Can exogenous thyroid hormone use cause...

[magic32]

...elevated estro levels, gyno, decreased libido, etc.?

Yes, indirectly via the negative feedback loop.


Just an FYI, aas is not always the culprit:

Role of Thyroid on Testis Function
Thyroxin can affect the male reproductive system. Hyperthyroidism has been associated with an increase in total serum testosterone levels but with normal unbound or bioactive testosterone . This is caused by the increase in the SHBG levels associated with hyperthyroidism. The increase in SHBG causes a relative decrease in the free testosterone levels, which leads to an elevation of the serum LH (negative feedback), a further increase in serum testosterone and, by peripheral conversion, an increase in serum estradiol. As a result of the increase in circulating estrogens, these men with hyperthyroidism may complain of or present with gynecomastia , spider angiomas, and a decrease in libido.25,26 Treatment of the thyrotoxicosis reverses the symptoms and signs of the disorder.

In hypothyroidism, LH and FSH are usually elevated, which is consistent with testicular resistance to gonadotropins. The serum testosterone and SHBG are usually decreased, while the free testosterone has been reported to be increased, decreased, or normal. Some men with hypothyroidism may complain of ED; in this setting, replacement with thyroxin rarely improves potency.


Source:
Jacob Rajfer, MD
Relationship Between Testosterone and Erectile Dysfunction
Rev Urol. 2000 Spring; 2(2): 122–128.
Relationship Between Testosterone and Erectile Dysfunction

[Bert]

Interevedesting.