Validation of an Enzyme‐Linked Immunosorbent Assay for Measuring Leptin, a Key Metabolic Hormone, in Dried Blood Spot Samples

Objectives Leptin is an established biomarker of appetite regulation and energy status. Problematically, heavy reliance on invasive venipuncture sampling has limited leptin research with diverse human populations and groups such as children. Key questions remain about leptin's evolution and biological roles across the full range of humans. Here, we present and validate a new minimally invasive approach for measuring leptin in finger‐prick dried blood spots (DBS) using a commercial ELISA kit. Methods The Human Leptin Quantikine QuicKit ELISA (R&D Systems, QK398) was validated using matched serum and DBS samples from 40 adults. Passing–Bablok regression assessed the relationship between leptin DBS and leptin serum . Dilutional linearity, reliability, spike‐and‐recovery, limit of detection, and stability tests evaluated assay performance and potential DBS matrix interference. Results Leptin was reliably measured in all DBS samples (average = 312 pg/mL), with DBS intra‐ and inter‐assay CVs of 3.3% and 2.0%, respectively. Matched leptin DBS and leptin serum measurements showed excellent agreement (Pearson's R = 0.97), with no apparent bias (Bland‐Altman bias = 4.7). Leptin measurement in DBS was stable for at least 72 h at 26.2°C and 37°C and showed no degradation across eight freeze–thaw cycles ( p > 0.05). Conclusions Leptin can be reliably and stably measured in minimally invasive DBS samples, expanding research on energetics and appetite regulation across a wider range of human groups and settings.