TOBIN Intelligence Library · evidence review
Hypothyroidism & Hashimoto's Thyroiditis
Primary hypothyroidism is most often autoimmune (Hashimoto's thyroiditis). It is diagnosed by TSH with free T4, and anti-TPO antibodies identify the autoimmune form. Iodine status, selenium, iron, pregnancy and certain medications all modify thyroid function.
What is well established
3 links- Thyroid autoimmunity (anti-TPO) → Progressive loss of thyroid hormone outputA
Lymphocytic infiltration destroys thyroid follicles; anti-TPO positivity predicts progression to overt hypothyroidism (Whickham survey).
Established causal · Multiple high-quality guidelines or meta-analyses
- Iodine deficiency or excess → Altered thyroid hormone synthesisA
Iodine is required for T4/T3 synthesis; both deficiency and excess can trigger hypothyroidism in susceptible people.
Established causal · Multiple high-quality guidelines or meta-analyses
- Hypothyroidism → Raised LDL and weight gainA
Reduced LDL-receptor expression and lower basal metabolic rate; corrected by levothyroxine.
Established causal · Multiple high-quality guidelines or meta-analyses
What is suspected, not proven
1 links- Perchlorate and other thyroid-active chemicals → Reduced iodide uptakeC
Perchlorate competitively inhibits the sodium-iodide symporter; NHANES links urinary perchlorate with TSH in low-iodine women. Detection is not proof of effect.
Open question: the exposure is measurable, but whether it contributes at real-world levels needs prospective human data.
iDetection of an exposure does not establish that it caused a disease. This platform separates exposure, association, plausible mechanism, clinical evidence and demonstrated causation.
Domain emphasis
Infection triggers for thyroid autoimmunity remain hypotheses; no antimicrobial treatment is indicated for Hashimoto's.
Related Quadpandemics
I · Estrogen & Endocrine Disruption
Endocrine-active chemicals are widely measurable in the population; their health effects must be evaluated exposure by exposure.
II · Obesity & Metabolic Dysfunction
Obesity is a signaling and exposure problem, not a number on a scale.
III · Allergy & Immune Dysregulation
Allergic and immune-complex disease is the fastest-rising chronic burden of the century.
IV · Anxiety, Depression & Neurobehavioral Health
Mood symptoms are assessed responsibly — never automatically attributed to toxins or hormones.
Labs that inform this review
- Fasting insulin (2.0–8.0 µIU/mL) — Insulin signaling load; pairs with glucose for HOMA-IR. Marked elevation with symptoms warrants clinician review.
- ApoB (< 90 (lower if high risk) mg/dL) — Atherogenic particle count; better risk discrimination than LDL-C alone. Persistently high values deserve a cardiovascular risk discussion.
- hs-CRP (< 1.0 mg/L) — Non-specific inflammatory burden. Values above 10 mg/L usually indicate an acute process needing evaluation.
- TSH (0.4–4.0 mIU/L) — First-line thyroid signaling test. Any abnormal result should be confirmed and reviewed clinically.
- Estradiol (Cycle- and sex-dependent pg/mL) — Central to Pandemic I assessment, interpreted with cycle timing. Interpretation requires a clinician who knows your cycle and medication context.
- Free T4 (0.8–1.8 ng/dL) — Circulating thyroid hormone; confirms whether an abnormal TSH reflects true thyroid under- or over-function. Low free T4 with symptoms, or any high value with palpitations, needs clinician review promptly.
- Free T3 (2.3–4.2 pg/mL) — Active thyroid hormone, formed mostly by conversion of T4 in tissues. High free T3 with low TSH suggests hyperthyroidism — see a clinician.
- Reverse T3 (9–24 ng/dL) — Inactive T4 metabolite that rises in stress, illness and calorie restriction. Do not change thyroid medication on rT3 alone; discuss with a clinician.
- Anti-TPO antibodies (< 35 (assay-specific) IU/mL) — Thyroid peroxidase antibodies — the main marker of autoimmune (Hashimoto's) thyroiditis. Positive antibodies in pregnancy or with rising TSH deserve clinician follow-up.
- Thyroglobulin antibodies (≤ 4 (assay-specific) IU/mL) — Second autoimmune thyroid marker; occasionally positive when anti-TPO is negative. Review with a clinician alongside TSH and free T4.
- Lp-PLA2 activity (≤ 123 nmol/min/mL) — Vascular-specific inflammatory enzyme (PLAC test, FDA-cleared). Review with a clinician as part of cardiovascular risk.
Score cutoffs used
- HbA1c ADA Standards of Care: 5.7–6.4% prediabetes, ≥6.5% diabetes range
- Fasting insulin Common functional reference; interpret only with a true fasting sample
- hs-CRP AHA/CDC: <1 lower, 1–3 average, >3 higher cardiovascular-inflammatory risk; >10 suggests acute process
- TSH ATA/Endocrine Society: 0.4–4.5 mIU/L; >10 overt range
- Ferritin AGA 2020: ferritin <45 ng/mL supports iron deficiency; WHO <15 depleted
- Eosinophils (absolute) >500 cells/µL eosinophilia; ≥1500 hypereosinophilia
- Total IgE Adult reference typically <100 IU/mL; context-dependent
- White blood cells Reference ≈ 4.0–11.0 ×10³/µL
- Free T4 Typical reference 0.8–1.8 ng/dL (assay-specific); interpret with TSH (ATA)
- Free T3 Typical reference 2.3–4.2 pg/mL; low T3 also occurs in illness and calorie restriction
- Reverse T3 Typical reference 9–24 ng/dL; guidelines (ATA) do not recommend rT3 for routine diagnosis — grade D
- Anti-TPO antibodies Common cutoff >34–35 IU/mL (assay-specific); marks Hashimoto's risk (ATA)
- Thyroglobulin antibodies Common cutoff ≤4 IU/mL (Roche) — assay-specific; positive in ~60–80% of Hashimoto's
- Small LDL-P NMR LipoProfile: ≤527 nmol/L reference
- LDL particle size NMR: >20.5 nm pattern A, ≤20.5 pattern B
- sdLDL-C (small dense LDL) Denka assay (Quest Cardio IQ, Boston Heart): <30 mg/dL optimal (lab-specific)
- Lp-PLA2 activity PLAC Activity test (FDA-cleared): >123 nmol/min/mL higher risk
Key formulas and thresholds
Published clinical cutoffs- HOMA-IR = fasting glucose (mg/dL) × fasting insulin (µIU/mL) ÷ 405 — above 2.5 suggests insulin resistance (Matthews 1985).
- BMI = weight (kg) ÷ height (m)² — 25–29.9 overweight, 30 or more obesity (WHO); lower cutoffs (23/27.5) for many Asian populations.
- Waist-to-height ratio = waist ÷ height — 0.5 or more signals central adiposity (NICE 2022).
- TG/HDL ratio = triglycerides ÷ HDL (mg/dL) — above 3 is associated with insulin resistance (observational).
- HbA1c (%): concern above 5.6, scored 100 at 8 — ADA Standards of Care: 5.7–6.4% prediabetes, ≥6.5% diabetes range
- Fasting insulin (µIU/mL): concern above 8, scored 100 at 40 — Common functional reference; interpret only with a true fasting sample
- hs-CRP (mg/L): concern above 1, scored 100 at 10 — AHA/CDC: <1 lower, 1–3 average, >3 higher cardiovascular-inflammatory risk; >10 suggests acute process
- TSH (mIU/L): concern above 4.5, scored 100 at 20; concern below 0.4, scored 100 at 0.01 — ATA/Endocrine Society: 0.4–4.5 mIU/L; >10 overt range
- Ferritin (ng/mL): concern below 30, scored 100 at 5; concern above 300, scored 100 at 1000 — AGA 2020: ferritin <45 ng/mL supports iron deficiency; WHO <15 depleted
- Eosinophils (absolute) (cells/µL): concern above 500, scored 100 at 3000 — >500 cells/µL eosinophilia; ≥1500 hypereosinophilia
- Total IgE (IU/mL): concern above 100, scored 100 at 1000 — Adult reference typically <100 IU/mL; context-dependent
- White blood cells (×10³/µL): concern above 11, scored 100 at 20 — Reference ≈ 4.0–11.0 ×10³/µL
- Free T4 (ng/dL): concern below 0.9, scored 100 at 0.5; concern above 1.8, scored 100 at 3.5 — Typical reference 0.8–1.8 ng/dL (assay-specific); interpret with TSH (ATA)
- Free T3 (pg/mL): concern below 2.5, scored 100 at 1.8; concern above 4.4, scored 100 at 7 — Typical reference 2.3–4.2 pg/mL; low T3 also occurs in illness and calorie restriction
- Reverse T3 (ng/dL): concern above 24, scored 100 at 40 — Typical reference 9–24 ng/dL; guidelines (ATA) do not recommend rT3 for routine diagnosis — grade D
- Anti-TPO antibodies (IU/mL): concern above 34, scored 100 at 500 — Common cutoff >34–35 IU/mL (assay-specific); marks Hashimoto's risk (ATA)
- Thyroglobulin antibodies (IU/mL): concern above 4, scored 100 at 200 — Common cutoff ≤4 IU/mL (Roche) — assay-specific; positive in ~60–80% of Hashimoto's
- Small LDL-P (nmol/L): concern above 527, scored 100 at 1000 — NMR LipoProfile: ≤527 nmol/L reference
- LDL particle size (nm): concern below 20.5, scored 100 at 19.5 — NMR: >20.5 nm pattern A, ≤20.5 pattern B
- sdLDL-C (small dense LDL) (mg/dL): concern above 30, scored 100 at 60 — Denka assay (Quest Cardio IQ, Boston Heart): <30 mg/dL optimal (lab-specific)
- Lp-PLA2 activity (nmol/min/mL): concern above 123, scored 100 at 225 — PLAC Activity test (FDA-cleared): >123 nmol/min/mL higher risk
iThese thresholds organize where to look; they do not diagnose. Laboratory ranges, age, sex and pregnancy change interpretation.