diagnostic performance, with 74.4% and 93.7% sensitivity and 86.7% and 75.2% specificity among sepsis and severe sepsis/septic shock patients, respectively. PCT, IL-6, and CRP levels were significantly increased in non-survivors compared to survivors. Serial measurements at 0, 12, 24, 48, 72, and 96 h showed that IL-6 showed better kinetics in the survivor group and was decreased in more than 86% of survivors by the second day.PCT can support the diagnosis of bacterial infection, especially in septic shock and severe sepsis patients [3].
Dornbusch HJ studied non-infectious causes of elevated procalcitonin and C-reactive protein serum levels in pediatric patients with hematologic and oncologic disorders. In the majority of the non-infectious episodes PCT and CRP increased to serum levels statistically indistinguishable from Gram-negative sepsis. PCT and CRP are of limited value as diagnostic markers of sepsis during T-cell-directed immunomodulatory treatment, granulocyte support, or acute GvHD [4].
The aim of qualitative review by Sakr Y was to evaluate the role of PCT measurements in febrile neutropenic patients in differentiating between various causes of fever and to investigate the value of PCT levels in terms of diagnosing infection or predicting outcome in these patients. PCT seems to be able to discriminate fever due to systemic forms of infection from non-infectious etiologies. Patients with fungal infection may have a delayed increase in PCT levels. PCT has a minimal role, if any, in discriminating Gram-negative from Gram-positive infections. PCT may be useful in outcome prediction in patients with febrile neutropenia but is not superior to interleukin-6 or C-reactive protein concentrations for this purpose [5].
Assessment of procalcitonin as a diagnostic and prognostic marker in patients with solid tumors and febrile neutropenia was done by Jimeno A et al. It was concluded that baseline PCT levels were higher in patients who had febrile neutropenia with bacteremia compared with patients who had clinical infections or fever of unknown origin. PCT helped to identify patients who had microbiologic infections and patients who were at high risk of treatment failure, and PCT may constitute a complementary tool in the initial assessment of such patients [6].
In another study by Svaldi M et al on procalcitonin, there was a reduced sensitivity and specificity in heavily leucopenic and immunosuppressed patients,
procalcitonin (PCT) had proven to be a very sensitive marker of sepsis for non-leucopenic patients. Thus, it was concluded that procalcitonin is an excellent sepsis marker with a high positive and negative-predictive value in patients with WBC count >10x1.09/l, but it does not work satisfactorily below this leucocyte count [7].
Similar study by Al-Nawas B et al, the authors observed a high serum levels of PCT in patients with sepsis or severe infection. Patients with no alteration in their immune system showed high PCT values up to day 5, decreasing to normal levels by day 9. Patients with sepsis and immunodeficiency had high values on days 0 to 2, similar to the first group, but showed significantly lower levels on the following 3 days. PCT concentrations fell to base line levels on days 6 to 9 of the sepsis episode in both groups. The observed difference was not significantly related to the kind of causative microorganism or a culture negative sepsis. Leukopenia seemed to go together with lower PCT values after day 2 of the episode [8].
Procalcitonin concentrations in patients with neutropenic fever was also studied by Ruokonen E et al. The procalcitonin concentration increased rapidly in patients with infection; the response was detectable within 8 h of the onset of fever. Procalcitonin is a specific but not a sensitive marker of infection in patients with neutropenic fever. Its poor sensitivity was related to an absent or delayed response in patients with gram-positive infections. Considerable overlap between infected and noninfected patients was found in levels of endotoxin, tumor necrosis factor, and interleukin-6. Sarmati L et al inferred that procalcitonin is a reliable marker of severe systemic infection in neutropenic hematological patients with mucositis. Procalcitonin (PCT) has become increasingly popular as a novel marker of infection. The use of this marker in hematological patients has provided controversial results and no agreement exists about the capacity of PTC to differentiate fever by other inflammatory processes such as mucositis and Graft versus Host diseases (GVHD) [9,10].
Our patient also had a high procalcitonin level with a negative microbiological and autoimmune workup. Also there was no clinical and biochemical response to antibiotic and antifungal therapy. Once the diagnosis of AML was made, chemotherapy was initiated and the general condition of the patient improved and there was a dramatic fall in procalcitonin level.