THYROID PANEL
INTERPRETER
Your thyroid controls metabolism, energy, and countless bodily functions. Enter your TSH, Free T4, and Free T3 values to understand what they mean using functional medicine optimal ranges.
// ENTER YOUR VALUES
Thyroid Stimulating Hormone - controls thyroid output
The storage hormone - converts to active T3
The active hormone - drives metabolism
// INTERPRETATION
TSH
--
mIU/L
FREE T4
--
ng/dL
FREE T3
--
pg/mL
T3:T4 RATIO
--
CONVERSION STATUS
--
Key insight: TSH alone doesn't tell the whole story. Free T3 is the active hormone that affects how you feel, while TSH reflects the brain's perception of thyroid function.
// THYROID_RANGES
STANDARD VS. OPTIMAL RANGES
| MARKER | STANDARD RANGE | FUNCTIONAL OPTIMAL | NOTES |
|---|---|---|---|
| TSH | 0.4-4.0 mIU/L | 1.0-2.0 mIU/L | Lower in range often associated with better energy |
| Free T4 | 0.8-1.8 ng/dL | 1.1-1.5 ng/dL | Mid-to-upper range provides adequate T3 substrate |
| Free T3 | 2.3-4.2 pg/mL | 3.0-4.0 pg/mL | Upper-half range optimal for metabolism and energy |
| T3:T4 Ratio | -- | 0.27-0.33 | Indicates healthy T4 to T3 conversion |
// THYROID_SCIENCE
UNDERSTANDING YOUR THYROID
HOW THE THYROID WORKS
Your thyroid is a butterfly-shaped gland in your neck that controls metabolism. The brain's pituitary gland releases TSH to signal the thyroid to produce hormones. The thyroid primarily makes T4 (inactive), which converts to T3 (active) in tissues throughout your body.
TSH: THE FEEDBACK SIGNAL
TSH (Thyroid Stimulating Hormone) works inversely - high TSH means your brain is shouting at a sluggish thyroid, while low TSH means there's plenty of hormone and the brain is quiet. This is why high TSH suggests hypothyroidism and low TSH suggests hyperthyroidism.
FREE T4 VS. FREE T3
- Free T4 (Thyroxine): The storage hormone. Produced directly by the thyroid. Serves as a reservoir to be converted to active T3.
- Free T3 (Triiodothyronine): The active hormone. 3-4x more metabolically potent than T4. Directly affects energy, metabolism, heart rate, and body temperature.
- Why "Free": Measures the unbound, bioavailable hormone, not the total amount bound to proteins.
SYMPTOMS OF LOW THYROID (HYPOTHYROIDISM)
- Fatigue: Persistent tiredness despite adequate sleep
- Weight gain: Unexplained weight gain or difficulty losing weight
- Cold intolerance: Feeling cold when others are comfortable
- Brain fog: Difficulty concentrating and poor memory
- Dry skin and hair: Hair loss, brittle nails
- Constipation: Slowed digestive function
- Depression: Low mood and motivation
SYMPTOMS OF HIGH THYROID (HYPERTHYROIDISM)
- Anxiety and irritability: Nervousness, restlessness
- Weight loss: Unexplained weight loss despite good appetite
- Heat intolerance: Feeling hot, excessive sweating
- Rapid heart rate: Palpitations, increased pulse
- Tremor: Shaky hands
- Insomnia: Difficulty sleeping
POOR T4 TO T3 CONVERSION
Some people have normal TSH and T4 but low Free T3, indicating a conversion problem. Factors that impair conversion include:
- Chronic stress: High cortisol inhibits T4 to T3 conversion
- Nutrient deficiencies: Selenium, zinc, and iron are required for conversion
- Inflammation: Promotes conversion to reverse T3 instead of active T3
- Calorie restriction: Severe dieting slows thyroid function
- Liver dysfunction: Much of T4 to T3 conversion occurs in the liver
ADDITIONAL MARKERS TO CONSIDER
- Thyroid antibodies (TPO, TgAb): Detect autoimmune thyroid disease
- Reverse T3: Inactive T3 that can block T3 receptors
- Total T3/T4: Protein-bound plus free hormone
Important: This tool is for educational purposes only. Thyroid levels must be interpreted by a healthcare provider in context with symptoms, medical history, and other factors. Do not start, stop, or adjust thyroid medication based solely on this information.
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