Background Acute gout arthritis is usually accompanied by tenderness, swelling, redness and fever. These features and laboratory findings including leukocytosis, elevation of serum ESR or CRP levels, are similar to those of infectious diseases. Moreover, normal to low serum uric acid levels have been noted in many cases of acute gout arthritis. For these reasons, the differential diagnosis of acute gout arthritis with infectious disease can be difficult.
Objectives Procalcitonin, the precursor peptide of calcitonin, is known to be elevated in the patients with bacterial infection. We investigate whether or not serum procalcitonin levels are higher in patients with acute gout arthritis than in the others. We also evaluate the usefulness of procalcitonin for differentiating diagnosis between acute gout arthritis and bacterial infection.
Methods The serum samples were obtained from 67 patients with acute gout arthritis and 90 age-matched patients with bacterial infection. Serum procalcitonin levels were measured by an enzyme-linked fluorescent assay.
Results The serum procalcitonin levels in patients with acute gouty arthritis were significantly lower than those in patients with bacterial infection (0.096±0.105 ng/mL vs 4.941±13.763 ng/mL, p =0.001). However, other inflammatory parameters, such as ESR, CRP and WBC, showed no significant differences between these two groups. Patients with acute gout arthritis had statistically higher serum uric acid levels than the patients with bacterial infection (7.62±2.03 mg/dL vs 5.19±2.36 mg/dL, p<0.001); however, 19.4% (13/67) among the acute gout arthritis group had lower uric acid level (below 6.0 mg/dL). To determine the discriminative ability of procalcitonin between acute gout arthritis and bacterial infection, we conducted ROC analysis about procalcitonin, uric acid, ESR, CRP and WBC. The area under the curve (AUC) of procalcitonin and uric acid were 0.852 (95% CI 0.793-0.911, p<0.001) and 0.808 (95% CI 0.738-878, p<0.001), respectively. There was no significance at ESR, CRP and WBC. With a cut off value of 0.095 ng/dL, the sum of sensitivity and specificity of procalcitonin were the highest (80.0% and 80.6%, respectively).
Conclusions Serum procalcitonin levels were significantly lower in patient with acute gout arthritis than in patients with bacterial infection. The serum procalcitonin level is expected to be a useful serologic marker for the differentiating acute gout arthritis from bacterial infection.
Simon L et al. Serum procalcitonin and C-reactive protein levels as markers of bacterial infection: a systematic review and meta-analysis. Clin Infect Dis 2004:39:206-17.
Disclosure of Interest None declared