KTE0004 | EliKine™ Free Triiodothyronine (fT3) ELISA Kit — Capturing the Biologically Active Fraction of Thyroid Hormone

fT3: The Active Face of Thyroid Hormone

Triiodothyronine (T3) is the most biologically active thyroid hormone—possessing approximately three to five times the metabolic activity of T4. But here is the critical detail: the vast majority of T3 in circulation is bound to carrier proteins. Only the free, unbound fraction (free T3, or fT3) can enter target cells and exert biological effects. Measuring total T3 tells you what is present. Measuring fT3 tells you what is actually working. The EliKine™ Free Triiodothyronine (fT3) ELISA Kit (KTE0004) delivers precisely that—accurate quantification of the biologically active fraction.

Competitive ELISA: Designed for Free Hormone Detection

KTE0004 employs the competitive inhibition enzyme immunoassay technique. The microtiter plate is pre-coated with an antibody specific to fT3. Standards or samples compete with biotin-conjugated fT3 for binding to the immobilized antibody. The more fT3 in your sample, the less biotin-conjugated fT3 binds. After washing, avidin-HRP is added, substrate is introduced, and color develops inversely proportional to fT3 concentration. This competitive format is specifically optimized for free hormone detection in the presence of abundant carrier proteins.

Why Free Hormone Measurement Matters

In conditions where carrier protein concentrations are altered—pregnancy, liver disease, nephrotic syndrome, estrogen therapy—total T3 levels can shift without any change in actual thyroid status. Only free T3 provides an accurate reflection of thyroid function in these contexts. KTE0004 ensures you are measuring the biologically relevant fraction, not the protein-bound reservoir.

Broad Species Reactivity

Validated across Bovine, Chicken, Dog, Goat, Human, Monkey, Mouse, Rabbit, Rat, Sheep, and Swine[reference:17], KTE0004 supports multi-species translational research from bench to bedside.

Specifications

• Assay Type: Competitive ELISA (quantitative)[reference:18]
• Sample Types: Serum, Plasma, Other biological fluids[reference:19]
• Assay Duration: 3–4 hours[reference:20]
• Storage: 2–8°C unopened[reference:21]
• Shipping: Gel pack with blue ice[reference:22]

High Sensitivity and Excellent Specificity

The EliKine™ fT3 ELISA Kit has been rigorously validated for high sensitivity and excellent specificity[reference:23]. No significant cross-reactivity or interference between fT3 and analogues was observed[reference:24].

Who Needs This Kit?

• Endocrinologists studying thyroid function and dysfunction
• Toxicologists evaluating thyroid-disrupting chemicals
• Pharmacologists developing thyroid hormone analogs
• Metabolic researchers investigating thermogenesis and energy homeostasis
• Developmental biologists studying thyroid hormone’s role in growth and maturation

🔗 Reference Link: https://www.abbkine.com/product/elikine-free-triiodothyronine-ft3-elisa-kit-kte0004/