Re: Procalcitonin: a new parameter for the diagnosis of bacterial infection in the perioperative period. Oczenski et al., Eur J Anaesthesiol 1998; 15

Abstract

Sir: Major advances in our understanding of sepsis have made it clear that uncontrolled infections are not the only cause of systemic inflammation and that other stimuli, such as pancreatitis, major trauma and thermal injury, can also trigger a systemic inflammatory response and lead to organ failure. Common signs of systemic inflammation such as changes in body temperature, leucocytosis and tachycardia may therefore have an infectious or non-infectious aetiology. Bacteriological evidence of infection, although considered a gold standard, may surprisingly not always be helpful in differentiating between infectious and non-infectious inflammation. Negative blood cultures do not exclude an infection, and multiple samples may be required over extended periods before positive cultures emerge. Because these common clinical and laboratory parameters lack sensitivity and specificity, an early marker of the infectious aetiology of a generalized inflammatory response is needed which would allow early (differential) diagnosis and initiation of specific therapeutic interventions. Furthermore, the disappointing results of immunomodulatory trials in septic patients has raised doubts as to whether conventional clinical and laboratory criteria used for recruiting septic patients may suffice in identifying groups of patients who would most likely benefit from such therapies [1]. New indicators are thus also needed to define the inflammatory response better and help target the populations of septic patients who would benefit from such trials. In recent years, a variety of laboratory and immunological parameters have been proposed as possible indicators of severe inflammatory response to infections. One such parameter, procalcitonin, has emerged as a possible marker of severe generalized infection [2]. Oczenski and co-workers reviewed the current literature concerning procalcitonin [3]. They concluded that procalcitonin is a good indicator of the activity and severity of the inflammatory response and may be used for monitoring severe bacterial infections. However, as we have pointed out elsewhere [2], although procalcitonin offers considerable advantages in comparison with conventionally used laboratory parameters, it does not fulfil all the criteria of an ideal marker for severe microbial infections. Procalcitonin may not or may only slightly increase when infection remains confined to a tissue or organ with no systemic manifestations. For the same reason, although elevated procalcitonin levels during severe infections may decrease to very low levels with appropriate therapy, this does not always indicate complete eradication of the infection, but merely that generalization of the infection is under control. Continuation of antibiotic therapy or surgical measures may be necessary until all clinical signs of infection have disappeared. Furthermore, procalcitonin levels may also be elevated during non-infectious inflammatory states such as after major trauma or surgery and after cardiopulmonary bypass. In addition, patients with C-cell carcinoma of the thyroid gland and small-cell carcinoma of the lung without underlying infection may also have increases in procalcitonin levels [4]. Many other important questions pertaining to procalcitonin remain unanswered. Is procalcitonin release related to bacterial products (alone) or do cytokines also have a role? Which cells produce procalcitonin during severe infections? What specific endocrinological or immunological function does procalcitonin serve during severe infection? Because of these open questions and limitations, more clinical and laboratory studies are needed to uncover the nature and utility of this parameter in inflammatory states. K. REINHART W. KARZAI Department of Anesthesiology and Intensive Care Medicine, University Hospital, Friedrich-Schiller-University Jena, 07740 Jena, Germany