR (CI 1.76-10.50; P=.001). This association was lost with alemtuzumab induction. A positive CDU result for calcineurin inhibitor (CNI) toxicity did not predict CNI nephrotoxcity on biopsy, but a positive CDU for polyoma virus infection predicted polyoma virus nephropathy (OR 22.18; CI: 4.41-111.63; P<.001). In conclusion, CDU is an adjunctive diagnostic tool for kidney transplantation.