Possibilities and pitfalls of indium-111 platelet scintigraphy in the monitoring of renal transplant recipients.

During the last four years, we have performed two studies on the clinical application of 111In-platelet scintigraphy after renal transplantation. In the first study, we collected 75 patients who were treated with prednisolone and azathioprine. The platelet deposition in the graft was expressed as a platelet-uptake index (PUI). The results suggested that the platelet scan was a valuable tool for early detection of acute graft rejection, which was indicated by an increase in PUI. Quite different results were obtained in 50 patients immunosuppressed with cyclosporin A (CSA) and prednisolone. Acute interstitial rejection escaped detection by this diagnostic procedure. Significant elevations of PUI were observed in acute vascular rejection and microvascular CSA nephrotoxicity, resembling the haemolytic uraemic syndrome (HUS) only. Therefore, platelet deposition in the graft can be regarded as a non-specific phenomenon, occurring in two entities which require completely different therapeutic approaches. In spite of the monitoring by means of the platelet scan, percutaneous biopsy is still necessary for differential diagnosis of graft dysfunction.