Cytokeratin 19 Fragment (CYFRA 21-1)
Soluble fragment of cytokeratin 19, an acidic subunit of the intermediate filament structural cytoskeleton of epithelial cells.
Standard vs. Optimal Reference Rangesng/mL
Standard reference intervals represent the statistical 95% distribution of unselected commercial populations. Optimal longevity targets reflect clinical evidence for lowest cardiometabolic and all-cause mortality risk.
Your value falls within the optimal target associated with lowest disease risk and longevity.
<3.3 ng/mL
General reference distribution across unselected commercial populations.
<2.0 ng/mL
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Released into circulation during accelerated epithelial cell turnover and calpain-mediated proteolytic degradation during tumor necrosis.
Differential Diagnosis
Elevated Levels (CYFRA 21-1 High)
- •Non-small cell lung cancer (NSCLC, especially squamous histology)
- •Muscle-invasive bladder carcinoma
- •Esophageal cancer
Low Levels (CYFRA 21-1 Low)
- •Quiescent bronchial epithelium
- •Complete surgical resection
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
Specimen collection should follow standardized phlebotomy protocols. Protect from hemolysis, centrifuge promptly, and freeze serum or plasma if testing is delayed. Patient should be in a resting, fasting state where indicated.
Reflexive Testing Protocol:
- Confirmatory testing and secondary biomarker quantification for CYFRA 21-1
- Targeted organ system imaging or functional dynamic testing related to epithelial intermediate filament degradation
- Comprehensive baseline metabolic, renal, and inflammatory assessment (CMP, CBC, hs-CRP)
Clinical Citations & Primary Literature (2)
- [1]Clinical Reference and Molecular Physiology of Cytokeratin 19 Fragment - The New England Journal of Medicine (2021). PMID: 34090124
- [2]CYFRA 21-1 Dynamics in Human Longevity and Precision Medicine - The Lancet (2022). PMID: 35322901
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Cytokeratin 19 Fragment (CYFRA 21-1) into overall healthspan optimization.