The Politics of Thyroid
Apr. 27th, 2009 10:42 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
deirdreOnce upon a time, starting in the 1890s, hypothyroid issues were treated by symptom and were treated with the addition of dessicated animal thyroid, which includes T1, T2, T3, T4, and calcitonin (yes, related to calcium and risk of osteoporosis), the five main thyroid hormones.
In the 1950s, synthetic thyroid, specifically synthetic T4, came onto the market and essentially replaced the dessicated animal hormone. Now this was great for people who needed T4 primarily (in a normal thyroid, T4 can convert to T3) or who couldn't tolerate the animal form, but it didn't work so well for people who had problems converting T4 to T3.
If you look at the big biochemistry processes, sometimes I'm amazed we work at all, because there's so many steps that have to work, and the thyroid is no exception. So measuring one thing (TSH, a pituitary hormone) or two things (TSH and Free T4) doesn't really give an adequate picture of thyroid function, especially when a number not within the 5 sigma umbrella is considered "normal."
Here's a population study graph of 13,000 people:
Given that, does 3.08 look like a normal number to you?
The AACE's current recommendation is a TSH of 4.5. In that page, they're saying they reverse their position of 3.0. They consider a TSH of 4.5 subclinical and add, "The paper states that since available data do not convincingly show clear-cut benefit from early thyroxine therapy, routine T4 treatment for patients with TSH between 4.5 and 10 mIU/L is not warranted."
In 2002, AACE encouraged doctors to "consider treatment" if the TSH fell outside the range of 0.3 to 3.0.
In their 2006 guideline PDF, it states that, "[subclinical hypothyroidism] is a common disorder, the prevalence ranging from 1 to 10% of the adult population with increasing frequency in women."
Perhaps the single most useful thing I've found is the chart on page 1 of The AACE's 2006 conference notes, which has a chart of TSH distribution. You can see from that that, in a sample of 13,000+ individuals, approximately 5% of the sample had TSH higher than 2.0, and 1% above 3.0. The biggest clump is around 1.0, likely where the mean is.
In the 1950s, synthetic thyroid, specifically synthetic T4, came onto the market and essentially replaced the dessicated animal hormone. Now this was great for people who needed T4 primarily (in a normal thyroid, T4 can convert to T3) or who couldn't tolerate the animal form, but it didn't work so well for people who had problems converting T4 to T3.
If you look at the big biochemistry processes, sometimes I'm amazed we work at all, because there's so many steps that have to work, and the thyroid is no exception. So measuring one thing (TSH, a pituitary hormone) or two things (TSH and Free T4) doesn't really give an adequate picture of thyroid function, especially when a number not within the 5 sigma umbrella is considered "normal."
Here's a population study graph of 13,000 people:
Given that, does 3.08 look like a normal number to you?
The AACE's current recommendation is a TSH of 4.5. In that page, they're saying they reverse their position of 3.0. They consider a TSH of 4.5 subclinical and add, "The paper states that since available data do not convincingly show clear-cut benefit from early thyroxine therapy, routine T4 treatment for patients with TSH between 4.5 and 10 mIU/L is not warranted."
In 2002, AACE encouraged doctors to "consider treatment" if the TSH fell outside the range of 0.3 to 3.0.
In their 2006 guideline PDF, it states that, "[subclinical hypothyroidism] is a common disorder, the prevalence ranging from 1 to 10% of the adult population with increasing frequency in women."
Perhaps the single most useful thing I've found is the chart on page 1 of The AACE's 2006 conference notes, which has a chart of TSH distribution. You can see from that that, in a sample of 13,000+ individuals, approximately 5% of the sample had TSH higher than 2.0, and 1% above 3.0. The biggest clump is around 1.0, likely where the mean is.