Circulating Omentin-1 Levels in Iron-Deficiency Anaemia and β-Thalassemia Trait: Associations with Iron and Metabolic Parameters

Background/Objectives: Omentin-1 (intelectin-1) is an adipocytokine with anti-inflammatory, insulin-sensitizing, and iron-regulatory properties. This study aimed to compare circulating omentin-1 levels in patients with (IDA) and β-thalassemia trait and to evaluate their associations with haematological, iron-related, and metabolic parameters. Methods: A total of 90 adults (n = 90), including 29 patients with IDA, 31 individuals with β-thalassemia trait, and 30 healthy controls. Haematological indices, iron parameters, biochemical markers, and plasma omentin-1 levels were measured. Group comparisons, correlation analyses, multivariable linear regression, and receiver operating characteristic (ROC) curve analyses were performed. Results: Plasma omentin-1 concentrations were significantly lower in patients with hypochromic microcytic anaemia than in healthy controls (36.4 vs. 147.7 ng/mL, p < 0.001). Among subgroups, the lowest levels were observed in IDA patients, followed by β-thalassemia trait and controls (p < 0.001). Omentin-1 showed positive correlations with haemoglobin, MCV, MCH, ferritin, serum iron, total cholesterol, HDL-C, and LDL-C, whereas negative correlations were observed with age, HbA1c, glucose, RDW, and total iron-binding capacity (all p < 0.05). In multivariable analysis, age (β = −0.215, p = 0.046), female sex (β = 0.305, p = 0.028), and MCV (β = 0.334, p = 0.015) were independent predictors of omentin-1 levels. ROC analysis demonstrated excellent discrimination between IDA and controls (AUC = 0.93) and good discrimination between β-thalassemia trait and controls (AUC = 0.79). Conclusions: Omentin-1 levels are reduced in IDA and β-thalassemia trait and are closely associated with iron status, erythroid indices, and metabolic parameters. Omentin-1 may serve as an adjunct biomarker for hypochromic microcytic anaemia, particularly in distinguishing affected individuals from healthy subjects. However, its limited utility in distinguishing iron-deficiency anaemia from β-thalassemia trait indicates that it should be used alongside established haematological and iron-related parameters.