Thyroid
The butterfly-shaped gland that controls your metabolism, energy, and development. Thyroid hormones influence virtually every cell in your body.
🦋 How Thyroid Hormones Are Made
The thyroid gland concentrates iodine from the bloodstream and combines it with the amino acid tyrosine to create thyroid hormones. This process requires multiple nutrients and enzymes:
Sodium-iodide symporter pulls iodine into thyroid cells
TPO enzyme (needs iron) oxidizes iodide using H₂O₂
Iodine attached to tyrosine residues on thyroglobulin
Iodinated tyrosines couple to form T4 (and some T3)
🔄 T4 to T3 Conversion: Where the Magic Happens
The thyroid mainly produces T4, which is a "storage" hormone. T4 must be converted to T3 (the active form) in peripheral tissues by deiodinase enzymes. This conversion is selenium-dependent.
D1 Deiodinase
Liver, kidney, thyroid. Converts T4 → T3 for circulation.
D2 Deiodinase
Brain, pituitary, muscle. Local T3 production where needed.
D3 Deiodinase
Inactivates T4 → rT3. Upregulated in illness, stress.
Poor conversion (low T3, high rT3) can cause hypothyroid symptoms despite "normal" TSH and T4.
🔻 Hypothyroid Symptoms
Too little thyroid hormone slows everything down:
- • Fatigue, exhaustion
- • Weight gain, difficulty losing weight
- • Cold intolerance
- • Constipation
- • Depression, brain fog
- • Dry skin, hair loss
- • Muscle weakness, aches
- • Slow heart rate
- • Elevated cholesterol
- • Menstrual irregularities
🔺 Hyperthyroid Symptoms
Too much thyroid hormone speeds everything up:
- • Anxiety, nervousness, irritability
- • Weight loss despite increased appetite
- • Heat intolerance, excessive sweating
- • Rapid/irregular heartbeat (palpitations)
- • Tremor (shaky hands)
- • Insomnia
- • Frequent bowel movements
- • Muscle weakness
- • Light or absent periods
- • Eye problems (Graves')
🧬 Essential Thyroid Nutrients
Iodine
The literal building block. T4 = 4 iodines, T3 = 3 iodines. Deficiency causes goiter and hypothyroidism.
Selenium
Required for all three deiodinases (T4→T3 conversion) and glutathione peroxidase (protects thyroid from H₂O₂).
Iron
TPO enzyme requires iron. Iron deficiency impairs thyroid hormone synthesis.
Zinc
Needed for thyroid hormone synthesis, T4→T3 conversion, and thyroid receptor binding.
Vitamin A
Regulates TSH secretion and thyroid hormone metabolism. Works with thyroid receptors.
Tyrosine
Amino acid backbone of thyroid hormones. Usually adequate from diet.
⚠️ Thyroid Autoimmunity
Most thyroid disease in developed countries is autoimmune. The immune system attacks thyroid tissue:
Hashimoto's Thyroiditis
- • Most common cause of hypothyroidism
- • Antibodies: anti-TPO, anti-thyroglobulin
- • Gradual thyroid destruction
- • Often starts with hyper phase, then hypo
- • Associated with gluten sensitivity
Graves' Disease
- • Most common cause of hyperthyroidism
- • TSH receptor stimulating antibodies
- • Causes thyroid overproduction
- • May cause eye disease (ophthalmopathy)
- • Can fluctuate between hyper and hypo
Supporting autoimmune thyroid: Selenium may reduce antibody levels. Address gut health (leaky gut linked to autoimmunity). Consider gluten elimination. Manage stress. Ensure adequate vitamin D. Address underlying infections.
🧪 Complete Thyroid Panel
TSH alone is insufficient. A complete picture requires:
TSH
Pituitary signal. High = hypo, low = hyper. Optimal: 1-2 mIU/L.
Free T4
Unbound storage hormone. Shows thyroid output.
Free T3
Active hormone. Shows conversion ability. Critical for symptoms.
Reverse T3
Inactive form. High rT3 = conversion problem (stress, illness).
TPO Antibodies
Hashimoto's marker. Elevated = autoimmune attack.
Thyroglobulin Ab
Another Hashimoto's marker. Can be elevated alone.
Metabolic Connections
Iodine
Structural component of T4 and T3—thyroid hormones are literally made of iodine
Selenium
Required for deiodinases that convert T4 to active T3
Iron
TPO enzyme requires iron—deficiency mimics hypothyroidism
Zinc
Needed for thyroid hormone synthesis and receptor function
Cortisol
Chronic stress suppresses thyroid function and T4→T3 conversion
Tyrosine
Amino acid backbone of thyroid hormones