Serum Lipocalin-2 Levels in Obese Iraqi Women with Hypothyroidism: Associations with Thyroid Function, Lipid Profile, and Diagnostic Implications

Lipocalin-2 (LCN-2) is a glycoprotein that mediates inflammation and innate immunity, among other biological functions. The study aimed to evaluate LCN-2 levels in obese women, with and without hypothyroidism, to investigate the relationship between LCN-2 levels and BMI and thyroid hormones. Also, to explore the relevance of its level as a diagnostic parameter in these patients. The cross-sectional study involved 140 women aged 18-45 years, divided into four groups of 35: a healthy control (C) group, an obese (H1) group, a newly diagnosed hypothyroid (H2) group, and an obese hypothyroid (H3) group. The BMI, fasting blood glucose (FBG), HbA1c, thyroid hormones, lipid profiles, and LCN-2 levels were assessed for all participants. Results indicated a significant increase in BMI (Kg/m2) among H1 and H3 compared to the C and H2 groups. The levels of FBG, HbA1c, TSH, total cholesterol (TC), triglycerides (TG), LDL, VLDL, AIP and Non-HDL were significantly higher (p<0.05) in the H3 group compared to the H1 and C groups, while T3, T4, and HDL levels were significantly lower. The H3 group showed (p<0.05) a higher LCN-2 level (7.38±1.80 ng/ml) compared to other groups C, H1 and H2 (3.51±0.99, 6.03±1.17 and 4.20±0.82, respectively). A significant positive correlation was found between LCN-2 and BMI in all patient groups. Also, a positive correlation between LCN-2 and TSH was noted in H3 and H2 groups, while a negative correlation with T3 and T4 was noted in the H3 group. For diagnostic discrimination, LCN-2 achieved AUC values of 0.943, 0.883, and 0.976 in comparisons of C versus H1, H2, and H3, respectively. Elevated serum LCN-2 levels are associated with BMI in obese Iraqi women with and without hypothyroidism. LCN-2 may represent a potential biomarker for female obesity, particularly in cases of hypothyroidism. However, further validation in larger, longitudinal studies is needed to confirm these results. This study has some limitations because of its cross-sectional design, small sample size, and lack of free T3/T4, which may limit the interpretation of thyroid function dynamics.