Background It has been established that 5% of gouty arthritis could be also infected.(1,2)It is difficult to rule out infectious arthritis from a gouty arthritis when the latter has been demonstrated by the existence of crystals. Both entities show elevated acute phase reactants, leukocytosis in peripheral blood and synovial fluid(SF) white cell recount over than 50000 cells. By other hand, peripheral blood level of procalcitonine (PCT) has been shown as a good marker for serious infections useful in an urgency enviroment.(3)
Objectives To determine the usefulness of measurement of procalcitonin (PCT) to discrimine infectious and gouty arthritis in an urgency enviroment.
Methods It is a prospective study that has lasted for a period of six months. We performed a measurement of serum levels of PCT in 39 consecutive patients who presented into the emergency department of our hospital due to knee arthritis and also had a previous diagnosis of gout (no less than five years ago). All patients underwent knee arthrocentesis, microcrystals study, Gram stain, BMI enriched culture medium, SF leukocyte count, and a determination of CRP and ESR in peripheral blood as well as blood white cell count.
Results The study population had an average age of 49 SD 6.9 years and 29/39 were male. Average time from onset of symptoms was 4 SD 0.7 days. Final clinical diagnoses (well documented and confirmed by bacteriology results and/or by the finding of intracellular crystals) were: 9 infectious arthritis, 28 gouty arthritis and 2 who had both of them simultaneously. Age, sex, time from onset of symptoms and CRP, ESR and white cell recount in peripheral blood did not differ significantly between the three groups. The SF white cell recount was similar among three groups. PCT average determination for the three groups was: 2.01 SD 0.4, 0.63 SD 0.2 and 2.51 SD 0.9 (infectious arthritis, gouty arthritis and both simultaneous, respectively ). The difference between PCT measure in the first two groups was statistically significant (p <0.01). It was determined by an ROC curve that a determination of PCT higher or equal than 1.475 established the diagnosis of infectious arthritis with a sensitivity of 100% and a specificity of 88.89% (Likelihood ratio 9.00).
Conclusions Blood peripheral PCT determination may be considered as a useful test to during acute monoarthritis approach in a patient with gout in order to rule out an infectious arthritis. The high sensitivity and specificity for the diagnosis of joint infections demonstrated in this paper, can propose the use of serum concentrations of PCT as a routine test in such situations, but our results should undergo further investigations with larger series, mainly in cases of coexistence of these two types of monoarthritis.
Abrazhda D, Andras L, Van Linthoudt D. Concomitant septic and gouty olecranon bursitis. Praxis (Bern 1994).2007;96(39):1479-82.
Guillén Astete C. Coexistencia de artritis microcristalina y artritis séptica: Una consideración importante a tener en cuenta en la valoración de la monoartritis en urgencias. Emergencias 2012;24(4):337-40
Hügle T, Schuetz P, Mueller B, Laifer G, Tyndall A, Regenass S, et al. Serum procalcitonin for discrimination between septic and non-septic arthritis. Clin. Exp. Rheumatol. 2008;26(3):453-6.
Disclosure of Interest None Declared
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