SHBG Explained as per Dr Romeo no

[Guest guest]

Further to the flurry of recent posts on SHBG I am reproducing this excellent

post. have a read.

________________________________________________________________

SHBG by Dr no

http://www.definitivemind.com/forums/showthread.php?t=86

I generally want to maintain SHBG (sex-hormone Binding Globulin) since it

prolongs the duration of action of Testosterone.

MOST OF THE TIME, I FIND SHBG TOO LOW RATHER THAN TOO HIGH.

TESTOSTERONE, itself, will drive SHBG down.

ESTROGEN will increase SHBG. Thus controlling Estradiol will lower SHBG.

INSULIN also will drive SHBG down. Insulin has the STRONGEST effect on SHBG,

compared to any other factor.

Low SHBG is a good sign that a person has Insulin Resistance or Diabetes - which

lowers Testosterone production. Insulin Resistance or Diabetes greatly increases

the risk for Cardiovascular disease

Realize that SHBG is determined by multiple hormones: Estrogen, Progesterone,

Thyroid Hormone, Testosterone, DHEA, Growth Hormone, Insulin, etc.

Thus, whatever SHBG one has (outside of a low level, for which problems with

Insulin need to be assessed) does not tell if something is wrong since the

effects of these hormones may cancel each other out.

Thus, a specific SHBG, outside of diabetes, does not tell much about what is

happening with a person.

I GENERALLY DO NOT LIKE DRIVING SHBG TOO LOW SINCE TESTOSTERONE AND ESTROGEN

WON'T LAST LONG IN THE BODY.

The lower the SHB, the more likely Testosterone level is going to be low since

FREE TESTOSTERONE HAS A HALF-LIFE OF ONLY 10 TO 100 MINUTES.

Without SHBG, nearly all Testosterone (unless it is continuously produced) would

be gone from the body in less than about 50 minutes to 8 hours, being destroyed

by degradative enzymes, such as by those in the Liver.

SHBG MAKES TESTOSTERONE LAST LONGER.

The higher the SHBG, the lower the dose of Testosterone is needed in treatment.

INSULIN, BY REDUCING SHBG, CONTRIBUTES TO HYPOGONADISM IN DIABETES.

There is actually a study saying that Thyroid Hormone T-3 mainly can cause an

increase in SHBG over time.

The higher the SHBG, the longer Testosterone functions in the body.

The lower the SHBG, the shorter Testosterone functions in the body.

This applies to Estradiol also.

The lower the SHBG the more frequently Testosterone HRT dosing needs to be done

to maintain a given Testosterone level. The lower the SHBG, the more

rollercoaster a person's experience with Testosterone HRT.

Let's look at what influences SHBG:

Increases SHBG:

Estrogens (particularly Estradiol)

Progesterone (by increasing Estrogen receptors)

Thyroid Hormone (particularly Hyperthyroidism)

Liver Disease

Anorexia, Starvation

Hypoglycemia (low Insulin)

Reduces SHBG:

Insulin (and insulin resistance)

Testosterone

Growth Hormone

DHEA

Other Androgens

Obesity

Hypothyroidism

Excessive Cortisol (Cushing's Syndrome or Disease)

Progestins i.e. synthetic non bio-identical progesterone (by blocking

Progesterone's effects)

Excessively high SHBG may indicate factors increasing SHBG may be in excess in

thus should be addressed. For example, an excess of Estrogen to Testosterone may

result in high SHBG.

Since SHBG is determined by several hormones, it is not generally a good

component to address directly. Rather the influences affecting SHBG should be

addressed independently of SHBG.

Testosterone replacement alone will drive down SHBG. Low SHBG, high Free

Testosterone but LOW total Testosterone is common in Diabetes.

From my point of view, overly focusing on SHBG when trying to improve LIBIDO

once Total Testosterone is raised to at least 650 ng/dL is a fairly narrow point

of view. Free Testosterone is only a fraction of Testosterone signalling. Free

Testosterone too often does NOT determine libido. One can use Bioavailable

Testosterone as a measure of Testosterone's signalling strength.

I, myself, consider TOTAL Testosterone more important. Testosterone which isn't

free - but is bound to SHBG - also has a signalling function on SHBG receptors.

To take this function into account, I use Total Testosterone as a clearer

measure of Testosterone signalling.

If one focuses on the factors that determine SHBG and focus on optimizing them

or treating the disease condition involved, then one hardly needs to measure

SHBG at all.

HIGH or LOW SHBG indicates something is wrong but does not tell you WHAT is

wrong. Thus, ALONE, it is not a useful measure. SHBG WITHIN the reference range

also doesn't tell if something is wrong. Factors that influence SHBG can cancel

each other out, thus SHBG will be in the reference range. Thus, one still has to

optimize each factor that influences SHBG separately.

As a result of these considerations, SHBG is a minor player. I would look at the

other issues that influence SHBG instead, in their own right, as more important

considerations.

When Total Testosterone is high but libido is low, then the problem is other

than Testosterone, and unlikely to be SHGB.

I would look at the rest of the system (e.g. Estrogen, Adrenal Function,

Thyroid, nervous system function, Dopamine, Insulin, nutrition, etc.) for causes

of low libido.

_______________________________________________________________

Lethal Lee