Welcome, Lin. You are correct: Synthroid is a T4-only med, and Cytomel is a T3-only med. Our bodies typically need both because they are absorbed in different areas, but during the metabolism process T4 breaks down to form T3 (and then to T2 and T1 I believe, though these forms of the hormone aren't tested).
Adjustments to T4 meds take about 6-8 weeks to fully assimilate in our body. But T3 meds (considered "fast-acting") are more readily absorbed and more easily used up as well. Because of this, T3-only therapy sometimes produces symptoms of Hyper when you first take your dose, and then Hypo later in the day when you've used it up. Most people split the dose throughout the day to minimize this problem.
With Hypo patients with low T3 levels, some doctors prescribe T4-only meds, with the belief that increasing the doseage will provide the body with the T3 it needs. It works for some; others need to supplement their bodies with additional T3 -- combination therapy (Synthroid + Cytomel) works best for these folks. Still others are on T3-only meds. This protocol is typically followed for those with Wilson's Syndrome (where the body is producing Reverse T3).
Ask your doctor to test your blood levels for (at a minimum) Free T3, Free T4, Reverse T3, TSH, and Thyroid Antibodies. The Free T3/T4 levels will show how much of the hormone is available to the body for use -- other blood tests include the hormone that's bound to proteins and is sometimes an inaccurate depiction of what's going on.
Thyroid antibodies are interesting because antibody-related thyroiditis (including Hashimoto's) may cause fluctuations in your blood levels, particularly the TSH, and may also cause your symptoms to flare up sometimes as Hypo, Hyper or a combination of both.
Medications are typically prescribed according to the protocol about which the doctor has the most knowledge. This is generally a pretty good idea, as the patient is more likely to receive relief from something the doc has experience with, but there are cases where new methods are necessary. Your doc may not be familiar with T4/T3 combination therapy and, as such, is less comfortable with the idea. But T3-only can be difficult to manage at times.
If you've not yet had a chance, read through our Information Archive thread. It includes symptoms lists, notes about various tests and what they mean, thyroiditis and antibodies, supplements that may be helpful (such as Vitamin B-complex, Selenium and Maca), questions to ask doctors, and much more.
Information Archive thread [url="http://www.healthboards.com/ubb/Forum118/HTML/000005.html"]http://www.healthboards.com/ubb/Forum118/HTML/000005.html[/url]
Let us know what happens.
questions about cytomel
Linear Mode
