Thyroid Function Trend Tables
Purpose
The purpose of this section is to document thyroid-related laboratory changes over time and provide a clear visual representation of thyroid replacement effectiveness and hormone balance.
The primary thyroid markers reviewed are:
- Thyroid-Stimulating Hormone (TSH)
- Free Thyroxine (Free T4)
- Free Triiodothyronine (Free T3)
- Thyroid Antibodies
These markers help evaluate:
- Effectiveness of thyroid replacement therapy.
- Thyroid hormone availability.
- Thyroid stability.
- Possible autoimmune thyroid activity.
Thyroid History
Condition
Hypothyroidism
Current Treatment
Levothyroxine — 75 mcg daily
The purpose of replacement therapy is to maintain adequate thyroid hormone availability and prevent symptoms associated with low thyroid function.
Table 1 — Thyroid-Stimulating Hormone (TSH) Trend
| Date | Laboratory | TSH Result | Interpretation |
|---|---|---|---|
| June 2024 | Labcorp | 0.819 μIU/mL | Normal thyroid control |
| November 2024 | Labcorp | 1.110 μIU/mL | Stable thyroid replacement |
| November 2025 | Function Health / Quest | Normal | Continued control |
| June 2026 | Function Health / Quest | Normal | Stable thyroid function |
TSH Trend Summary
TSH has remained consistently controlled while taking levothyroxine.
Current interpretation:
✓ Thyroid replacement appears effective.
✓ No evidence of under-treatment.
✓ No evidence of significant over-treatment.
Table 2 — Free T4 Trend
| Date | Laboratory | Free T4 Result | Interpretation |
|---|---|---|---|
| June 2024 | Labcorp | 1.31 ng/dL | Normal thyroid hormone availability |
| November 2024 | Labcorp | 1.24 ng/dL | Stable replacement level |
| November 2025 | Function Health / Quest | Normal | Stable |
| June 2026 | Function Health / Quest | Normal | Stable |
Free T4 Trend Summary
Free T4 levels have remained within a healthy range.
This supports:
✓ Adequate thyroid hormone replacement.
✓ Stable circulating thyroxine availability.
✓ Consistent thyroid management.
Table 3 — Free T3 Trend
| Date | Laboratory | Free T3 Result | Interpretation |
|---|---|---|---|
| November 2025 | Function Health / Quest | Below reference range | Lower active thyroid hormone level identified |
| June 2026 | Function Health / Quest | Below reference range | Persistent lower Free T3 pattern |
Free T3 Trend Summary
Free T3 represents the active thyroid hormone available to tissues.
The persistent finding is:
- Lower Free T3.
- Normal TSH.
- Normal Free T4.
This creates a pattern requiring interpretation rather than immediate assumption of thyroid failure.
Possible contributing factors include:
- Individual thyroid hormone conversion differences.
- Aging-related changes.
- Low-carbohydrate nutritional patterns.
- Fasting or metabolic adaptation.
Table 4 — Thyroid Antibody Trend
| Date | Laboratory | Finding | Interpretation |
|---|---|---|---|
| 2025 | Function Health / Quest | Thyroid antibodies negative | No evidence of autoimmune thyroid disease |
| 2026 | Function Health / Quest | Thyroid antibodies negative | Continued absence of thyroid autoimmune markers |
Thyroid Antibody Summary
The absence of thyroid antibodies is an important finding because of the broader autoimmune history.
Current interpretation:
✓ Hypothyroidism is controlled.
✓ No laboratory evidence of autoimmune thyroid destruction.
Table 5 — Complete Thyroid Trend Summary
| Time Period | Major Findings | Overall Assessment |
|---|---|---|
| Earlier years | Hypothyroidism managed with medication | Stable condition |
| 2024 | Normal TSH and Free T4 | Effective replacement |
| 2025 | Lower Free T3 identified | Additional monitoring needed |
| 2026 | Persistent Free T3 pattern with normal TSH/Free T4 | Stable thyroid control |
Overall Thyroid Assessment
The thyroid trend demonstrates effective management of hypothyroidism.
Major Strengths
✓ Normal TSH
✓ Normal Free T4
✓ Stable levothyroxine therapy
✓ Negative thyroid antibodies
Area for Continued Monitoring
Lower Free T3 Pattern
The current question is not whether thyroid replacement is working—it is:
How should a lower Free T3 level be interpreted when TSH and Free T4 remain normal?
This should be considered alongside:
- Symptoms.
- Energy level.
- Metabolic health.
- Weight stability.
- Cardiovascular history.
Relationship to Other Health Trends
Thyroid and Cardiovascular Health
Thyroid hormone levels influence:
- Heart rhythm.
- Cholesterol metabolism.
- Cardiovascular function.
Because of your history of:
- Atrial fibrillation.
- Hypertension.
- Lipid monitoring.
continued thyroid monitoring remains appropriate.
Thyroid and Metabolic Health
The thyroid trend should also be interpreted alongside:
✓ Normal A1c
✓ Very low insulin
✓ Favorable triglycerides
✓ Excellent metabolic markers
The overall metabolic picture remains strong.
Clinical Significance
The thyroid trend demonstrates a stable and well-managed condition.
The overall conclusion is:
Thyroid replacement therapy is providing excellent control of standard thyroid markers. The persistent lower Free T3 pattern should continue to be monitored and interpreted within the context of symptoms, metabolic health, and overall clinical status.
Physician Discussion Points
Questions for Dr. George
- Should Free T3 continue to be monitored along with TSH and Free T4?
- Does the lower Free T3 value require intervention or continued observation?
- Could dietary pattern, fasting, or metabolic adaptation influence Free T3 levels?
Questions for Dr. Yoo
- Is the current thyroid replacement level appropriate given the history of atrial fibrillation?
- Should thyroid levels be considered when evaluating cardiovascular risk?
Related Sections
This trend table connects directly with:
- Section 3.5 — Hypothyroidism
- Section 3.6 — Autoimmune Serology
- Section 7.2.7 — Thyroid Trends
- Section 7.3.3 — Cardiovascular Trend Tables
- Section 7.3.4 — Metabolic Trend Tables
Navigation
Previous Section: Section 7.3.5 — Kidney Function Trend Tables
Current Section: Section 7.3.6 — Thyroid Function Trend Tables
Next Section: Section 7.3.7 — Nutritional Trend Tables
Return to Section 7 — Laboratory Archive
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