Pro-atrial natriuretic peptide (ANP) according to severity of disease and circulating procalcitonin (PCT) levels. All patient data were grouped according to (a) the severity of the disease following consensus criteria ('no SIRS',' SIRS', 'sepsis', 'severe sepsis' and 'septic shock') or (b) circulating PCT concentrations. Data from all time points (i.e. on admission, day 2, day of discharge and death) are displayed. Solid lines denote median values, boxes represent 25th to 75th percentiles and whiskers indicate the range. ANOVA, analysis of variance.