Biomarker Validation Overview: SDMA, NT-proBNP, CRP, SAA¶
1. The Four Core Biomarkers¶
Migibio's FICT platform quantifies four clinically essential veterinary biomarkers. Each is validated for analytical performance and clinically interpreted against established reference ranges.
| Biomarker | Organ / System | Primary Use | Rise Window |
|---|---|---|---|
| CRP (canine) | Systemic inflammation | Infection/inflammation detection & monitoring | Hours |
| SAA (feline) | Systemic inflammation | Feline inflammation detection & monitoring | 3–6 h |
| SDMA | Kidney | Early CKD detection (muscle-mass independent) | Progressive |
| NT-proBNP | Heart | Cardiac disease detection & staging | Progressive |
2. Clinical Rationale Summary¶
2.1 CRP — Canine Acute-Phase Protein¶
- Major acute-phase protein in dogs (100× baseline rise).
- Serial CRP is the standard for monitoring therapy response.
- Distinguishes inflammatory from non-inflammatory disease.
2.2 SAA — Feline Acute-Phase Protein¶
- Major acute-phase protein in cats (faster rise than canine CRP).
- Reliable where fever is absent (common in cats).
- Elevated in FIP, pancreatitis, trauma, neoplasia.
2.3 SDMA — Renal Function¶
- Methylated arginine cleared by renal filtration.
- Unaffected by muscle mass — superior to creatinine in cachectic patients.
- Rises at ~40% GFR loss (creatinine ~75%) — true early detection.
2.4 NT-proBNP — Cardiac Function¶
- Released on myocardial stretch; gold-standard cardiac biomarker.
- Detects occult heart disease before radiographs change.
- Stages cardiac vs non-cardiac dyspnea.
3. Reference Ranges (Consolidated)¶
| Biomarker | Species | Normal | Grey Zone | Abnormal |
|---|---|---|---|---|
| CRP | Canine | < 10 mg/L | 10–40 mg/L | > 40 mg/L |
| SAA | Feline | < 5 µg/mL | 5–20 µg/mL | > 20 µg/mL |
| SDMA | Canine/Feline | 0–14 µg/dL | 14–18 µg/dL | > 18 µg/dL |
| NT-proBNP | Canine | < 900 pmol/L | 900–1800 pmol/L | > 1800 pmol/L |
4. Analytical Performance (Consolidated)¶
| Biomarker | LOD | Linear Range | Intra-assay CV% | Inter-assay CV% |
|---|---|---|---|---|
| CRP | 0.5 mg/L | 1–300 mg/L | < 8% | < 10% |
| SAA | 0.5 µg/mL | 1–250 µg/mL | < 8% | < 10% |
| SDMA | 0.5 µg/dL | 1–100 µg/dL | < 8% | < 10% |
| NT-proBNP | 15 pmol/L | 30–10,000 pmol/L | < 8% | < 10% |
5. Combined Diagnostic Logic¶
A single-visit panel combining these biomarkers provides:
- Inflammation status (CRP/SAA)
- Renal function (SDMA)
- Cardiac function (NT-proBNP)
This enables a rapid, data-driven triage of sick patients — especially in emergency and geriatric medicine where time-to-decision is critical.
References¶
- Nabity MB, Lees GE, Boggess MM, et al. Symmetric dimethylarginine assay validation, stability, and evaluation as a marker for the early detection of chronic kidney disease in dogs. J Vet Intern Med. 2015;29(4):1036-1044. PMID: 26079532
- Nakamura M, Takahashi M, Ohno K, et al. C-reactive protein concentration in dogs with various diseases. J Vet Med Sci. 2008;70(2):127-131. PMID: 18319571
- Kajikawa T, Furuta A, Onishi T, et al. Changes in concentrations of serum amyloid A protein, alpha 1-acid glycoprotein, haptoglobin, and C-reactive protein in feline sera due to induced inflammation and surgery. Vet Immunol Immunopathol. 1999;68(1):91-98. PMID: 10231954
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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.