Thyroxine (T4), the primary hormone produced by the thyroid gland, plays a vital role in regulating metabolism, growth, and development. This hormone is synthesized from tyrosine residues in thyroglobulin and contains four iodine atoms, making it a key component of iodine metabolism in the body. T4 exerts its effects by being converted into the more active triiodothyronine (T3), which influences numerous cellular processes by binding to thyroid hormone receptors.

Research has highlighted the critical involvement of thyroxine in the pathogenesis of various diseases, including hypothyroidism, hyperthyroidism, cardiovascular disorders, and metabolic syndromes. Dysregulation of T4 levels affects energy homeostasis, thermogenesis, and tissue differentiation, with far-reaching impacts on nearly every organ system. Moreover, thyroid hormone imbalances have been linked to alterations in other endocrine pathways, emphasizing the interconnected nature of T4 in maintaining physiological and metabolic equilibrium.

The RayBio^® T4 ELISA Kit is a competitive enzyme immunoassay developed for rapid detection and quantitation of T4 in serum, plasma, cell supernatant or urine samples collected from humans. The quantity of T4 is determined by a known T4 standard curve. This kit has a high sensitivity of approximately 0.494 ng/mL. Each kit provides sufficient reagents to perform up to 96 assays, including standard curve and unknown samples.

• Strip plates and additional reagents allow for use in multiple experiments
• Quantitative protein detection
• Establishes normal range
• The best products for confirmation of antibody array data

• Microplate reader capable of measuring absorbance at 450 nm
• Precision pipettes to deliver 2 μL to 1 mL volumes
• Adjustable 1-25 mL pipettes for reagent preparation
• 100 mL and 1-liter graduated cylinders
• Absorbent paper
• Distilled or deionized water
• GraphPad Prism or SigmaPlot software (or other software which can perform four-parameter logistic regression models)
• Tubes to prepare standard or sample dilutions
• Orbital shaker
• Aluminum foil
• Plastic wrap

1. Prepare all reagents, samples and standards as instructed.
2. Add 50 μL standards or samples to appropriate well. Incubate for 10 minutes at room temperature.
3. Add 50 μL anti-T4 to appropriate well. Incubate 1 hour at room temperature. And wash 5 times.
4. Add 100 μL prepared HRP-Secondary antibody solution. Incubate 1 hour at room temperature. And wash 5 times.
5. Add 100 μL TMB One-Step Substrate Reagent to each well. Incubate 2-10 minutes at room temperature.
6. Add 50 μL Stop Solution to each well. Read at 450 nm immediately.

The entire kit may be stored at -20°C to -80°C for up to 1 year from the date of shipment. For extended storage, it is recommended to store it at -80°C. Avoid repeated freeze-thaw cycles.