Thyroid Replacement Medications
By April Segal PharmD
Here at Remedy, we get tons of questions on thyroid medications and thyroid conditions. Last week we posted an article by Anne, one of our Clinical Herbalists on herbs for thyroid support. Read it here if you missed it. Some patients may need more support than what herbs can provide, (or at least until they can address some of the root causes) and that is when thyroid replacement medications are used. There are a lot of nuances to finding the right thyroid medication product for you, and to make matters more complicated we see a lot of differences in how doctors prescribe thyroid replacement. We wanted to provide you with some basic information that will help you discuss thyroid medications with your doctor so that you can get the best results possible!
Thyroid Function Labs
Most doctors screen for TSH and free T4 levels. However this does not always tell you the entire story. If the only levels checked are TSH and free T4 levels, the labs may be normal but sometimes symptoms remain. This may be due to the body having difficulty converting from the inactive form (T4) to to the active form (T3). Your body can have trouble making this conversion due to adrenal fatigue or nutritional deficiency. It’s important to also ask your doctor to check for free T3 and reverse T3 as it may help with the following 3 scenarios:
- Difficulty converting T4 (inactive (storage)) to T3 (active)
- Converting too much T4 to T3
- Autoimmune thyroid condition
Testing for Thyroid Peroxidase Antibodies and Thyroglobulin Antibodies can also help rule out other autoimmune conditions, such as Hashimoto's Disease.
The following are the labs we recommend that you ask your doctor to measure (and optimum levels, although like we said you can't always rely on levels to tell you the whole story):
TSH: 1-2 UIU/ML or lower
Free T4: >1.1 NG/DL
Free T3: > 3.2 PG/mL
Reverse T3 <10:1 ratio RT3: FT3
Thyroid Peroxidase Antibodies < 4 IU/ML or negative
Thyroglobulin Antibodies < 4 IU/ML or negative
Thyroid Replacement Medications
Thyroid medications are dosed in very small amounts, micrograms. Thyroid replacement therapy may include manufactured medications or compounded preparations. Manufactured products may either be synthetic or desiccated. Doctors that prefer more natural options such as DOs or NDs typically prefer desiccated products.
Desiccated medications come from the dried thyroid glands of pigs. The reason that these are preferred by some doctors is because they provide both T3 and T4 (as well as T2, T1 and thyroglobulin, although these are less important than T3). Commercially available desiccated products include Armour Thyroid, Nature-Throid, NP Thyroid and WP thyroid. The differences between these medications mostly have to do with the inactive ingredients, including fillers and colors.
Synthetic medications can be either in the form of T4 or T3, but there is no commercially available combo T3/T4. T4 is bound in the body and is considered inactive as the body needs to convert the hormone to the active form, T3. T3 is the active form. Synthroid (or generic levothyroxine) Levoxyl, and Tirosint are all T4 forms of thyroid. Cytomel (or generic liothyronine) is a synthetic type of T3 hormone. If a doctor has you on T4 (levothyroxine) and wants to add T3 you would need to take a separate pill for this. There is no combination tablet of T3/T4 besides the dessicated products above or the custom made compounds we will discuss next.
Compound medications are customized medications made just for you. They offer a few advantages over both the desiccated or synthetic products, which made them preferred for certain patients. First of all they allow for custom dosings. Like we said previously, thyroid medications are dosed in very small doses (micrograms), that is because our bodies are very sensitive to these hormones and therefore very precise dosing is needed. Being able to take your blood levels and pick custom doses down to the microgram is a great advantage of custom thyroid medications.
Secondly, they can be prepared as a T4:T3 blend which allows you to have the benefit of T3 with the convenience of taking one capsule.
Lastly, we are also able to make longer-acting capsules (capsules that more slowly release the hormones). This is great for people who may be sensitive to the effects of T3, such as those with underlying heart conditions, as it allows for less of a “peak” effect after taking the medication. The altered release capsules have a specific ingredient (Methocel) which delays the absorption in the intestinal tract and provides a slow and steady absorption of T3 throughout the day. Sustained release compounds mirror the pattern of our own body’s natural hormones, releasing a slower rate similar to our own hormones. If you have tried synthetic T3 (Cytomel) or liothyronine and had adverse effects this may be a better option.
These compounds do not have portions of the thyroid like the desiccated porcine gland doses (T2, T1 and thyroglobulin) but do allow for more natural ratios of the T4:T3. Porcine ratio of T4:T3 is around 4.22:1 vs what is naturally found in humans which is about 11:1.
If you have questions on any of the products above or are wondering how to get a prescription for some of these products just come on in and speak with us or book a MedOp Consult!