# Lower dosage and best way to start it



## luvmylittleboy2003 (Aug 23, 2011)

My Dr lowered my dose from .100 to .88. What is the best way to adjust. I've read stopping the syntroid for a few days then restarting has been best for some, but, others say to continue as is..just with the lower dosing. How long before I start feeling the change...hopefully quick!!


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## northernlite (Oct 28, 2010)

Just start the lower dose. Levothyroxine has a long half life. So it takes awhile before you notice the change. My personal experience is I start to feel a change (either good or bad depending on what they are doing with my dosage) in 7-12 days and what every I am feeling then becomes more consistent over the next two weeks. At times, I have noticed improvements when increasing medications for 8-9 weeks after.


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## webster2 (May 19, 2011)

What does half life mean?


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## Andros (Aug 26, 2009)

webster2 said:


> What does half life mean?


half-life (hflf, häf-)
n.
1. Physics The time required for half the nuclei in a sample of a specific isotopic species to undergo radioactive decay.
2. Biology 
a. The time required for half the quantity of a drug or other substance deposited in a living organism to be metabolized or eliminated by normal biological processes. Also called biological half-life.
b. The time required for the radioactivity of material taken in by a living organism to be reduced to half its initial value by a combination of biological elimination processes and radioactive decay.

For example, if one starts with 100 grams of radium 229, whose half-life is 4 minutes, then after 4 minutes only 50 grams of radium will be left in the sample, after 8 minutes 25 grams will be left, after 12 minutes 12.5 grams will be left, and so on.

You will laugh; I had to turn to good ol' Webster for this one!! Hee, hee!


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## webster2 (May 19, 2011)

Andros said:


> half-life (hflf, häf-)
> n.
> 1. Physics The time required for half the nuclei in a sample of a specific isotopic species to undergo radioactive decay.
> 2. Biology
> ...


LOL, I did laugh, than did the V-8 smack...I don't know why I didn't think of that! Thank you! As always, you are wonderful!


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## Andros (Aug 26, 2009)

webster2 said:


> LOL, I did laugh, than did the V-8 smack...I don't know why I didn't think of that! Thank you! As always, you are wonderful!


I love it; I love looking things up and learning! If I am wonderful it is only because I am surrounded by wonderful and loving people on this board!


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## webster2 (May 19, 2011)

Andros said:


> I love it; I love looking things up and learning! If I am wonderful it is only because I am surrounded by wonderful and loving people on this board!


Well, I still think you are wonderful! :hugs:


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## Andros (Aug 26, 2009)

webster2 said:


> Well, I still think you are wonderful! :hugs:


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## northernlite (Oct 28, 2010)

The half life of Levothyroxine is 3-4 days in a hyperthyroid individual, 6-7 days in a euthyroid individual and 9-10 days in a hypothyroid individual. That is why it takes so long to see the effects of a change in dosage. Although it is not exact but in a euthyroid person, it will be approximately 14 days before the levothyroxine I took this morning is gone from my body. So it take approximately 14 days after an increase before your body is working fully with that new dose. That is longer (18-20 days) when you just begin medication and are quite hypothyroid.

In luvmyboys2003 case, since she thinks she is running a bit hyper right now, hopefully she will start to feel the impact of her decrease a little sooner since the half life is shorter when you are hyper. Her body will use up (or excreet) the 100 mcg doses sooner and she will be running on the 88 mcg sooner.

That is the theory but I do believe how each person responds is a very individual thing....


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## Shiraz (Oct 19, 2009)

A medication's half-life is the time it takes for the plasma concentration of a drug to reach half of its original concentration. More simply put, the half-life of a drug is how long it takes for half of it to be eliminated from the bloodstream.

Since Synthroid (and most other thyroid pills) behave exactly as normal human thyroid hormone, they are not rapidly cleared from the body as other medications are. Most thyroid pills have a half-life of 6.7 days which means they must be stopped (or started) for five or six weeks (five or six half-lives) before accurate thyroid testing is possible. An exception to the long half life of thyroid medication is Cytomel - a thyroid pill with a half-life of only forty-eight hours.

A medication's half-life is the time it takes for the plasma concentration of a drug to reach half of its original concentration (or, how long it takes for half of it to be eliminated from the bloodstream). IOW, if the half-life of a drug is 24 hours, it would take four days to reach full concentration. So, you can see, at a 7 day half-life, why T4 medication takes so long to build up in the blood.

Also, because of the long half-life, it does not matter what time of day a person takes the T-4 medication. Since it takes one week for the first pill to reach full potency and about 6 - 8 weeks for a week of pills to reach full potency in the blood, that is the reason lab tests should not be done until a person has been on the thyroid meds for at least six weeks.

As an example, if one goes off any medication with a half-life of 7 days, here is the mathmatical sequence of how much med is left in the body.

After 7 days after the last dose, one has about 50% of that dose remaining in the body.
After 14 days after the last dose, one had about 25% of that dose remaining in the body.
After 21 days after the last dose, one had about 12.5% of that dose remaining in the body.
After 28 days after the last dose, one had about 6.25% of that dose remaining in the body.
After 35 days after the last dose, one had about 3.125% of that dose remaining in the body.
After 42 days after the last dose, one had about 1.5625% of that dose remaining in the body.
After 49 days after the last dose, one had about 0.7825% of that dose remaining in the body.
After 56 days after the last dose, one had about 0.390625% of that dose remaining in the body.

56 days is 8 weeks.

Hope this helps clear things up!!


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## northernlite (Oct 28, 2010)

Wow, impressive!! Much longer than I would have even guessed and that certainly explains the 8 weeks after medication change blood testing requirements.

So it cuts by half each 7 days in a euthyroid person so that would be shorter in a hyper person and even longer for a hypo person. This also explains to me why I saw improvemnts in myself for 9-10 weeks after a medication increase when I was more hypo.


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## webster2 (May 19, 2011)

Shiraz said:


> A medication's half-life is the time it takes for the plasma concentration of a drug to reach half of its original concentration. More simply put, the half-life of a drug is how long it takes for half of it to be eliminated from the bloodstream.
> 
> Since Synthroid (and most other thyroid pills) behave exactly as normal human thyroid hormone, they are not rapidly cleared from the body as other medications are. Most thyroid pills have a half-life of 6.7 days which means they must be stopped (or started) for five or six weeks (five or six half-lives) before accurate thyroid testing is possible. An exception to the long half life of thyroid medication is Cytomel - a thyroid pill with a half-life of only forty-eight hours.
> 
> ...


It sure did! Thanks!


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## Andros (Aug 26, 2009)

Shiraz said:


> A medication's half-life is the time it takes for the plasma concentration of a drug to reach half of its original concentration. More simply put, the half-life of a drug is how long it takes for half of it to be eliminated from the bloodstream.
> 
> Since Synthroid (and most other thyroid pills) behave exactly as normal human thyroid hormone, they are not rapidly cleared from the body as other medications are. Most thyroid pills have a half-life of 6.7 days which means they must be stopped (or started) for five or six weeks (five or six half-lives) before accurate thyroid testing is possible. An exception to the long half life of thyroid medication is Cytomel - a thyroid pill with a half-life of only forty-eight hours.
> 
> ...


What a doll you are!


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## Andros (Aug 26, 2009)

northernlite said:


> The half life of Levothyroxine is 3-4 days in a hyperthyroid individual, 6-7 days in a euthyroid individual and 9-10 days in a hypothyroid individual. That is why it takes so long to see the effects of a change in dosage. Although it is not exact but in a euthyroid person, it will be approximately 14 days before the levothyroxine I took this morning is gone from my body. So it take approximately 14 days after an increase before your body is working fully with that new dose. That is longer (18-20 days) when you just begin medication and are quite hypothyroid.
> 
> In luvmyboys2003 case, since she thinks she is running a bit hyper right now, hopefully she will start to feel the impact of her decrease a little sooner since the half life is shorter when you are hyper. Her body will use up (or excreet) the 100 mcg doses sooner and she will be running on the 88 mcg sooner.
> 
> That is the theory but I do believe how each person responds is a very individual thing....


Thank you so much for your help in this matter (and all else you contribute here); it is a complicated situation due to individual circumstance.


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