Hypothyroidism Conversion Made Simple
If you’ve been diagnosed with hypothyroidism, chances are you’ve heard doctors talk about levothyroxine, liothyronine, or a combo of both. Switching meds or adjusting the dose can feel like decoding a secret code. The good news? It isn’t as scary as it looks. In this guide we’ll break down how to convert doses, why you might switch, and what to watch out for.
How to Convert Levothyroxine Doses
Levothyroxine (T4) is the most common thyroid pill. It comes in micrograms—usually 25, 50, 75, 100, 125, or 150 µg. If you need a tiny tweak, most doctors will add or subtract 12.5 µg, which is half a 25‑µg tablet. You can split a 50‑µg tablet in half, but only if the tablet is scored. Never guess; use a pill cutter for an even split.
When you move to a higher dose, the rule of thumb is to increase by 12.5–25 µg every 4–6 weeks, then retest your TSH. Too fast and you might feel jittery; too slow and you stay sluggish. A quick way to estimate a new dose is: Current dose + (Target TSH change × 10). It’s not exact, but it gives a ballpark.
Switching Between Thyroid Medications Safely
Some people don’t feel right on levothyroxine alone. That’s when liothyronine (T3) or a combined T4/T3 pill enters the picture. Converting isn’t a 1:1 swap. Roughly, 100 µg of levothyroxine equals about 5 µg of liothyronine, but the body processes T3 much faster, so the dose feels stronger.
To make the switch, doctors usually cut the levothyroxine dose in half and add a low liothyronine dose (often 5 µg). They’ll monitor symptoms and blood work closely for the first few weeks. If you’re on a brand‑name combo pill, the conversion chart on the label can be a handy reference.
Remember, timing matters. Take levothyroxine on an empty stomach, wait 30‑60 minutes before breakfast, and if you add liothyronine, it’s often best taken midday to avoid sleep disturbances.
Final tip: keep a symptom diary. Note energy levels, weight changes, heart rate, and how you feel after meals. Pair that with regular TSH tests and you’ll have solid data to guide any dose tweak.
Converting hypothyroidism medication doesn’t have to be a mystery. With the right calculators, a bit of patience, and close communication with your doctor, you’ll find the sweet spot for your thyroid health.
