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What is the mechanism of action of androgens on growth in children?

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Hello i understand androgens play a role in pubertal growth, and also in pre pubertal growth as evidence of sexual differences in growth during childhood. My question is: what is the mechanism of action of androgens on growth in children....is it via effect on growth hormone axis OR via direct action at the plates? Or maybe even both? Thanks and Regards
Posted Mon, 23 Sep 2013 in Thyroid Problem and Hormonal Problems
 
 
Answered by Dr. Jose Ignacio Artero Munoz 1 hour later
Brief Answer:
Androgens

Detailed Answer:
Hello,

Delighted to be able to help.

The effect of androgens on the growth is acting on growth hormone in an indirect way. Androgens are converted to estrogens in peripheral fat, a low level of androgens causes a lower conversion and lower estrogens levels. The lower level of estrogens can cause lower levels of growth hormone although growth hormone levels depend on many other hormonal and nonhormonal factors (exercise, chronic intake of corticosteroids ...). Consequently the effect of androgen levels on growth is not as important as its function in the development of male sexual characteristics.

A child with low levels of androgens major signs will be lack of testicular development, decreased muscle mass, decreased body hair, decreased tone of voice ....the growth retardation is not the main symptom.

I Hope I have answered your query. If you have any further questions I will be happy to help.
If you do not have any clarifications, please don’t forget to evaluate my answer.

I wish you good health
Above answer was peer-reviewed by
 
Follow-up: What is the mechanism of action of androgens on growth in children? 1 hour later
hi and thanks for your answer.

i read some studies suggesting a direct effect of androgen on bone growth , before conversion to estrogen.....This study says oxandrolone, a non-aromatizable androgen, caused growth in growth retarded children. GH levels were unchanged.

so how do you explain the growth in this case?

Best Regards
 
 
Answered by Dr. Jose Ignacio Artero Munoz 3 hours later
Brief Answer:
Oxandrolone

Detailed Answer:
Hello.Delighted to be able to help.

It is true that oxandrolone causes growth in children with growth retarded by direct action on the plate.Since the 70s has been used for this purpose but tell you about:

1.-Although oxandrolone is chemically an androgen, androgenic effects are very weak compared with testosterone.An example is that oxandrolone is used by bodybuilders to gain muscle mass without androgenic or estrogenic side effects.

2.-The main indication of Oxandrolone is the gain of muscle mass in people with prolonged bed after surgical intervention.

3.-Its use as a growth promoter has been limited by its significant side effects, especially at liver.


I Hope I have answered your query.If you do not have any clarifications, you can close the discussion and , please ,don’t forget to evaluate my answer.

I wish you good health
Above answer was peer-reviewed by
 
Follow-up: What is the mechanism of action of androgens on growth in children? 1 hour later
Thank you for answer.

I understand after birth, androgens are also present. Do they also partly promote growth via action at plate during a baby's growth?

I understand androgen presence is important in boys childhood growth.....

 
 
Answered by Dr. Jose Ignacio Artero Munoz 1 hour later
Brief Answer:
Yes, but through an indirect effect

Detailed Answer:
Hello,

As you say, androgens are also present after birth.

The effect of androgens on the growth is indirect through its conversion to estrogens. Estrogens increase GH levels. GH acts on the growth plate.

Besides estrogens increase bone density(In menopause, when estrogen levels decreasing suddenly, appears osteoporosis)

It is important androgen levels during the child's growth but is more important right level of GH and other substances such as somatomedins.

I Hope I have answered your query.If you do not have any clarifications, you can close the discussion and , please ,don’t forget to evaluate my answer.

I wish you good health.

Regards,
Above answer was peer-reviewed by
 
Follow-up: What is the mechanism of action of androgens on growth in children? 11 hours later
Thank you for answer.

My question: Does the androgen help with direct bone growth, prior to conversion?

Oxandrolone , which doesn't convert, has been shown to promote growth.....therefore some growth must be attributed to the androgen itself??

 
 
Answered by Dr. Jose Ignacio Artero Munoz 49 minutes later
Brief Answer:
Androgens

Detailed Answer:
Hello.Delighted to be able to help.
Direct action, before the conversion, of androgens on the growth plate is not proven.Oxandrolone have direct action on the growth plate but, as I said, its androgenics effects are very weak,is not considered an androgen.
I wish you good health.
Above answer was peer-reviewed by
 
Follow-up: What is the mechanism of action of androgens on growth in children? 2 days later
Thank you Dr Munoz.

One final question.

In boys, first sign of puberty is characterized by increase in testicular size. I understand the increase in gonadotropins is responsible for this. DO BOTH GONADOTROPINS (LH + FSH) RISE TOGETHER AT START OF PUBERTY, OR INDEPENDANTLY OF EACH OTHER ?

Best Regards
 
 
Answered by Dr. Jose Ignacio Artero Munoz 3 hours later
Brief Answer:
Gonadotropins

Detailed Answer:
Hello.Delighted to be able to help.
For increase in testicular size, both gonadotropins (FSH and LH) act together.
In addition to the joint action, both also have its own functions:
FSH stimulates the growth of seminiferous tubules for sperm production and LH acts on the Sertoli cells of the testis, which produce testosterone, which is essential for the development of secondary sexual characteristics of male.
I wish you good health.
Above answer was peer-reviewed by
 
Follow-up: What is the mechanism of action of androgens on growth in children? 11 hours later
Thanks Dr Munoz.

I read in a study increase in testicular size is due to growth of seminiferous tubules is due to increasing FSH, and therefore doesnt necessarily mean increase in LH.

Kindly could you clarify this final question.

Wishing you all the best.
Regards
 
 
Answered by Dr. Jose Ignacio Artero Munoz 4 hours later
Brief Answer:
Testicular size

Detailed Answer:
Hello.Delighted to be able to help.
Increase in testicular size is approximately 85% due to growth of seminiferous tubules which is dependent of FSH and 15% due to growth of Sertoli cells which is dependent of LH.Increased levels of FSH is more important but too is necessary LH levels increasing.
I Hope I have answered your query.If you do not have any clarifications, you can close the discussion and , please ,don’t forget to evaluate my answer.I wish you good health.
Above answer was peer-reviewed by
 
Follow-up: What is the mechanism of action of androgens on growth in children? 46 hours later
Thank you Dr Munoz your answers have been great.

At onset of puberty, does increase in testicular size ALWAYS mean increase in both the gonadotropins?

Why cannot it be, that the increased size is solely growth of seminiferous tubules? And nothing to do with growth of sertoli/LH levels?

Wishing you all the best. Thanks


 
 
Answered by Dr. Jose Ignacio Artero Munoz 3 hours later
Brief Answer:
Testicular Size

Detailed Answer:
Hello.
Delighted to be able to help.

The testicular size increased means elevation of levels of both gonadotropins (FSH and LH). Even before significant elevation of Fsh, is detected significant elevation of Lh. Consequently the increase in testicular size depends not only of growth of seminiferous tubules-fsh,also depends of growth of Sertoli cells-Lh.

However, as I said, the contribution to the increase in testicular size is approximately 85% due to growth of seminiferous tubules and 15% due to growth of Sertoli cells.


I Hope I have answered your query. If you do not have any clarifications, you can close the discussion and, please, don’t forget to evaluate my answer.I wish you good health.
Above answer was peer-reviewed by
 
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