ABSTRACT Objective This study aimed to assess vitamin D deficiency in a cohort of healthy young adults using the novel inflammatory parameters neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), monocyte-to-high-density lipoprotein (HDL) cholesterol ratio (MHR), and uric acid-to-HDL cholesterol ratio (UHR). Subjects and methods The study included 1,190 participants, with demographic and laboratory data retrieved retrospectively from our institution’s database. The inclusion criteria were ages 22-35 years; absence of acute, subacute, or chronic diseases; no regular medication use; and laboratory values within specified reference ranges. The exclusion criteria were pregnancy, diagnosis of malignancy, and laboratory measurements indicating infection. Participants were categorized into four groups based on vitamin D levels for comparative analysis of study parameters. Correlation analyses were conducted between these parameters and 25-hydroxyvitamin D levels, followed by receiver-operating characteristic analyses to determine the parameters’ sensitivity and specificity in detecting vitamin D deficiency. Additionally, regression analyses were performed to identify potential risk factors for vitamin D deficiency. Results Subjects in Groups A1 and A2 exhibited higher MHR and UHR than those in Groups A3 and A4 (p < 0.001). Both MHR and UHR correlated negatively with vitamin D levels (r = -0.377 and r = -0.363, respectively; p < 0.001). The area under the curve for MHR was 0.766 (95% confidence interval [CI] 0.739-0.794), with a 79% sensitivity and 61% specificity for identification of vitamin D deficiency. Increased MHR and UHR were independent risk factors for vitamin D deficiency (β = 0.219, odds ratio 1.244 95% CI 1.178-1.315, and β = 2.202, odds ratio 1.224, 95% CI 1.150-1.303). Conclusions Both MHR and UHR can be useful in predicting vitamin D deficiency in healthy young adults and may serve as valuable screening tools. neutrophiltolymphocyte neutrophil lymphocyte NLR, NLR , (NLR) platelettolymphocyte platelet PLR, PLR (PLR) monocytetolymphocyte monocyte MLR, MLR (MLR) monocytetohighdensity high density HDL (HDL MHR, (MHR) acidtoHDL acid UHR. . (UHR) 1190 1 190 1,19 participants institutions institution s database 2235 22 35 22-3 years acute subacute diseases use ranges pregnancy malignancy infection 25hydroxyvitamin hydroxyvitamin 25 receiveroperating receiver operating Additionally A 0.001. 0001 0.001 0 001 0.001) 0.377 0377 377 -0.37 0.363, 0363 363 -0.363 respectively 0766 766 0.76 95 (95 [CI 0.7390.794, 07390794 0.739 0.794 739 794 0.739-0.794) 79 61 0219 219 0.219 1244 244 1.24 1.1781.315, 11781315 1.178 1.315, 178 315 1.178-1.315 2202 2 202 2.202 1224 224 1.224 1.1501.303. 11501303 1.150 1.303 150 303 1.150-1.303) tools (NLR (PLR (MLR (MHR (UHR 119 19 1,1 223 3 22- 000 0.00 00 0.37 037 37 -0.3 0.363 036 36 -0.36 076 76 0.7 9 (9 7390 0.7390.794 0739079 0739 0.73 0794 0.79 73 0.739-0.794 7 6 021 21 0.21 124 24 1.2 1781 1.1781.315 1178131 1178 1.17 1315 1.315 17 31 1.178-1.31 220 20 2.20 122 1.22 1501 1.1501.303 1150130 1150 1.15 1303 1.30 15 30 1.150-1.303 11 1, 0.0 0.3 03 -0. 0.36 07 0. ( 0.7390.79 073907 073 079 0.739-0.79 02 0.2 12 1. 1.1781.31 117813 117 1.1 131 1.31 1.178-1.3 2.2 1.1501.30 115013 115 130 1.3 1.150-1.30 -0 0.7390.7 07390 0.739-0.7 1.1781.3 11781 13 1.178-1. 2. 1.1501.3 11501 1.150-1.3 - 0.7390. 0.739-0. 1.1781. 1.178-1 1.1501. 1.150-1. 0.7390 0.739-0 1.1781 1.178- 1.1501 1.150-1 0.739- 1.150-