Neutrophil and Lymphocyte Counts and the Neutrophil-to-lymphocyte Ratio as a Predictor of Fever Following Percutaneous Nephrolithotomy in Patients Without Risk Factors

Percutaneous nephrolithotomy (PNL) is a minimally invasive treatment commonly used for renal calculi. However, the prevalence of postoperative fever is reported to be 16.7%-35%, even with appropriate prophylactic antibiotic therapy and a sterile urine culture. The most probable causes are urinary extravasation and bacteremia. Although it is important to postoperatively isolate the causative bacteria, bacterial isolation may not always be possible, and urinary and blood cultures may prove negative. In addition, establishing the etiology of fever could be time-consuming and the techniques involved may generate pseudo-negative results owing to several factors, especially the antibiotics used prophylactically. This can result in a prolonged hospital stay and increased the cost of patient care.

The most commonly used parameters for the early diagnosis of bacterial infections, despite their limited use, are C-reactive protein, white blood cell count, and neutrophil count . Superior parameters include procalcitonin, pro-adrenomedullin, interleukin (IL)-6, and IL-8, but their use is limited by their lack of availability in some centers and their higher costs. Recently, the ratio of neutrophil count to lymphocyte count (NLR) has been proposed as an effective, simple, and useful biomarker for the early diagnosis of bacterial infections. However, these tests are used after the emergence of fever. As yet, no single parameter has been proposed for predicting postoperative fever in the absence of preoperative factors known to cause fever.

The aim of this study was to investigate whether neutrophil count, lymphocyte count, and NLR obtained from routine preoperative blood tests could be used in predicting fever following PNL in patients with no risk factors for infection.