Signosis' steroid hormone ELISA kits utilize a competitive ELISA assay to quantify steroid hormone levels in samples. First, the plate is coated with the target hormone conjugated to a protein, which competes with the free hormones in the samples that are added to the plate. After the samples containing free hormone are added to the plate, an anti-hormone antibody labeled with biotin is added to the samples and binds to both the free hormones and conjugated hormones immobilized on the plate. The plate is then washed to remove any sample and antibodies not binding to the hormones bound on the plate. The antibodies that are bound to the immobilized hormones on the plate are measured by adding Streptavidin-HRP, which binds to the biotin-labeled antibodies. To detect the HRP, TMB substrate is added, which produces a blue color when it interacts with HRP. After the blue color fully develops, the reaction is terminated with an acidic Stop solution, which changes the blue color to yellow. The intensity of the yellow color is measured at an absorbance of 450 nm and is used to determine the hormone level in the sample. Because this is a competitive ELISA assay, the signal is inversely proportional to the hormone concentration, since higher free hormone concentrations will prevent the labeled antibody from binding to the plate.

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The assay can be used to analyze serum, cell, tissue, and other liquid samples from human, mouse, and rat models.

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The Steroid Hormone ELISA Combo Kit includes four hormones on a single 96-well plate (24 wells per hormone) and enables simultaneous and quantitative detection of multiple targets in a single assay.

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Limit of Detection

• Cortisol: 2–50 pg/mL
• Testosterone: 5–100 pg/mL
• Estradiol (E2): 8–20 pg/mL
• Progesterone: 5–50 pg/mL