99mTc-HEPIDA plasma clearance as a diagnostic tool. Total plasma v. specific hepatic clearance.

BACKGROUND: (99m)Tc-HEPIDA total plasma clearance has been used for assessment of hepatic parenchyma damage. However, the radiopharmaceutical used is being partly cleared from plasma also by the urinary tract. As the share of the latter route in total elimination of the compound is not well known, the aim of the study was to investigate the percentage of (99m)Tc-HEPIDA eliminated by the kidneys and by the liver. MATERIAL AND METHODS: To this aim total plasma clearance of the compound and urinary part were determined by the methods employed here in 117 patients and in 16 healthy volunteers. The pure hepatic clearance was calculated as the difference between total plasma and the urinary clearance of (99m)Tc-HEPIDA. RESULTS: The urinary clearance in patients amounted from 2.6 to 78% of total clearance; in the healthy volunteers the corresponding range was from 8.6 to 28%. Pronounced spread of the urinary clearance (coefficient of variation = 35%) and lack of correlation between the urinary and total clearance make it necessary to take account of urinary elimination in each patient in whom reasonably accurate assessment of hepatic clearance is required. CONCLUSION: Further studies on the diagnostic efficacy of pure hepatic clearance and its change with age in healthy patients appear necessary.