Association of vitamin D status with novel hemogram-derived inflammatory indices in preterm infants

BACKGROUND: Vitamin D plays an important role in immune regulation and inflammatory responses. Hemogram-derived inflammatory indices such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and aggregate index of systemic inflammation (AISI) have recently emerged as practical markers of systemic inflammation. However, data regarding the relationship between vitamin D status and these inflammatory indices in preterm infants are limited. OBJECTIVE: To evaluate the association between vitamin D levels and hemogram-derived inflammatory indices in preterm infants hospitalized in the neonatal intensive care unit. METHODS: This retrospective study included 212 preterm infants born at or below 34 weeks of gestation. Serum 25-hydroxyvitamin D [25(OH)D] levels obtained during the first postnatal week and complete blood count (CBC) parameters measured on the first day of life were analyzed. Infants were classified as vitamin D deficient (< 12 ng/mL), insufficient (12-20 ng/mL), or sufficient (≥ 20 ng/mL). Hemogram-derived inflammatory indices including NLR, PLR, monocyte-to-lymphocyte ratio (MLR), SII, SIRI, and AISI were calculated and compared between groups. RESULTS: The mean vitamin D level was 15.4 ± 10.3 ng/mL. Vitamin D deficiency, insufficiency, and sufficiency were detected in 44.3%, 27.8%, and 27.8% of infants, respectively. No significant differences were observed among vitamin D groups regarding WBC (White Blood Cell), C-reactive protein (CRP), NLR, PLR, MLR, SII, SIRI, or AISI values (all p > 0.05). Similarly, no significant correlations were found between vitamin D levels and inflammatory indices. Infants born before 32 weeks' gestation had significantly higher NLR, SII, SIRI, and AISI values compared with infants ≥ 32 weeks (all p < 0.01). CONCLUSION: Vitamin D status was not associated with hemogram-derived inflammatory indices in preterm infants, even after adjustment for relevant perinatal confounders. Further prospective studies are needed to clarify the relationship between vitamin D status and inflammatory profiles in this population.