Characterization by image analysis of the dose vs response curve for a qualitative serum hCG lateral flow immunoassay

•Investigated test-line response curve for a qualitative serum hCG lateral flow assay.•Image analysis was performed to obtain the Test line integral (S) vs [hCG].•S vs [hCG] was well-characterized by a hyperbola: S/Smax = [hCG]/([hCG] + K).•K was 202 mIU/mL; interval between 10% and 90% Smax was a factor of 81 in [hCG].•At claimed sensitivity of [hCG] = 10 mIU/mL, S/N was 2.7.