FICT vs Colloidal Gold: Quantitative vs Qualitative Lateral Flow¶
Both FICT and colloidal gold are lateral-flow immunoassays — but they sit at opposite ends of the capability spectrum. This comparison explains the difference and when each wins.
The Fundamental Difference¶
| Attribute | Colloidal Gold | FICT |
|---|---|---|
| Readout | Visual line (human eye) | Fluorescence (instrument) |
| Result | Positive/negative | Numerical concentration |
| Detection limit | ~1 ng/ml | 0.01–0.1 ng/ml (pg/ml) |
| Dynamic range | 1–2 logs | 3–4 logs |
| Operator variability | High (visual judgment) | Low (instrument) |
| Cost | Low | Moderate (needs analyzer) |
What Quantitation Enables¶
The numerical result is not a cosmetic difference — it changes what you can do:
| Capability | Colloidal Gold | FICT |
|---|---|---|
| Disease staging (IRIS CKD) | No | Yes |
| Treatment monitoring (CRP trend) | No | Yes |
| Threshold decisions (NT-proBNP) | No | Yes |
| Screening (yes/no) | Yes | Yes |
When Each Wins¶
- Colloidal gold — pure screening where a yes/no answer suffices and cost dominates.
- FICT — any scenario requiring a number: staging, monitoring, or threshold-based decisions.
FAQ¶
Is FICT just "expensive colloidal gold"? No — the fluorescence signal and instrument readout are what enable quantitation and pg/ml sensitivity. It is a different capability class, not a premium version of the same thing.
When should I still use colloidal gold? For high-volume, low-cost screening where a qualitative answer is sufficient and no number is needed.
For the full three-way comparison, see FICT vs ELISA vs PCR.
Authored by: Migibio Clinical & Scientific Affairs, Guangzhou Magic Biotech Co., Ltd.
Reviewed by: Migibio R&D Quality Committee
Last updated: 2026-08-13
Disclosure: Migibio (Guangzhou Magic Biotech Co., Ltd.) is the manufacturer of the FIA680/FIA880 analyzers and FICT reagents referenced in this content. See our Editorial & Review Policy.