Can serum procalcitonin levels be useful in predicting spontaneous ureteral stone passage?

Medical expulsive therapy (MET) is recommended for ureteral stones when there is no indication for interventional treatment. Spontaneous passage (SP) may not always be perceived in patients undergoing MET. We aimed to demonstrate the effects of inflammatory factors on spontaneous ureteral stone passage in patients undergoing MET.

Our study was conducted between August and November, 2016, in healthy volunteers and patients with a single distal ureteral stone between 5 and 10 mm in diameter and no indications for interventional therapy. Blood and urine samples from all patients and healthy volunteers were tested. The patients were followed up every 2 weeks for 1 month unless emergency situations appeared. Patients with stone-free status at follow-up were concluded to have achieved complete stone passage [SP(+)], and failure [SP(-)] was concluded if the patient had not passed the stone by the end of the study. Blood samples of the patients and the control group were analyzed, recording WBC (white blood cell), CRP (c-reactive protein), SED (sedimentation), MPV (mean platelet volume), NLR (neutrophil-to-lymphocyte ratio), and serum procalcitonin levels. Abnormalities in urine samples were recorded. All patients received diclofenac sodium 75 mg/day, tamsulosin 0.4 mg/day, and at least 3 l/day fluid intake. Patients were followed for a month with kidney, ureter, bladder (KUB) plain films, ultrasonography (USG), and unenhanced abdominal CT scans while undergoing MET. Comparative statistical analyses were performed between the SP(+) and SP(-) groups.

The procalcitonin levels of the SP(-) group were significantly higher (207 ± 145.1 pg/ml) than in the SP(+) group (132.7 ± 28.1 pg/ml) (p = 0.000). The leucocyturia rate of the SP(-) group was significantly higher than in the SP(+) group (p = 0.004). Based on the ROC curve analysis, 160 pg/ml (86.7% sensitivity, 70.8% specificity, p < 0.001; AUC: 0.788 95% CI (0.658-0.917) was identified as the optimal cut-off value for procalcitonin. In logistic regression analysis, a significant efficacy of procalcitonin and leucocyturia was observed in the univariate analysis on spontaneous passage. In the multivariate analysis, significant independent activity was observed with procalcitonin. (p < 0.05).

Our findings suggest that high procalcitonin levels and the presence of leucocyturia have a strong negative effect on SP of ureteral stones between 5 and 10 mm in diameter. This relationship can be explained by stone impaction, possibly caused by increased mucosal inflammation.