Standard Curve
Example of Human FGF-21 standard curve in Assay Diluent DD8. Plotted are the background-subtracted data.
This standard curve is provided for demonstration only.
Human FGF-21 OneStep ELISA Kit
Human FGF-21 OneStep ELISA Kit
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Product Details
Product Details
Product Specification
| Antigen | FGF-21 |
| Immunogen | Recombinant Protein |
| Antibody Type | Recombinant mAb |
| Reactivity | Hu |
| Purification | Protein A |
| Stability & Storage | 12 months from date of receipt / reconstitution, 2 to 8°C as supplied. |
Kit
| Precision | Intra-assay: 2.0%； Inter-assay: 2.8% |
| Sample type | Serum; EDTA Plasma; Cell Culture Supernatant |
| Assay type | Sandwich (quantitative) |
| Sensitivity | 25.09 pg/mL |
| Range | 78.1 pg/mL – 5000 pg/mL |
| Recovery | Serum: 81% EDTA Plasma: 96% Cell Culture Supernatant: 95% |
| Assay time | 60 minutes |
| Species reactivity | Hu; Mk |
Background
Human FGF-21 (fibroblast growth factor 21) is a metabolic hormone predominantly produced by the liver, with significant expression also found in adipose tissue, pancreas, and skeletal muscle. Unlike classical FGFs, it functions endocrinally via the FGFR1/β-Klotho receptor complex, which is essential for its tissue-specific activity. FGF-21 plays a central role in regulating energy homeostasis, promoting glucose uptake, and enhancing lipid oxidation while suppressing hepatic gluconeogenesis. It is highly induced during fasting and calorie restriction, acting as a key adaptive signal to stimulate ketogenesis and maintain metabolic flexibility. Additionally, FGF-21 exerts beneficial effects on insulin sensitivity, weight reduction, and reduction of hepatic steatosis in preclinical and clinical studies. Dysregulation of FGF-21 has been linked to obesity, type 2 diabetes, nonalcoholic fatty liver disease (NAFLD), and other metabolic disorders. Notably, circulating FGF-21 levels are paradoxically elevated in obese and insulin-resistant individuals, suggesting a state of resistance. Consequently, FGF-21 and its analogs are being actively pursued as promising therapeutic candidates for metabolic syndrome and related hepatometabolic diseases.
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ELISA
Spike Recovery
The recovery of Human FGF-21 was evaluated in activated samples spiked with concentrations spanning the entire assay range.
Dilution Linearity
The concentrations of Human FGF-21 were measured and interpolated from the target standard curves and corrected for sample dilution.
The leftmost bar in the graph shows biological samples diluted in Assay Diluent to 12.5% concentration. "undiluted" was defined as 12.5% biological sample. The subsequent bars represent two-fold serial dilutions of this reference. The mean target concentration was determined to be 2123.9 pg/mL in Human FGF-21.
Serum levels in healthy individuals
Duplicate measurements were performed on serum samples obtained from ten individual healthy donors. Data are reported as dilution factor-corrected interpolated. The resultant mean FGF21 concentration was 229.2 pg/mL, with a distribution spanning 59.5 to 836.7 pg/mL across the donor cohort.
Spike-and-dilution Linearity
To evaluate assay linearity, two samples were spiked with high levels of Human FGF-21 in different matrices and serially diluted with the corresponding Calibrator Diluent to fall within the assay's dynamic range.
Spike-and-dilution Linearity
To evaluate assay linearity, sample were spiked with high levels of Human FGF-21 in different matrices and serially diluted with the corresponding Calibrator Diluent to fall within the assay's dynamic range.
Intra-Assay Precision (Precision within an assay)
Three samples of known concentration were tested fifteen times on one plate to assess intra-assay precision.
Inter-Assay Precision (Precision between assays).
Three samples of known concentration were tested in separate assays to assess inter-assay precision. Assays were performed with at least three lots of components.
Determination of Minimum Detectable Dose (MDD)
The MDD was determined using three independent lots of assay components. For each lot, 19 replicate measurements of the diluent (zero calibrator) were performed. The mean (AVERAGE) and standard deviation (STDEV) of the 19 replicates were calculated. The MDD for each lot was then calculated according to the following formula:
MDD = 2 × STDEV + AVERAGE
HOOK Effect Threshold
The upper limit of the HOOK effect was established at 10× the highest calibrator concentration. No HOOK effect was observed below this threshold, confirming that samples within this concentration range yield reliable quantitative results without signal depression.
Protocol Diagram
