Absolute 24 h quantification of Tc-99(m)-DMSA uptake in patients with severely reduced kidney function: A comparison with Cr-51-EDTA clearance

The aim of this study was to determine whether absolute 24 h DMSA uptake me asurements (%DMSA) correlate well with Cr-51-EDTA clearance measurements in patients with severely reduced kidney function (SRKF). Between 1990 and 19 97, 55 of 482 patients who underwent EDTA clearance measurements also under went %DMSA within 1 week. Of these, 31 were women and 24 were men (mean age 60 years; range 19-77 years). EDTA clearance was determined using the slop e-intercept method. Absolute depth- and background-corrected % DMSA were de termined 24 h following the injection of 185 MBq per 1.73 m(2) freshly prep ared Tc-99(m)-DMSA. All patients had EDTA clearance less than or equal to 6 0 ml . min(-1). Eighteen patients (group A: 9 men and 9 women, mean age 55. 8 years, range 28-73 years) had EDTA clearance > 20 ml . min(-1) (mean +/- S.D. = 30.9 +/- 13.8 ml . min(-1)), whereas 37 patients (group B: 22 women and 15 men, mean age 62.0 years, range 19-77 years) had EDTA clearance < 20 ml . min(-1) (mean +/-: S.D. = 10.2 +/- 6.6 ml . min(-1)). EDTA clearance correlated well with %DMSA for the patients as a whole and for group A (r = 0.87, P = 0.73; r = 0.79, P = 0.0001 respectively). The regression equatio n suggests that %DMSA is not a marker of early renal dysfunction. In group B, the r-value (r = 0.48, P = 0.004) suggests that %DMSA is reliable as a m arker of severe renal dysfunction to the extent that ii provides rough info rmation. In conclusion, %DMSA may not be used as a marker of early renal im pairment. Additionally, in patients with severly reduced kidney function (E DTA clearance < 20 ml . min(-1)), it only provides a rough estimate. ((C) 1 999 Lippincott Williams & Wilkins).