Transcapillary escape rate of albumin positively correlates with plasma albumin concentration in acute but not in chronic inflammatory disease

Abstract

The relationship among “negative” plasma acute-phase proteins (APP), ie, albumin, prealbumin, and transferrin, and “positive” APP, ie, C-reactive protein (CRP), fibrinogen, and orosomucoid, was investigated in patients with acute infectious disease (n = 8) and in patients with chronic malignant disease (n = 9). In addition, the transcapillary escape rate (TER) and outflux (J alb) of albumin were investigated using an intravenous injection of 2 μCi 125I-albumin. Interleukin-6 (IL-6) plasma concentrations were measured with an enzyme immunoassay. In the majority of patients, negative APP were decreased, whereas positive APP were increased. However, in patients with infectious disease, there were no significant correlations between any of the negative and positive APP. Also, in patients with infectious disease, TER was increased to 8.6 ± 3.4 %/h (mean ± SD), and J alb to 114 ± 60 mg/kg/h, compared with normal values of 4.3 ± 2.6 %/h and 108 ± 7 mg/kg/h, respectively. Unexpectedly, there was a significant positive correlation between plasma albumin and both TER ( r = .8279, P = .011) and J alb ( r = .8683, P = .005). In patients with malignomas, significant correlations within negative and positive APP and inverse correlations between negative and positive APP resulted. Malignant disease induced only a slight elevation in TER (6.6 ± 2.4 %/h), J alb was within normal limits (92 ± 35 mg/kg/h), and no correlations between plasma albumin concentrations and TER ( r = −.0174, P = .97) or J alb ( r = .4090, P = .27) were found. IL-6 concentrations were increased in all patients with infectious disease (n = 8; 160 ± 260 pg/mL), but only in five of nine patients with malignomas (24 ± 54 pg/mL). The present data indicate that (1) the pattern of changes in plasma concentrations of APP differs substantially between patients with infectious disease and those with malignant tumors; and (2) although TER is increased, the positive correlation between plasma albumin concentration and TER strongly suggests that mechanisms other than TER contribute to hypoalbuminemia in the acute-phase response (APR).