Procalcitonin and other inflammatory markers in patients with sepsis and septic shock: A single-center experience

Abstract

Original Article introduCtionSepsis, severe sepsis, and septic shock are the spectra of the deleterious host response to infection. Even with optimal treatment, mortality due to severe sepsis or septic shock is approximately 40% and can exceed 50% in the sickest patients. [1] Patients with systemic infection and organ dysfunction or shock are often difficult to distinguish from patients with similar clinical signs and laboratory finding but without infection.Serum procalcitonin (PCT), normally produced in the C-cells of the thyroid gland, is the precursor of calcitonin. A specific protease cleaves serum PCT to calcitonin, catacalcin, and an N-terminal residue. Normally, PCT is not released into the blood as it is all cleaved, and hence, they are undetectable in healthy individuals and its level increases in severe infections. In these conditions, serum PCT is probably produced by extra-thyroid tissues as high levels of PCT are found even in those patients who have undergone total thyroidectomy. Parenchymal cells (including the kidney, liver, lung, muscles, and adipocytes) provide the main source of circulating PCT in sepsis. [2] PCT is detectable 3-4 h after an inflammatory stimulus and peaks at 14 h and the remaining elevated for 24 h, with a half-life in the serum of 22-35 h. [3] The pathophysiological role of serum PCT during sepsis is not clear. [4,5] PCT has been studied extensively, and its efficacy as a marker of bacterial infection and critical illness has been proved. As positive bacteriological results may be caused by Objective: The objective of the study was to compare the diagnostic value of serum procalcitonin (PCT), C-reactive protein (CRP), lactic acid, and white blood cells (WBC) as markers of sepsis in critically ill patients in the main tertiary hospital in Qatar. Materials and Methods: The PCT levels and other inflammatory markers (CRP, lactic acid, and WBC) were retrospectively reviewed in 137 consecutive adult patients with a suspected diagnosis of sepsis who admitted to the Internal Medicine inpatient service (i.e., Medical Wards and Medical Intensive Care Unit) at Hamad General Hospital, Qatar. The serum PCT was measured by chemiluminescence immunoassay and the results were compared with commonly used inflammatory markers between the patients with and without proven sepsis. Results: A significantly higher PCT level was observed among patients with severe sepsis and septic shock compared to those without sepsis (19.34 ± 50 and 25.91 ± 61.3 vs. 4.72 ± 10, respectively; P = 0.011). No significant differences were found in CRP and WBC between these groups. Nonsurvivors of both septic and nonseptic groups had a mean PCT level of 22.48 ± 8.26 significantly higher than that measured in survivors of both the groups (P = 0.01), a difference not evident in other inflammatory parameters. Conclusions: PCT is a highly efficient inflammatory laboratory parameter for the diagnosis of severe sepsis and septic shock, but WBC and CRP levels were of little value. PCT value assists in the diagnosis of septic ...