Abstract
Survival of patients in septic shock is related to both basal concentrations and stimulated total cortisol (TC) concentrations after synacthen. Adrenal insufficiency is associated with poor outcome. Free cortisol (FC) has been proposed to be a better indicator of adrenal function since low CBG and albumin concentrations could cause subnormal TC concentrations. We compared basal and stimulated concentrations of FC and TC pre- and post-low dose synacthen. Nine control subjects and eight patients with septic shock had blood samples taken at 0, 30 and 60 min after injection of 1 μg Synacthen. TC was measured by chemiluminescent assay (Bayer); FC by steady state gel filtration; CBG by manual RIA and albumin by BCP (Beckman). A FC index (cortisol/CBG) and calculated FC were determined. Adrenal function, using each of these parameters, was assessed and patients compared with controls using t-test. Deming regression was used for correlations between parameters. Two patients had higher TC concentrations at 0 and 30 min and one patient a subnormal level compared to normals. At 60 min six patients had TC levels above the normal levels. For FC, six of eight patients had basal levels above the normal range. All patients had a greater increase in FC at both 30 min and 60 min. Half the patients had higher levels at 60 min than 30 min. Measured and calculated FCs correlated well but there was no correlation with FC index in patients. The strongest correlation was between the cortisol/albumin ratio and FC. There was good correlation between basal TC and FC in patients but no correlation at 30 min and 60 min. Our data show that septic patients usually have FC levels above those of normal subjects. After synacthen stimulation all patients had greatly increased responses. This may indicate decreased metabolism of cortisol in septic patients. Results are being assessed against patient outcome.