The concentrations of platelet-derived growth factor in serum in 7 healthy controls (61 +/- 9 years; mean +/- SD) and 10 patients (62 +/- 8 years) with chronic liver disease (chronic hepatitis and/or liver cirrhosis) were compared. The plasma concentration of platelet-derived growth factor was below the detection limit (< 0.45 microgram/l) in all the subjects studied. The peripheral blood platelet count in patients with chronic liver disease was significantly lower than that in control subjects. However, the concentration of platelet-derived growth factor in serum, which was assumed to be released from platelet, was similar in patients with chronic liver disease and control subjects. These results indicate that the mean amount of platelet-derived growth factor released from the same number (10(9)) of platelets, calculated from the serum platelet-derived growth factor concentration and the peripheral blood platelet count, in patients with chronic liver disease (33 +/- 11 ng/10(9) platelets) was significantly (p < 0.01) higher than that in control subjects (14 +/- 5 ng/10(9) platelets). Moreover, the amount of platelet-derived growth factor released from 10(9) platelets inversely correlated with the serum concentration of pseudocholinesterase activity (r = -0.65, p < 0.01), and correlated positively (r = 0.91, p < 0.01) with the percent retention of indocyanine green in serum, in all subjects studied. These findings suggest that the amount of platelet-derived growth factor releasable from platelets of patients with chronic liver disease is higher than that in normal subjects and that it correlates with the severity of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)