>From: THYROID automatic digest system <[log in to unmask]>

>From:    Holly Jagger <[log in to unmask]>
>Subject:
>
>List members,
>Was just told that my thyroid binding globulins are low.

http://www.nlm.nih.gov/medlineplus/ency/article/003688.htm

The thyroid hormones T3 and T4 are transported in the body via proteins that 
bind them. Only free (unbound) T3 and T4 are active in the body. Measuring 
T3 uptake (the RT3U test) helps estimate the availability of thyroxin 
binding globulin (TBG) -- the protein that carries most of the T3 and T4 in 
the blood. RT3U is inversely proportional to TBG levels: that is, if the TBG 
level goes up, the RT3U values will go down. A higher RT3U value means less 
TBG is available, possibly as a result of hyperthyroidism.

Lower-than-normal levels may indicate:

    * acute hepatitis
    * hypothyroidism
    * hypothyroidism; primary
    * hypothyroidism; secondary
    * pregnancy
    * estrogen administration
***********************

Excessive corticosteroids can cause lowTBG.

Every time I was sick, my doctor would say it could be because "you're on 
hydrocortisone. It lowers the immune system."  One day, when I walked out of 
the office, after the doctor had said that, the receptionist for some reason 
showed me on the schedule everybody else coming in that day were also there 
for mono rechecks, after having had the test done.   So, I was truly sick, I 
didn't have mono, but apparently a lot of other patients were having the 
same problems I was, yet he blamed the Cortef.  Physiological doses of 
hydrocortisone get a lot of blame they shouldn't.

Besides you're taking dosages normal to your body, not excessive amounts.

The other thing is, I think doctors diagnose that based on the thyroid 
uptake test (RT3U)  The uptake has an inverse relationship to TBG.  Doctors 
sometimes forget it's an inverse relationship and read it backwards.

Supposedly, when thyroid hormones are bound in TBG, they are not active 
anyway.  Which is why doctors measure the free hormones.

Endo says, that
>could be because I take steroids for Addison's Disease.
>
>Some questions I have--
>How do steroids, replacement level or thereabouts, affect TBG?
>Does low TBG indicate usually a need for a little T3 replacement as well as
>the T4?
>
>I also have low SHBG.  How do TBG and sex hormone binding globulin 
>interact,
>if they do?

http://www.digitalnaturopath.com/cond/C655233.html
Estrogens increase liver manufacture of SHBG. Androgens decrease it. A lack 
of estrogens can effectively increase available blood androgens.

Modest reductions in SHBG levels may be encountered in individuals with 
hypothyroidism.
Modest reductions in SHBG levels may be encountered in individuals with 
hyperprolactinemia
Modest reductions in SHBG levels may be encountered in individuals with 
Cushing's syndrome.
SHBG levels respond to extreme changes in body weight, decreasing in obese 
patients.
Low levels are often found in cases of polycystic ovary syndrome. SHBG is 
low in about 50% of cases.
Modest reductions in SHBG levels may be encountered in individuals receiving 
glucocorticoids such as prednisone.
Research has discovered that sex hormone binding globulin (SHBG), a 
relatively unknown blood protein, is a reasonably good indicator of insulin 
resistance. Low levels of SHBG are consistently linked to high levels of 
insulin in the body. Sustained high levels of insulin are, in turn, 
associated with the development of the chronic diseases such as high blood 
pressure, diabetes and coronary heart disease.
*********

Skipper

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