Best Practices & Benign Disease
Introduction & Objective : Patients presenting with obstructive urolithiasis warrant emergent urinary drainage if there is clinical suspicion of concurrent urinary infection. Procalcitonin (PCT) is an ultrasensitive serum marker of systemic infection and sepsis. Our objective was to evaluate the utility of PCT as an early marker for the diagnosis and differentiation of urinary tract infection and sepsis in patients presenting with obstructive urolithiasis.
Methods : With IRB approval, we generated a prospective database of patients presenting to Hershey Medical Center with obstructive urolithiasis. All patients had PCT drawn at time of presentation along with standard of care workup. Clinical course, including urine and blood cultures, was followed and correlated with admission PCT and WBC values. Comparison between values was made with the Mann-Whitney test. Receiver operating characteristic (ROC) curves were constructed to assess the predictive ability of PCT and WBC for infection and sepsis.
Results : Of the 30 patients accrued, 7 and 3 patients were found to have positive urine and blood cultures, respectively and 7 patients met criteria for sepsis. Elevated PCT was highly prognostic of positive cultures (p=0.00056) and sepsis (p=0.00028). PCT was more sensitive than WBC in predicting positive cultures with an area under the ROC curve of 0.922 (urine) and 0.981 (blood) for PCT compared to 0.643 (urine) and 0.432 (blood) for WBC. Youden’s indices for PCT were determined to be 0.14 ng/mL and 1.0 ng/mL for diagnosis of positive urine and blood cultures, respectively. PCT >0.14 ng/ml was sensitive (0.86) and specific (0.83) for positive urine culture, while a PCT of>1.0 ng/mL was highly sensitive (1) and specific (0.96) for positive blood cultures.
Conclusions : PCT is an effective biomarker in the setting of obstructive urolithiasis, and outperformed WBC as an early predictor of urinary tract infection, including bacteremia and sepsis. Further studies may prove PCT to be a valuable tool in the urologist’s armamentarium in the workup of acute obstructive urolithiasis.