AB0168 PROCALCITONIN TEST IN RHEUMATOLOGY
Authors: G. Koilubaeva, G. Tarasova, A. Bolotbekova
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Procalcitonin (PCT) is a biomarker that is typically elevated in severe bacterial infections. The study of the role of PCT in rheumatological patients deserves great attention, both in the diagnosis of concomitant infections and in the differential diagnosis between rheumatic disease activity and infection. <h3>Objectives:</h3> To evaluate the significance of PCT as a specific marker of infection in rheumatological patients. <h3>Methods:</h3> the study included 100 patients with inflammatory rheumatic diseases (systemic lupus erythematosus, rheumatoid arthritis, polymyositis, etc.). A PCT concentration of 0.5 ng/ml was taken as the upper limit of normal. <h3>Results:</h3> Generalized infection was diagnosed in 11 (11%) patients: 1 had generalized tuberculosis, 1 had infective endocarditis, 9 had sepsis. In 9 (82%) of 11, PCT numbers ranged from 2.26 to 19.2 ng/ml. In 2 (18%) low PCT values were determined that were not correlated with the severity of the disease: 0.15 ng/ml - in a patient with sepsis and purulent arthritis, 0.49 ng/ml - in a patient with infective endocarditis, and the diagnoses were verified in both cases. Local infection was detected in 30 (30%) patients, with severe infection diagnosed in 19, and mild local infection in 11. An increase in PCT &gt; 0.5 ng/ml was present in 9 (30%) of 30 patients and was observed only in severe local infection: in 2 (7%) cases, PCT values were very high and amounted to 14.3 and 22.6 ng/ ml (polysegmental pneumonia and focal necrosis and gangrene of the fingers in systemic scleroderma, respectively); in 7 (23%) patients, PCT numbers were relatively low and ranged from 0.61 to 1.95 ng/ml (pneumonia - 4, fungal stomatitis - 1, pseudomembranous colitis - 1, phlegmon of the thigh - 1). There were no signs of infection in 59 patients. In 50 (85%) of them, PCT did not exceed 0.5 ng/ml. A moderate increase in PCT from 0.53 to 1.19 ng/ml was observed in 7 patients (systemic juvenile idiopathic arthritis (sJIA) - 4, Still's disease in adults - 2, systemic lupus erythematosus - 1). In 2 cases, a significant increase in PCT was detected: 4.2 ng/ml - in a patient with rheumatoid arthritis and post-infusion reaction to rituximab administration, 2.24 ng/ml - in a patient with sJIA. <h3>Conclusion:</h3> During systemic infections in patients with rheumatic diseases, PCT increases significantly in most patients. With a severe local infection, some patients may experience a moderate (usually up to 2.2 ng/ml) increase in PCT; for a mild focal infection, an increase in PCT is not typical. In rheumatic diseases of high activity, an increase in PCT may be observed, often moderate (up to 2.0-2.2 ng/ml), mainly with sJIA and Still's disease in adults, which can complicate the differential diagnosis with infection. Determining PCT certainly helps in diagnosing infection in rheumatic diseases, however, in differential diagnosis it is necessary to take into account the entire clinical, instrumental and laboratory symptom complex. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>