Levothyroxine is a synthetic version of thyroxine (T4), a hormone produced by the thyroid gland. It is prescribed to treat hypothyroidism, a condition where the thyroid does not produce enough hormone. By replacing the deficient hormone, it restores the body's metabolic rate and resolves symptoms like fatigue, weight gain, and cold intolerance.
Verdict
Essential for hypothyroidism treatment; inappropriate and dangerous for general healthspan enhancement.
HEALTHSPAN IMPACT
Foundational
RISK LEVEL
Moderate
EVIDENCE GRADE
A
MONTHLY COST
$4 - $30
Protocol
- Dosage is highly individualized based on TSH blood tests, age, and weight, typically starting at 25-50 mcg daily.
- Doses are adjusted by a physician every 4-8 weeks until TSH is within the target range.
- Taken once daily on an empty stomach, 30-60 minutes before the first meal of the day.
Flags
- Must be prescribed and monitored by a physician via regular blood tests.
- Over-treatment can induce hyperthyroidism, causing atrial fibrillation, anxiety, and osteoporosis.
- Has a narrow therapeutic index, meaning small dose changes can have significant effects.
- Absorption is significantly reduced by food, calcium, iron supplements, and antacids.
- Not a weight-loss or healthspan drug for individuals with normal thyroid function.