This observational study compares the effects of spinal versus general anesthesia on the perioperative systemic inflammatory response in adults undergoing PCNL. Routine clinical laboratory values (NLR, RDW, LAR) obtained preoperatively and postoperatively will be recorded to evaluate between-group and within-group changes. No additional blood sampling will be performed beyond standard care.

The study will be conducted at the Department of Anesthesiology and Reanimation, Elazığ Fethi Sekin City Hospital, among adult patients scheduled for PCNL (ASA I-III). The anesthesia type (spinal vs general) is determined by clinical requirements; investigators do not influence this choice.

Sampling windows:

Preoperative: within ≤6 hours before surgery

Postoperative: first sample obtained within 6-24 hours after surgery Parameters: NLR (neutrophil/lymphocyte), RDW, LAR; plus age, sex, ASA class, operative time, and in-hospital complications.

Statistics: Normality testing; between-group comparisons by independent t-test or Mann-Whitney U; within-group by paired t-test or Wilcoxon; categorical by chi-square; p<0.05 significant. Power considerations target ≥45 per group (total ≥90). No extra biospecimens will be collected beyond routine care.

Inclusion Criteria:

Age ≥18 years

ASA physical status I-III

Scheduled for percutaneous nephrolithotomy (PCNL)

Provided informed consent

Exclusion Criteria:

Active infection or sepsis

Known malignancy

Chronic inflammatory or autoimmune disease (e.g., rheumatoid arthritis, systemic lupus erythematosus)

Current immunosuppressive therapy

Pregnancy

Adult patients (≥18 years, ASA I-III) scheduled for percutaneous nephrolithotomy (PCNL) at a single tertiary care center. Eligible patients will be assigned to spinal or general anesthesia groups based on routine clinical decision-making. Routine perioperative laboratory values (NLR, RDW, LAR) will be collected preoperatively and postoperatively.

Individual participant data (IPD) will not be shared because the study uses routine clinical laboratory results and institutional restrictions do not allow sharing of raw patient-level data. Only de-identified aggregate results will be published in peer-reviewed journals upon request.