Background: Sepsis is one of the most important causes of mortality in severely ill ICU patients. At least, a part of high mortality rate in sepsis patients is due to less specific clinical symptoms for prompt diagnosis. Recently some studies report that serum levels of procalcitonin will increase in these patients but changes of serum levels following treatments is not known. This study was designed to determin procalcitonin levels in patients with bacterial infectious disease in ICU, initially and during therapy and compare the levels during response to treatment.

Results: Thirty five patients, 22(62.9 %) men and 13(37.1%) women, were enrolled in this study. 18(51.4%) patients died. Procalcitonin level in most patients in admission day was more than 10 ng/ml [16 (45.7%)] but in patients that react to treatment, decline to lower than 0.5 ng/ml [14(77.8%)]. Mean rank of procalcitonin level from 1.14 ng/ml in first day reached to 2.72 ng/ml in seventh day (p<0.0001).