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| Sample Type(s) | Serum, Plasma, Other biological fluids |
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Features & Benefits
EliKine™ fT4 ELISA Kit has high sensitivity and excellent specificity for detection of fT4. No significant cross-reactivity or interference between fT4 and analogues was observed.
Background
Over 99% of Triiodothyronine (T4) circulates in blood is bound to carrier proteins; thyroxine-binding globulin (TBG). However, only the free (unbound) portion of T4 is responsible for the biological action. Further, the concentrations of the carrier proteins are altered in many clinical conditions, such as pregnancy. In normal thyroid function as the concentrations of the carrier proteins alters, the total T4 level changes so that the free T4 concentration remains constant. Thus, measurements of free T4 concentrations correlate more reliably with clinical status than total T4 levels. The increase in total T4 levels associated with pregnancy, oral contraceptives and estrogen therapy result in higher total T4 levels while the free T4 concentration remains basically unchanged.
This Free Thyroxine (fT4) ELISA kit is validated for use with Serum, Plasma, Other biological fluids. Samples should be collected, processed, and stored correctly to preserve analyte integrity — avoid repeated freeze-thaw cycles and centrifuge to remove particulates before use. Dilute samples exceeding the kit's detection range using the supplied assay diluent. Hemolytic, icteric, or lipemic samples may affect assay performance and should be tested with caution.
This is a competitive ELISA kit employing an HRP (horseradish peroxidase)-conjugated secondary antibody paired with a TMB (3,3′,5,5′-tetramethylbenzidine) colorimetric substrate. In the competitive format, the target analyte Free Thyroxine (fT4) captured on the microplate surface is detected by the conjugated antibody, generating a colorimetric signal proportional to analyte concentration. The reaction is stopped and absorbance measured at 450 nm on a standard microplate reader.
The complete protocol, from sample addition to final plate reading, requires approximately 3–5 hours. This includes two incubation periods (analyte binding and detection antibody steps), intermediate wash cycles to remove unbound material, 15–30 minutes of TMB substrate development, and final stop-solution addition before absorbance reading. Exact timing will vary with experience level and the number of samples processed in parallel.
Required equipment: (1) a microplate spectrophotometer capable of reading absorbance at 450 nm (reference wavelength 540–570 nm recommended for background correction); (2) precision single-channel or multichannel pipettes; (3) a plate washer or multichannel aspirator; (4) a microcentrifuge for sample clarification; and (5) a 37°C incubator or stable room-temperature environment. No fluorescence or luminescence reader is required — standard colorimetric plate readers are fully compatible with this kit.
This ELISA kit is formally validated for Human. Cross-reactivity with species not listed in the specification has not been independently characterized. Variability in protein sequence homology across species means that performance in unlisted species cannot be guaranteed without additional validation. For cross-species detection requirements or non-standard sample matrices, please contact BioHippo support or refer to the manufacturer's technical team for guidance.
Can't Find What You're Looking For? We can help you source the best match or customize an ELISA solution for your study. Options may include alternative target synonyms, different species reactivity, sample type/matrix compatibility (serum/plasma/lysate/supernatant), assay format (sandwich/competitive), sensitivity/range, detection chemistry (colorimetric/fluorescent/chemiluminescent), plate format (pre-coated/uncoated, strips vs full plate), and bulk or custom packaging. Click Talk to a Scientist to submit a request form, email us at support@biohippo.com, or explore our Research Services for additional support. Our team will be in contact with you shortly.
