From the Research
Pituitary adenomas can significantly affect sex hormone binding globulin (SHBG) levels, primarily through their impact on hormone production, with the most recent evidence suggesting that SHBG levels can be elevated in certain types of pituitary adenomas, such as TSH-secreting pituitary adenomas 1.
Impact of Pituitary Adenomas on SHBG Levels
The relationship between pituitary adenomas and SHBG levels is complex and depends on the type of hormone secreted by the adenoma.
- Adenomas that secrete excess growth hormone (as in acromegaly) or prolactin (as in prolactinomas) can increase SHBG levels.
- Conversely, adenomas that cause hypopituitarism or those that secrete ACTH (leading to Cushing's disease) often decrease SHBG levels.
Regulation of SHBG Production
SHBG production in the liver is regulated by various hormones under pituitary control, including:
- Estrogens and thyroid hormones, which increase SHBG synthesis
- Androgens, growth hormone, insulin, and cortisol, which decrease it
Clinical Implications
The altered SHBG levels can affect the amount of free (biologically active) sex hormones in circulation, potentially causing symptoms like:
- Menstrual irregularities
- Decreased libido
- Erectile dysfunction
- Infertility
Treatment
Treatment typically focuses on addressing the underlying adenoma through medication (such as dopamine agonists for prolactinomas) 2, surgery, or radiation therapy, which can normalize SHBG levels and restore hormonal balance.
- Recent studies have also explored the use of cabergoline in the treatment of other tumors, such as breast cancer, pancreatic neuroendocrine tumors, and lung cancer 2.
- The medical management of growth hormone-secreting pituitary adenomas has also been studied, with options including dopamine agonists, somatostatin analogs, and GH receptor antagonists 3.