What is thyroid hormone replacement, and why do I need to take it regularly?

When you have hypothyroidism, your body does not have enough thyroid hormone. You may have symptoms such as feeling cold, fatigue, sleepiness, constipation, dry skin, weight gain, swelling, hoarseness, or irregular menstrual periods.

Your doctor will decide whether you need thyroid hormone replacement based on the cause, your age, body weight, heart condition, pregnancy status, and blood test results. The commonly used medication is levothyroxine, which replaces the thyroid hormone your body is missing.

Thyroid function usually does not return to normal right away. After a dose adjustment, it may take several weeks before the change is reflected in blood test results. Please take the medicine regularly and return for follow-up as instructed. Do not increase the dose or stop the medicine on your own.

How should I take thyroid hormone so it is absorbed well?

1. Take it at a fixed time every day. A common method is to take it in the morning on an empty stomach with plain water, then wait 30 to 60 minutes before eating.
2. If your doctor agrees, you may take it at bedtime, but it should be at least 3 to 4 hours after dinner or a snack. The key is to keep the same routine every day.
3. Calcium, iron, prenatal vitamins, antacids, stomach medicines, aluminum- or magnesium-containing stomach liquids, bile acid-binding medicines, and some phosphate-lowering medicines may interfere with absorption. They usually need to be separated from thyroid hormone by at least 4 hours. Please follow your doctor or pharmacist's instructions.
4. Coffee, milk, soy milk, high-fiber meals, or nutritional supplements taken too close to thyroid hormone may affect absorption. Please discuss the best schedule for you with your doctor.
5. If you forget a dose, do not take many tablets at once on your own. Ask your doctor or pharmacist what to do.

Why do blood tests still show that thyroid hormone replacement is not enough?

Common reasons include:

1. Missing doses, taking the medicine at inconsistent times, or changing the dose on your own.
2. Taking it too close to calcium, iron, stomach medicines, nutritional supplements, milk, or coffee.
3. A change in medication brand, formulation, or the way you take the medicine, which may change absorption.
4. Recent major weight change, pregnancy, gastrointestinal disease, kidney or liver disease, or a major acute illness, which may change the dose you need or affect how test results are interpreted.
5. Some medicines or supplements may affect thyroid hormone levels or test results, such as anti-seizure medicines, blood thinners, estrogen, some cholesterol-lowering medicines, and biotin. Please tell your doctor about all medicines and supplements you use.

When should I return earlier or have blood tests checked?

1. Symptoms do not improve, or you feel more cold, more tired, have worsening constipation, or gain weight noticeably.
2. You develop palpitations, hand tremor, heat intolerance, insomnia, or rapid weight loss, which may mean the dose is too high.
3. You are pregnant, planning pregnancy, postpartum, or have a noticeable weight change.
4. You start or stop a medicine or supplement that may affect thyroid hormone.
5. If you have chest pain, shortness of breath, an irregular heartbeat, or confusion, seek medical care immediately.

Your doctor usually arranges blood tests several weeks after starting treatment or changing the dose. After your condition is stable, follow-up will be scheduled according to your individual situation.

What should I pay attention to in daily life?

1. Thyroid hormone is the main treatment. Diet or supplements cannot replace the medicine.
2. Keep the same method of taking the medicine. If you need to change the brand, formulation, or timing, discuss it with your doctor or pharmacist first.
3. Bring all medicines, health supplements, and iodine-containing products you use to your doctor or pharmacist for review.
4. Treatment goals and doses may be different for people after thyroid cancer surgery, people with heart disease, older adults, or pregnant patients. Please follow your individualized medical instructions.
5. Do not use unregulated thyroid health supplements or animal thyroid extracts on your own.