Featuring Dr. Richard Bebb, MD, ABIM, FRCPC, Endocrinologist

Duration: 3 minutes, 49 seconds

The treatment or replacement of thyroid hormone can be accomplished a number of different ways.

Most patients are fine, however, on levothyroxine. Levothyroxine is a synthetically derived but structurally identical hormone to the hormone that your body would produce normally.

Thyroids produce both levothyroxine and, sort of a long word, triiodothyronine, which is called T3 for short. Most of the time, giving levothyroxine, or T4, is sufficient replacement.

Levothyroxine, or T4, as we call it in shorthand, is an easy hormone to take. It has a very long half-life of about six days. You can take it orally once a day in the morning and every day, keeping on that dose schedule.

One of the issues is getting it taken regularly and also ensuring that you are getting it absorbed. It's actually a little more difficult than one might think to keep your thyroid levels normal.

The first issue is, there are certain compounds that impair the absorption of thyroid hormone, most notably, iron or calcium supplements. You shouldn't take your thyroid hormone at the same time as those, as it will impair the absorption and therefore your levels won't be normal.

In that group, it's probably wise to include multivitamins. The wisest time, the best time to take your thyroid hormone is in the morning before breakfast with a big glass of water. Do it that way every day to try and ensure you get the right dose and your blood levels stay normal.

There are some foods that also decrease the absorption. Soy milk is a notable one. If it's your habit to have your breakfast with soy milk and cereal and you've had your thyroid dose just before, that can be a problem.

Consistency is also an issue. Whichever way you take it, keep taking it regularly. It's important to periodically document by blood test. Again, the TSH test is the best test that your levels haven't drifted out of the normal range. At least once a year is wise once you're on replacement.

If you are prescribed iron or calcium supplements, it's easier to take it at a different time of the day, perhaps at dinner. If it's hard for you to remember to take medications later in the day, as long as it's a good hour after the thyroid medication, you shouldn't have a dramatic effect decreasing the absorption.

Another important issue is, there are a number of different brands of thyroid hormone, and not all of them are exactly interchangeable. If you switch brands, you should recheck your blood levels six weeks later to make sure you haven't drifted out of the normal range.

A little take-home pearl about thyroid hormone that's helpful for patients on long-term therapy: because it has such a long duration of action, you can actually double up if you miss a day. If you miss one day - this is quite unusual with agents - due to its long half-life, you can take two pills the following day and carry on. Most people won't feel a difference, and it won't hurt you.

If you have any further questions or want to discuss thyroid hormone replacement or other options, do check with your primary care practitioner.

Presenter: Dr. Richard Bebb, Endocrinologist, Victoria, BC

Local Practitioners: Endocrinologist