peripheral vs. general thyroid hormone resistance

[Guest guest]

I need help in making sense of the information below (from Dr.

Lowe's site). I'm trying to understand this...want to make sure you

all get out of this what I'm getting. Here's my understanding (put

very simplistically)

Peripheral tissues are include any of the tissues (other than the

pituitary) that are resistant to thyroid hormones. So since the

pituitary is getting enough hormone, then someone with this problem

would need more thyroid hormone. This suppresses TSH...it will show

in hyper range...but the peripheral tissues are not getting enough

thyroid hormone...thus peripheral resistance.

Is this how you all understand it?

My neurologist kept trying to explain to me what he felt was

happening and I could never understand it. I think I finally do. He

kept telling me he didn't think my brain cells were getting enough

thyroid hormone, and that even though my TSH showed that I was in

the hyper range, he felt I was undermedicated.

So my brain cells would be peripheral tissues.

The nurse practitioner I saw today was telling me it didn't matter

that my TSH was so low because I don't have symptoms of being over-

medicated; my symptoms are still hypo symptoms. I don't remember a

thing she said except that you can have a low TSH like mine, and it

may LOOK like hyperthyroidism, but it's not. I was foggy and just

don't remember what she said.

Questions, Comments, Opinions WANTED....Thanks, Sheila

December 1, 1997

Question: I'm confused by the term " thyroid hormone resistance, "

which you invoke at the cellular level to explain why

supraphysiologic levels of thyroid hormones are required to

alleviate symptoms in some patients. My impression is that you've

totally suppressed the TSH levels (TSH < 0.1) of your fibromyalgia

patients who've required massive doses before they've responded. Is

this true? But the explanation I see most commonly for " thyroid

hormone resistance " suggests that TSH levels are normal---see, for

example, the link (http://www.thyrolink.com/thyint/3-

96int.htm#resist) which explains that, in cases of

resistance, " administration of supraphysiologic doses of thyroid

hormone fail to suppress TSH secretion. "

Dr. Lowe: When supraphysiologic dosages of thyroid hormone fail to

suppress TSH secretion, the patient has " general " resistance to

thyroid hormone. This classification of thyroid hormone resistance

is different from the one that manifests as fibromyalgia in many

patients. The latter classification is termed " peripheral "

resistance to thyroid hormone. I will explain the difference between

general and peripheral resistance.

The classification of thyroid hormone resistance is based on whether

(1) the pituitary gland and (2) the other tissues of the body

(referred to as " peripheral " tissues) are involved in the patient's

resistance. In general resistance, both the pituitary gland and the

peripheral tissues are partially resistant to thyroid hormone. The

patient's thyroid hormone levels are elevated, but his TSH level and

his peripheral tissue metabolism are usually normal. Here's why:

In normal functioning of the hypothalamic-pituitary-thyroid axis,

when the amount of thyroid hormone in the blood reaches an

appropriate level, it then inhibits secretion of TSH by the

pituitary gland (this is a normal " feedback " mechanism). But, when

the pituitary tissue is resistant to thyroid hormone, much larger

amounts are necessary to suppress TSH secretion. When the peripheral

tissues are also partially resistant, large amounts of thyroid

hormone are needed to " override " the resistance and drive the

subnormal metabolism in the periphery to a higher, normal rate.

Typically, when these large amounts of thyroid hormone (secreted by

a thyroid gland stimulated by large amounts of TSH from a resistant

pituitary) finally increase enough to normalize the metabolic rate

of the patient's peripheral tissues, the pituitary tissue also

finally responds to this amount by reducing its secretion of TSH

into the normal range. Thus, patients with general resistance

usually have clinically normal peripheral tissue metabolism with

high levels of thyroid hormone in the blood, and a normalized level

of TSH (finally suppressed only by the high blood levels of thyroid

hormone). In this way, the circulating levels of thyroid hormone are

kept high enough to override the peripheral tissue resistance (with

normalized metabolism) and the pituitary resistance (with normalized

TSH). In other words, many general resistance patients appear

clinically normal except for the high thyroid hormone levels.

In peripheral resistance to thyroid hormone, only the peripheral

tissues are resistant. The pituitary tissue responds normally to a

normal amount of thyroid hormone in the blood, and it decreases its

TSH output when the blood levels signal that it should do so. Normal

blood levels of thyroid hormone, then, properly suppress pituitary

gland release of TSH, and keep the circulating TSH levels normal.

What's important to realize in this scenario is that the feedback

between the pituitary gland and the thyroid gland is normal, and

both glands secrete normal amounts of their respective hormones. But

the normal thyroid hormone levels are insufficient to override the

partial resistance of tissues other than the pituitary--that is the

peripheral tissues. As a result, metabolism in the peripheral

tissues is subnormal. To speed peripheral tissue metabolism up to

normal, the peripheral resistance patient must use large dosages of

thyroid hormone. But the effect of these large dosages on the

normally responsive pituitary tissue is suppression of the TSH.

Thus, secretion of TSH, and its circulating level, are extremely

low.

Unfortunately, most physicians become alarmed when they measure the

TSH level in such a patient and find it extremely low. Physicians

have been taught that a low TSH level means only one thing in a

patient taking thyroid hormone--the dosage is too high and is going

to harm the patient. It will take some years for physicians to learn

about peripheral resistance to thyroid hormone and to understand the

odd test values these patients have when taking effective dosages of

thyroid hormone. Patients with peripheral resistance must take TSH-

suppressing dosages of thyroid hormone to have normal peripheral

tissue metabolism. But there is nothing whatsoever harmful to these

patients in having their TSH suppressed by these dosages of thyroid

hormone. In fact, it would be harmful for most of them not to take

such dosages. The adverse consequences include conditions such as

fibromyalgia, chronic fatigue syndrome, and liver and cardiovascular

diseases.

Here's the link where I got this info:

http://www.drlowe.com/QandA/askdrlowe/resistnc.htm

[Guest guest]

Sheila,

It was hard slogging through this, but I thank you for posting it,

as it answers some of my long-standing questions as well. I think

your summary was good; I would just add that the other (peripheral

or end-user) tissues are unable to use part of the thyroid hormone,

so they need extra supplies in order to absorb a normal amount.

Thanks again!

> I need help in making sense of the information below (from Dr.

> Lowe's site). I'm trying to understand this...want to make sure

you

> all get out of this what I'm getting. Here's my understanding (put

> very simplistically)

>

> Peripheral tissues are include any of the tissues (other than the

> pituitary) that are resistant to thyroid hormones. So since the

> pituitary is getting enough hormone, then someone with this

problem

> would need more thyroid hormone. This suppresses TSH...it will

show

> in hyper range...but the peripheral tissues are not getting enough

> thyroid hormone...thus peripheral resistance.

>

> Is this how you all understand it?

>

> My neurologist kept trying to explain to me what he felt was

> happening and I could never understand it. I think I finally do.

He

> kept telling me he didn't think my brain cells were getting enough

> thyroid hormone, and that even though my TSH showed that I was in

> the hyper range, he felt I was undermedicated.

>

> So my brain cells would be peripheral tissues.

>

> The nurse practitioner I saw today was telling me it didn't matter

> that my TSH was so low because I don't have symptoms of being over-

> medicated; my symptoms are still hypo symptoms. I don't remember a

> thing she said except that you can have a low TSH like mine, and

it

> may LOOK like hyperthyroidism, but it's not. I was foggy and just

> don't remember what she said.

>

>

>

> Questions, Comments, Opinions WANTED....Thanks, Sheila

>

> December 1, 1997

>

> Question: I'm confused by the term " thyroid hormone resistance, "

> which you invoke at the cellular level to explain why

> supraphysiologic levels of thyroid hormones are required to

> alleviate symptoms in some patients. My impression is that you've

> totally suppressed the TSH levels (TSH < 0.1) of your fibromyalgia

> patients who've required massive doses before they've responded.

Is

> this true? But the explanation I see most commonly for " thyroid

> hormone resistance " suggests that TSH levels are normal---see, for

> example, the link (http://www.thyrolink.com/thyint/3-

> 96int.htm#resist) which explains that, in cases of

> resistance, " administration of supraphysiologic doses of thyroid

> hormone fail to suppress TSH secretion. "

>

> Dr. Lowe: When supraphysiologic dosages of thyroid hormone fail to

> suppress TSH secretion, the patient has " general " resistance to

> thyroid hormone. This classification of thyroid hormone resistance

> is different from the one that manifests as fibromyalgia in many

> patients. The latter classification is termed " peripheral "

> resistance to thyroid hormone. I will explain the difference

between

> general and peripheral resistance.

>

> The classification of thyroid hormone resistance is based on

whether

> (1) the pituitary gland and (2) the other tissues of the body

> (referred to as " peripheral " tissues) are involved in the

patient's

> resistance. In general resistance, both the pituitary gland and

the

> peripheral tissues are partially resistant to thyroid hormone. The

> patient's thyroid hormone levels are elevated, but his TSH level

and

> his peripheral tissue metabolism are usually normal. Here's why:

>

> In normal functioning of the hypothalamic-pituitary-thyroid axis,

> when the amount of thyroid hormone in the blood reaches an

> appropriate level, it then inhibits secretion of TSH by the

> pituitary gland (this is a normal " feedback " mechanism). But, when

> the pituitary tissue is resistant to thyroid hormone, much larger

> amounts are necessary to suppress TSH secretion. When the

peripheral

> tissues are also partially resistant, large amounts of thyroid

> hormone are needed to " override " the resistance and drive the

> subnormal metabolism in the periphery to a higher, normal rate.

> Typically, when these large amounts of thyroid hormone (secreted

by

> a thyroid gland stimulated by large amounts of TSH from a

resistant

> pituitary) finally increase enough to normalize the metabolic rate

> of the patient's peripheral tissues, the pituitary tissue also

> finally responds to this amount by reducing its secretion of TSH

> into the normal range. Thus, patients with general resistance

> usually have clinically normal peripheral tissue metabolism with

> high levels of thyroid hormone in the blood, and a normalized

level

> of TSH (finally suppressed only by the high blood levels of

thyroid

> hormone). In this way, the circulating levels of thyroid hormone

are

> kept high enough to override the peripheral tissue resistance

(with

> normalized metabolism) and the pituitary resistance (with

normalized

> TSH). In other words, many general resistance patients appear

> clinically normal except for the high thyroid hormone levels.

>

> In peripheral resistance to thyroid hormone, only the peripheral

> tissues are resistant. The pituitary tissue responds normally to a

> normal amount of thyroid hormone in the blood, and it decreases

its

> TSH output when the blood levels signal that it should do so.

Normal

> blood levels of thyroid hormone, then, properly suppress pituitary

> gland release of TSH, and keep the circulating TSH levels normal.

> What's important to realize in this scenario is that the feedback

> between the pituitary gland and the thyroid gland is normal, and

> both glands secrete normal amounts of their respective hormones.

But

> the normal thyroid hormone levels are insufficient to override the

> partial resistance of tissues other than the pituitary--that is

the

> peripheral tissues. As a result, metabolism in the peripheral

> tissues is subnormal. To speed peripheral tissue metabolism up to

> normal, the peripheral resistance patient must use large dosages

of

> thyroid hormone. But the effect of these large dosages on the

> normally responsive pituitary tissue is suppression of the TSH.

> Thus, secretion of TSH, and its circulating level, are extremely

> low.

>

> Unfortunately, most physicians become alarmed when they measure

the

> TSH level in such a patient and find it extremely low. Physicians

> have been taught that a low TSH level means only one thing in a

> patient taking thyroid hormone--the dosage is too high and is

going

> to harm the patient. It will take some years for physicians to

learn

> about peripheral resistance to thyroid hormone and to understand

the

> odd test values these patients have when taking effective dosages

of

> thyroid hormone. Patients with peripheral resistance must take TSH-

> suppressing dosages of thyroid hormone to have normal peripheral

> tissue metabolism. But there is nothing whatsoever harmful to

these

> patients in having their TSH suppressed by these dosages of

thyroid

> hormone. In fact, it would be harmful for most of them not to take

> such dosages. The adverse consequences include conditions such as

> fibromyalgia, chronic fatigue syndrome, and liver and

cardiovascular

> diseases.

>

>

> Here's the link where I got this info:

>

> http://www.drlowe.com/QandA/askdrlowe/resistnc.htm

[Guest guest]

Yes, anywhere the thyroid hormone is distributed to to run the functions of

the human body is peripheral tissues. I do not believe in counting in the

worth of the TSH because of these issues like this. So what if the thyroid

isn't being stimulated by the pituitary, as long as the person's tissues

aren't being oversaturated by T3-T4 (after all, that's the ONLY important

issue with 0'ed out TSH). To me, the importance of the TSH only comes into

play if it is high and OVERstimulating the thyroid itself, which is common

with autoimmune antibodies. If they are attacking at the level of the TSH

receptors directly ON the thyroid, the pituiatary is NOT getting the signal

that the thyroid is actually producing enough thyroid hormone. I'm

wondering if you don't have BOTH problems though, i.e., autoantibody

receptor problems AND not making enough thyroid hormone. You are obviously

NOT HYPERthyroid, and I think this is exactly what the nurse was trying to

explain. I'm thinking that you said that your diagnosis is Hashi's, right?

I believe that in some persons, these antibodies can attack for yrs and yrs,

even though most of the thyroid tissue may be already destroyed before that.

Because of this, I would say that you need both---a T4 med AND the Armour.

However, didn't you say that you just now started taking the Armour? If

you're low in T4, Armour will hardly ever have enough T4 to make up the

difference there, but is excellent for the T3, T1, T2, and calcitonin. I

take, at this time, 50 mcgs of Eutirox (Levoxyl) with 45 mgs of Armour.

I've been playing with these dosages for awhile now, trying to get the right

combo. I will retest next month to see about the levels, but the main thing

is going to be the way I FEEL, rather than the levels with Hashi's. As long

as that TSH level is way down from where it was at 35 something. Constant

stimulation of TSH of the thyroid is known to make a higher thyroid cancer

risk.

Texas

peripheral vs. general thyroid hormone resistance

> I need help in making sense of the information below (from Dr.

> Lowe's site). I'm trying to understand this...want to make sure you

> all get out of this what I'm getting. Here's my understanding (put

> very simplistically)

>

> Peripheral tissues are include any of the tissues (other than the

> pituitary) that are resistant to thyroid hormones. So since the

> pituitary is getting enough hormone, then someone with this problem

> would need more thyroid hormone. This suppresses TSH...it will show

> in hyper range...but the peripheral tissues are not getting enough

> thyroid hormone...thus peripheral resistance.

>

> Is this how you all understand it?

>

> My neurologist kept trying to explain to me what he felt was

> happening and I could never understand it. I think I finally do. He

> kept telling me he didn't think my brain cells were getting enough

> thyroid hormone, and that even though my TSH showed that I was in

> the hyper range, he felt I was undermedicated.

>

> So my brain cells would be peripheral tissues.

>

> The nurse practitioner I saw today was telling me it didn't matter

> that my TSH was so low because I don't have symptoms of being over-

> medicated; my symptoms are still hypo symptoms. I don't remember a

> thing she said except that you can have a low TSH like mine, and it

> may LOOK like hyperthyroidism, but it's not. I was foggy and just

> don't remember what she said.