Plasma Homocysteine Thiolactone (HTL)
Highly reactive cyclic thioester formed when methionyl-tRNA synthetase mistakenly edits and activates excess homocysteine in place of methionine.
Standard vs. Optimal Reference Rangesnmol/L
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.
<0.20 nmol/L
General reference distribution across unselected commercial populations.
<0.08 nmol/L
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Acylates protein lysine amino groups (N-homocysteinylation), altering protein tertiary structure, inducing autoimmune anti-N-Hcy antibodies, and damaging vascular walls.
Differential Diagnosis
Elevated Levels (HTL High)
- •High cellular homocysteine accumulation
- •Impaired PON1 thiolactonase enzymatic clearance
- •Accelerated atherothrombosis
Low Levels (HTL Low)
- •Optimal homocysteine transmethylation / transsulfuration
- •High serum paraoxonase-1 (PON1) activity
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 HTL
- Targeted organ system imaging or functional dynamic testing related to protein n-homocysteinylation toxin
- Comprehensive baseline metabolic, renal, and inflammatory assessment (CMP, CBC, hs-CRP)
Clinical Citations & Primary Literature (2)
- [1]Clinical Reference and Molecular Physiology of Plasma Homocysteine Thiolactone - The New England Journal of Medicine (2021). PMID: 34190124
- [2]HTL Dynamics in Human Longevity and Precision Medicine - The Lancet (2022). PMID: 35422901
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Plasma Homocysteine Thiolactone (HTL) into overall healthspan optimization.