Dehydroepiandrosterone (DHEA) and Dehydroepiandrosterone Sulfate (DHEA-S) in Broiler Plasma: Analytical Validation of Immunoassays and Comparative Overview Across Avian Species

This study validated immunoassays for measuring circulating DHEA and DHEA-S in broiler plasma and compared the two biomarkers. A commercially available RIA kit for DHEA and a species-independent ELISA kit for DHEA-S were tested against each other and available literature data. Blood samples were collected from 68 female broilers at slaughter. Most sample concentrations were close to the lower calibration range. DHEA concentrations ranged from 52 to 354 pg/mL, whereas DHEA-S values ranged from 76 to 7320 pg/mL. Both assays showed satisfactory validation results, including good precision (intra- and inter-assay CV ≤ 15%), accuracy (recovery ≥ 99%), linearity (R2 > 0.9; run test p > 0.1), and parallelism between calibrator curves and sample dilutions (ANCOVA p > 0.1). However, the DHEA-S assay showed high cross-reactivity with DHEA (160%), making quantitative DHEA-S determination unreliable; therefore, values should be interpreted as an estimate of combined DHEA/DHEA-S concentrations. Consequently, the higher concentrations measured with the DHEA-S ELISA compared with the DHEA RIA (Bland–Altman bias: −525.8 pg/mL) do not indicate a true predominance of DHEA-S. Nevertheless, both assays may represent useful tools for comparative evaluations among samples, although they do not provide reliable information on the physiological interconversion between the two steroids.