Diagnostic value of neutrophil-to-lymphocyte, platelet-to-lymphocyte, and lymphocyte-to-monocyte ratios for assessing organ and multiorgan involvement in sarcoidosis: a retrospective single-center study

Background: Sarcoidosis is a heterogeneous disease lacking reliable biomarkers for organ involvement. Indices derived from the complete blood count (CBC), including the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR), have emerged as accessible markers of systemic inflammation. Objectives: To assess whether CBC parameters and NLR, PLR, and LMR vary across demographic and clinical features in sarcoidosis, and to evaluate their diagnostic performance for organ-specific and multiorgan involvement. Methods: A retrospective, single-center observational study included adults with sarcoidosis diagnosed between 2000 and 2025. Age- and sex-adjusted logistic regression evaluated associations between hematologic indices at diagnosis and organ involvement. Additional logistic regression using analytical parameters evaluated associations between blood count-derived ratios and multiorgan involvement. Firth's correction was applied when the events-per-variable ratio was < 10, and analyses were repeated using log-transformed hematologic ratios when skewness coefficient > 2. Diagnostic performance was assessed by receiver operating characteristic (ROC) curve analysis. Results: A total of 229 patients were included (mean age 51.34 years; 57.64% women). Median values for NLR, PLR, and LMR were 2.57, 158.97, and 3.17, respectively. Higher NLR and PLR were independently associated with extrathoracic lymph node involvement (NLR: OR = 13.42, 95% CI 1.91-94.32, p = 0.001, PLR: OR = 1.01, 95% CI 1.00-1.01, p = 0.008). NLR was associated with splenic involvement (OR = 83.05, 95% CI 6.75-1021.09, p = 0.001); Firth's correction confirmed the association (OR = 23.72; 95% CI 7.53-74.70). Log-transformed NLR remained associated with splenic (OR = 2.74 per 10% increase, 95% CI 1.92-3.91) and extrathoracic lymph node involvement (OR = 2.17 per 10% increase, 95% CI 1.60-2.94). NLR was associated with multiorgan disease (OR = 24.60, 95% CI 5.90-102.00, p < 0.001), and log-transformed NLR showed a consistent association (OR = 2.13 per 10% increase, 95% CI 1.56-2.91). The area under the ROC curve was 0.51 for >= 2 organs, 0.69 for >= 3 organs, and 0.99 for >= 4 organs. Conclusion: NLR was independently associated with multiorgan disease, splenic and extrathoracic lymph node involvement. PLR was independently associated with extrathoracic lymph node involvement.