Aa
If this is true... why wouldn't everyone do it?
Chitchat's question about missing a dose of meds sparked my memory and I thought I'd share this conversation with you and see what you think of it:
When I went to the teaching hospital 2 weeks ago for a follow up, the dr was talking to the intern and explaining everything in great detail (it was really great for me too!). He was explaining about how the body converts T4 to T3 as needed, and how incredible the T4 drugs are, etc. Anyway... he was talking about how T4 stores up in the body and so if you miss a dose, it's no big deal... and he said that SOME people actually will take 7 pills one time a week simply b/c they hate taking pills, or forget every day, so this makes it easier. And he said, "It works just fine!"
SO... if that's true... why don't we all administer our drugs this way, and why wouldn't the Mfgr make pills in the higher concnetrations to accomodate that kind of administration?
Also... it seems to me that the body could only store up so much T4... that after a while, wouldn't it just expell the extra? Of can it store up as much T4 as you put in it?
I am not considering doing this since this is not my primary endo, nor did he suggest it... he just relayed a story and now I'm curious. It would be really nice to take a pill once a week rather than every day, but there's got to be a reason why this is not a widely practiced administration of thyroid replacement.
When I went to the teaching hospital 2 weeks ago for a follow up, the dr was talking to the intern and explaining everything in great detail (it was really great for me too!). He was explaining about how the body converts T4 to T3 as needed, and how incredible the T4 drugs are, etc. Anyway... he was talking about how T4 stores up in the body and so if you miss a dose, it's no big deal... and he said that SOME people actually will take 7 pills one time a week simply b/c they hate taking pills, or forget every day, so this makes it easier. And he said, "It works just fine!"
SO... if that's true... why don't we all administer our drugs this way, and why wouldn't the Mfgr make pills in the higher concnetrations to accomodate that kind of administration?
Also... it seems to me that the body could only store up so much T4... that after a while, wouldn't it just expell the extra? Of can it store up as much T4 as you put in it?
I am not considering doing this since this is not my primary endo, nor did he suggest it... he just relayed a story and now I'm curious. It would be really nice to take a pill once a week rather than every day, but there's got to be a reason why this is not a widely practiced administration of thyroid replacement.
Great Info .. thanks so much for taking the time to gather this info for us! I started my 100mcgs this morning .. I had two 50mcgs leftover in a bottle LOL so that worked out well..........................If I stop to think about all this it truly amazes me to be on 100mcgs bcz they thoy thought "if" cancer was found I'd only be on 25-50mcgs at the most but other side is <> functioning. So be it .. at least they have these meds available for us thyroidless people of dysfunctional thyroid people!!!
C~
C~
A pharmacist told me about a trial they did here (Australia) for thyroid patients taking a weekly dose - but obviously it was not implemented, he didn't know why? But I believe that the weekly dosage was calculated by multiplying the daily dose by 7 and adding a set amount to allow for degredation over time (I think)?
The reason why weekly treatment regimes are possible is because thyroxine is such a slow acting drug - the peak effect of the thyroxine I took today will not be realised for 3 or 4 weeks (or more). This same reason is why we can also use altnernate day dosing (sometimes called intermediate dosing) for fine tuning dose adjustments. Eg. I take 150mcg for 5 days of the week and 100 mcg for 2 days of the week and get an average dosage of approx. 136mcg per day (different dose strengths available in Australia).
My guess (and I'm sure there are probably other reasons too???) is that we don't all do this weekly dosing because it is not the 'optimal' treatment regime - 'optimal' would have to be a close replication of 'normal' thyroid function/regulation. Our TSH feedback cycle (when you have an intact fully functioning thyroid) is constantly working back and forth to keep levels in check in a consistent manner (involves hypothalamus, pituitary gland and thyroid gland). The thyroid doesn't naturally give one big release once a week obviously. BUT there are exceptions when a person getting replacement hormone in a single weekly dose may be preferable as discussed - for example; the person who forgets their pills frequently will likely suffer hypothyroidism and the associated symptoms (people who are continuoulsy non-compliant or suffer dementia/alzheimers or other neurological deficits).
Here's a excerpt from Synthroid's Prescribing Info (See below this paragraph) which explains exactly how the T4 is absorbed in the small intestine, passes into the circulation and is distributed (or stored) bound to proteins in the blood, how it is metabolised (broken down) and excreted.
http://www.rxabbott.com/pdf/Synthroid.pdf
"Pharmacokinetics
ABSORPTION - Absorbtion of orally administered T4 from the gastrointestinal (GI) tract ranges from 40% - 80%. The majority of the levothyroxine dose is absorbed from the jejunum and upper ileum. The relative bioavailability of Synthroid tablets, compared to an equal nominal dose of oral levothyroxine sodium solution, is approximately 93%. T4 absorbtion is increased by fasting and decreased in malabsorbtion syndromes and by certain foods such as soybean infant formula. Dietary fiber decreases bioavailability of T4. Absorbtion may also decrease with age. In addition many drugs and foods affect T4 absorbtion (see PRECAUTIONS, Drug Interactions & Drug-Food Interactions)
DISTRIBUTION - Circulating thyroid hormones are greater than 99% bound to plasma proteins, including thyroxine-binding globulin (TBG), thyroxine binding prealbumin (TBPA), and albumin (TBA), whose capacities and affinities vary for each hormone. The higher affinity of both TBG and TBPA for T4 partially explains the higher serum levels, slower metabolic clearance and longer half life of T4 compared to T3. Protein bound thyroid hormones exist in reverse equillibrium with small amounts of free hormone. Only unbound hormone is metabolically active. Many drugs and physiologic conditions affect the binding of thyroid hormones to serum proteins (see PRECAUTIONS, Drug Interactions, and Drug-Laboratory Test Interactions). Thyroid hormones do not readily cross the placental barrier (see PRECAUTIONS, Pregnancy).
METABOLISM - T4 is slowly eliminated (see Table 1). The major pathway of thyroid hormone metabolism is through sequential deiodination. Approximately 80% of circulating T3 is derived from peripheral T4 by monodeiodination. The liver is the major site of degredation for both T4 and T3, with T4 deiodination occuring at a number of additional sites, including the kidneys and other tissues. Approximately 80% of the daily dose of T4 is deiodinated to yield equal amounts of T3 and reverse T3 (rT3). T3 and rT3 are further deiodinated to diiodothyronine. Thyroid hormones are also metabolised via conjugation with glucuronides and sulfates and excreted directly into the bile and gut where they undergo enterohepatic recirculation.
EXCRETION - Thyroid hormones are primarily eliminated by the kidneys. A portion of conjugated hormone reaches the colon unchanged and is eliminated in the feces. Approximately 20% of T4 is eliminated in the stool. Urinary excretion of T4 decreases with age."
***END EXCERPT***
diiodothyronine is also referred to as T2.
The Australian prescribing info for Oroxine/Eutroxsig *equivalent synthetic T4 brand (from MIMS) also says;
"Excretion. Thyroxine sodium has a plasma half-life in euthyroidism of about six to seven days. In hypothyroidism, the half-life is prolonged between nine to ten days. However, the half-life is reduced between three to four days in hyperthyroidism."
^^^A half life is how long it takes for a substance to decrease to half the strength you began with (once the substance is stopped).
For Rhonda/dart frog
In summary; the liver does not 'store' thyroxine although it is involved in breaking it down - thyroxine is stored bound (or stuck to) proteins found in the plasma portion of your blood.
For everyone relying on thyroid replacement - take good care of your liver!!! Not too much alcohol (everything in moderation)!!!
Hope you are all well
~Jen
The reason why weekly treatment regimes are possible is because thyroxine is such a slow acting drug - the peak effect of the thyroxine I took today will not be realised for 3 or 4 weeks (or more). This same reason is why we can also use altnernate day dosing (sometimes called intermediate dosing) for fine tuning dose adjustments. Eg. I take 150mcg for 5 days of the week and 100 mcg for 2 days of the week and get an average dosage of approx. 136mcg per day (different dose strengths available in Australia).
My guess (and I'm sure there are probably other reasons too???) is that we don't all do this weekly dosing because it is not the 'optimal' treatment regime - 'optimal' would have to be a close replication of 'normal' thyroid function/regulation. Our TSH feedback cycle (when you have an intact fully functioning thyroid) is constantly working back and forth to keep levels in check in a consistent manner (involves hypothalamus, pituitary gland and thyroid gland). The thyroid doesn't naturally give one big release once a week obviously. BUT there are exceptions when a person getting replacement hormone in a single weekly dose may be preferable as discussed - for example; the person who forgets their pills frequently will likely suffer hypothyroidism and the associated symptoms (people who are continuoulsy non-compliant or suffer dementia/alzheimers or other neurological deficits).
Here's a excerpt from Synthroid's Prescribing Info (See below this paragraph) which explains exactly how the T4 is absorbed in the small intestine, passes into the circulation and is distributed (or stored) bound to proteins in the blood, how it is metabolised (broken down) and excreted.
http://www.rxabbott.com/pdf/Synthroid.pdf
"Pharmacokinetics
ABSORPTION - Absorbtion of orally administered T4 from the gastrointestinal (GI) tract ranges from 40% - 80%. The majority of the levothyroxine dose is absorbed from the jejunum and upper ileum. The relative bioavailability of Synthroid tablets, compared to an equal nominal dose of oral levothyroxine sodium solution, is approximately 93%. T4 absorbtion is increased by fasting and decreased in malabsorbtion syndromes and by certain foods such as soybean infant formula. Dietary fiber decreases bioavailability of T4. Absorbtion may also decrease with age. In addition many drugs and foods affect T4 absorbtion (see PRECAUTIONS, Drug Interactions & Drug-Food Interactions)
DISTRIBUTION - Circulating thyroid hormones are greater than 99% bound to plasma proteins, including thyroxine-binding globulin (TBG), thyroxine binding prealbumin (TBPA), and albumin (TBA), whose capacities and affinities vary for each hormone. The higher affinity of both TBG and TBPA for T4 partially explains the higher serum levels, slower metabolic clearance and longer half life of T4 compared to T3. Protein bound thyroid hormones exist in reverse equillibrium with small amounts of free hormone. Only unbound hormone is metabolically active. Many drugs and physiologic conditions affect the binding of thyroid hormones to serum proteins (see PRECAUTIONS, Drug Interactions, and Drug-Laboratory Test Interactions). Thyroid hormones do not readily cross the placental barrier (see PRECAUTIONS, Pregnancy).
METABOLISM - T4 is slowly eliminated (see Table 1). The major pathway of thyroid hormone metabolism is through sequential deiodination. Approximately 80% of circulating T3 is derived from peripheral T4 by monodeiodination. The liver is the major site of degredation for both T4 and T3, with T4 deiodination occuring at a number of additional sites, including the kidneys and other tissues. Approximately 80% of the daily dose of T4 is deiodinated to yield equal amounts of T3 and reverse T3 (rT3). T3 and rT3 are further deiodinated to diiodothyronine. Thyroid hormones are also metabolised via conjugation with glucuronides and sulfates and excreted directly into the bile and gut where they undergo enterohepatic recirculation.
EXCRETION - Thyroid hormones are primarily eliminated by the kidneys. A portion of conjugated hormone reaches the colon unchanged and is eliminated in the feces. Approximately 20% of T4 is eliminated in the stool. Urinary excretion of T4 decreases with age."
***END EXCERPT***
diiodothyronine is also referred to as T2.
The Australian prescribing info for Oroxine/Eutroxsig *equivalent synthetic T4 brand (from MIMS) also says;
"Excretion. Thyroxine sodium has a plasma half-life in euthyroidism of about six to seven days. In hypothyroidism, the half-life is prolonged between nine to ten days. However, the half-life is reduced between three to four days in hyperthyroidism."
^^^A half life is how long it takes for a substance to decrease to half the strength you began with (once the substance is stopped).
For Rhonda/dart frog
In summary; the liver does not 'store' thyroxine although it is involved in breaking it down - thyroxine is stored bound (or stuck to) proteins found in the plasma portion of your blood.
For everyone relying on thyroid replacement - take good care of your liver!!! Not too much alcohol (everything in moderation)!!!
Hope you are all well
~Jen
Good question... I know the liver helps convert it to T3 when needed, but don't know where it's stored when you don't have a thyroid. This is one where Jenipeni will probably be very helpful.
so.....these types of drugs must not be stored in the liver...right? becuase you'd think taking a weeks worth at one time would do a number on the liver.....hm....anybody know where it does get stored at??? just wondering.
My son takes a lot of powerful medications where we have to have levels done every 4 months...have been doing this for 8 years now. The reason is we have to make sure that his liver is storing/using the drugs and not damaging the liver at all......hm....
Rhonda
My son takes a lot of powerful medications where we have to have levels done every 4 months...have been doing this for 8 years now. The reason is we have to make sure that his liver is storing/using the drugs and not damaging the liver at all......hm....
Rhonda
I have read that this once a week high dose does work fine for some people, and even though I gave very careful advice previously, my own endocrinologist(Hopkins Grad) told me if I miss a dose just take two the next day LOLOLOLOL
DON'T DO THIS. The prescribing info says not to, but I do trust my own doc in my case.
DON'T DO THIS. The prescribing info says not to, but I do trust my own doc in my case.
It may be true .. I was just thinking that some people on this board take one mcg and then alternate or on weekends take a higher dose and their docs say it all evens out in the end ????
C~
C~
My friend just had her levels drawn and the labs showed very hyper levels and her Endo asked her 3 times if she may have taken a double dose that morning? So that makes me wonder. Also, after my partial I was ok in TSH levels for 2 weeks so that goes to prove there are "stores" but then it went askew after the stores were depleted and the other side not working after the surgery *happens in 30%of the surgeries according to Dr. Lupo on other site*.
Wonder what responses you'll get ...
C~
Wonder what responses you'll get ...
C~
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