A simple method for the quantification of portosystemic shunting (PSS) in patients with portal hypertension

Portosystemic shunting (PSS) was evaluated in 32 patients with chronic liver disease by the rectal administration of iodine-123 I-amphetamine (IMP method), a radionuclide which is rapidly absorbed from the sigmoid and extracted by liver and lungs. Simultaneous measurement of pulmonary and hepatic uptake supplies a shunt fraction (SF) as an index of PSS. The IMP method was compared with the ammonia tolerance test (NH3TT), and there proved to be a significant correlation between these two methods (r = 0.75, p < 0.001). Assuming that an increase of > 7 mumol/l in arterial ammonia concentration after NH3TT represents PSS, the IMP method had a sensitivity of 0.93. When fasting (NH3) was > 50 mumol/l, all patients showed pathological PSS with either method, but this was also the case in 50% of patients with normal basal arterial ammonia. There was also a significant correlation between the IMP method and the Child-Pugh classification (r = 0.75, p < 0.001). Endoscopy in 28 patients revealed absence of varices in 11, of whom, however, 7 (64%) had an increased SF and although all 15 patients with ascites had increased SF, this was also the case in 12 of the 17 patients without ascites. In conclusion, PSS evaluation using IMP is a non-invasive, sensitive method without patient discomfort which might be used in the staging and follow-up of chronic liver disease.