Mercaptoacetyltriglycine diuretic renography and output efficiency measurement in renal transplant patients

Suspected urinary tract obstruction following renal transplantation present s a diagnostic dilemma. The purposes of this study were: (1) to establish a normal range of measurement of output efficiency (OE) in the renal transpl ant population, and (2) to assess prospectively the usefulness of OE in the setting of allograft obstruction. Twenty-two renal transplant patients wit h stable renal function and no evidence of hydronephrosis on serial ultraso und examination had a diuretic mercaptoacetyltriglycine scan with calculati on of OE. Three renal transplant patients with confirmed graft obstruction were also studied. Standard qualitative and quantitative parameters as well as OE were calculated. The mean OE for the 22 normal renal transplant pati ents was 86.3%+/-3.7% (range: 77%-91%). OE values in the three obstructed p atients were 59%, 68% and 75% respective ly, It is concluded that OE should normally exceed 77% in renal graft recipients. OE is a promising means of diagnosing functional obstruction in these patients.