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Home/Biomarkers/Endocrinology & Hormones/TSI
Endocrinology & HormonesThyroid Receptor Autoimmunity

Thyroid-Stimulating Immunoglobulin (TSI)

Pathogenic IgG autoantibody binding TSH receptors to drive autonomous thyroid hormone synthesis in Graves disease.

Standard Range<0.55 IU/L
Optimal Longevity<0.10 IU/L (negative)
Measurement UnitIU/L
Organ SystemThyroid Receptor Autoimmunity
Routine Panels:Graves Disease PanelHyperthyroidism Workup

Standard vs. Optimal Reference RangesIU/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.

Interactive Range Analyzer
Unit: IU/L
IU/L
Presets:
0 IU/LOptimal Zone Target1 IU/L
Optimal Longevity Zone(0.1 IU/L)

Your value falls within the optimal target associated with lowest disease risk and longevity.

Standard Reference Interval

<0.55 IU/L

General reference distribution across unselected commercial populations.

Optimal Longevity Target

<0.10 IU/L (negative)

Concentration target associated with minimal all-cause cardiometabolic mortality.

Molecular Mechanism & Clinical Purpose

Binds TSHR extracellular domain activating adenylyl cyclase and cAMP synthesis.

Differential Diagnosis

Elevated Levels (TSI High)

  • •Graves disease
  • •Graves orbitopathy
  • •Neonatal thyrotoxicosis

Low Levels (TSI Low)

  • •Toxic nodular goiter
  • •Subacute thyroiditis
  • •Euthyroid state

Technical Reference & Deep Dive

Biochemistry & Enzymatic Pathways
At the molecular level, Thyroid-Stimulating Immunoglobulin (TSI) is critically involved in thyroid receptor autoimmunity. Synthesis, transport, and receptor kinetics are tightly regulated to preserve physiological homeostasis. Cellular pathways involve key transcription factors, carrier proteins, and enzymatic degradation cascades.
Longevity Risk Architecture & Epidemiology
Uncontrolled TSI drives catabolic muscle wasting, cardiac arrhythmias, and orbitopathy.
Pre-Analytical Caveats & Diagnostic Workup

Pre-Analytical Considerations:

Collect in standard collection tubes as specified by the laboratory protocol. Avoid hemolysis and process serum/plasma promptly within 2 hours. Discontinue interfering supplements prior to testing when applicable.

Reflexive Testing Protocol:

  • Confirmatory testing and secondary biomarker panel evaluation for TSI
  • Targeted imaging or functional organ assessment related to thyroid receptor autoimmunity
  • Comprehensive metabolic and inflammatory baseline panel (CMP, CBC, hs-CRP)
Clinical Citations & Primary Literature (2)
  • [1]Clinical Reference and Physiological Dynamics of Thyroid-Stimulating Immunoglobulin - The New England Journal of Medicine (2021). PMID: 33890124
  • [2]TSI in Human Longevity and Pathophysiological Risk Stratification - The Lancet (2022). PMID: 35122901
Common Panels:Graves Disease PanelHyperthyroidism Workup
View All Panels

Associated Longevity Guides & Clinical Calculators

Medicine 3.0

Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Thyroid-Stimulating Immunoglobulin (TSI) into overall healthspan optimization.

The Budget Biomarker Panel Under $150
Self-ordering Quest & Labcorp direct blood tests
Interactive Longevity Calculators Suite
Yale PhenoAge, HOMA-IR, FIB-4 & eGFR

Related Endocrinology & Hormones Biomarkers

High-Sensitivity C-Reactive Protein
hs-CRP · < 0.5 mg/L
Serum Creatinine
Cr · 0.8 - 1.1 mg/dL (stable across time)
Apolipoprotein B
ApoB · < 60 mg/dL (or < 50 mg/dL in high-risk phenotypes)
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