- Dec 25, 2024
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⚖️ T4 Dosing Precision: The Art & Science of Thyroid Optimization
Why "One-Size-Fits-All" Fails With Levothyroxine
Why "One-Size-Fits-All" Fails With Levothyroxine
🧪 The Gold Standard: Weight-Based Initiation
The universally accepted starting dose is:
- 1.6 mcg/kg/day for healthy adults
- Example: 70kg person → 112mcg/day
- Always adjusted for:
→ Lean body mass (not total weight)
→ Residual thyroid function (TSH levels)
→ Cardiac risk factors
Pro Tip: Take fasting with water only - coffee reduces absorption by 30%
👵 Special Population Protocols
| Population | Dose Adjustment | Rationale |
|---|---|---|
| Elderly/Frail | 25-50mcg/day starting | • Slower metabolism • Cardiac sensitivity • Higher fracture risk |
| Pregnancy | +20-30% increase needed | • ↑ Thyroid-binding globulin • Fetal brain development demands |
| Post-Bariatric Surgery | May require 2-3x higher doses | • Malabsorption issues • Altered gut pH |
⚠️ Critical Dose Modifiers
- Medications That Reduce Absorption:
→ Calcium carbonate (30% reduction)
→ Iron sulfate (40% reduction)
→ PPIs (28% reduction)
Solution: Dose 4+ hours apart - Conditions Requiring Higher Doses:
→ Celiac disease
→ H. pylori infection
→ Lactose intolerance - Lifestyle Factors:
→ Vegan diets often need +15% dose
→ Heavy exercise may increase needs
🔄 Lifelong Adjustment Guide
| When to Reassess | Expected Change |
|---|---|
| Every 10 years after age 50 | +5-15mcg likely needed |
Weight change ±10kg
±12-25mcg adjustment
Starting/stopping estrogen
±20-30mcg change
Monitoring is Key: Get TSH tested every 6-8 weeks post-dose change, then annually when stable
💬 Discussion Starters:
1. What dosing strategy worked best for you?
2. Have you experienced absorption issues with other meds?
3. How often do you retest your thyroid levels?
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