The pituitary gland produces and releases human growth hormone (HGH) in response to specific biological signals in the body. The main stimulators of HGH production and secretion are:
- Growth hormone-releasing hormone (GHRH): This hormone is made by the hypothalamus and stimulates the pituitary gland to synthesize and secrete HGH. GHRH binds to receptors on somatotrope cells in the anterior pituitary, triggering events that lead to HGH gene transcription and translation.
- Ghrelin: This hormone is produced mainly by cells in the stomach and works synergistically with GHRH to amplify HGH release. Ghrelin levels rise just before meals, promoting hunger and feeding behavior. The ghrelin signal to the pituitary provides information about nutritional status.
- Sleep: Natural surges of HGH secretion occur during deep, non-REM sleep stages. The pattern of sleep and wakefulness regulates hypothalamic and pituitary function. Disrupted sleep can interfere with optimal HGH release.
- Exercise: Intense exercise that utilizes a large muscle mass transiently elevates HGH levels. However, the exercise-induced HGH secretion only lasts for about 30 minutes. The spike in HGH with exercise is modulated by ghrelin and sympathetic nervous system activity.
Other factors that help regulate HGH production and release include:
- Sex hormones like estrogen and testosterone
- Stress, mediated by the stress hormone cortisol
- Blood sugar levels - Low blood glucose can trigger the pituitary to make more HGH
- Thyroid hormones - Thyroid dysfunction can impact pituitary function
- Nutrition - Adequate protein and healthy fats help support natural HGH flow
- Age - HGH levels peak during puberty and decline significantly as we age
Abnormalities in the complex control system can lead to excess or insufficient HGH secretion and associated health issues:
- HGH deficiency in children and adolescents impacts linear growth. In adults, deficiency negatively affects bone density, muscle mass, blood lipids, and heart function.
- HGH excess, often due to pituitary tumors, fuels excessive growth in the young leading to gigantism or acromegaly if unchecked. Adults with too much HGH can experience joint swelling, headaches, impaired glucose metabolism among other effects.
If you suspect you may have a growth hormone imbalance, the endocrinologists at Hormone Harmony Clinic can help. We specialize in the diagnosis and treatment of pituitary gland issues using state-of-the-art testing and appropriately timed hormone replacement protocols. Contact us today to schedule a consultation with one of our highly trained HGH therapy experts.
In summary, the main factors that stimulate the anterior pituitary gland to synthesize and secrete human growth hormone include:
- Hypothalamic growth hormone-releasing hormone (GHRH)
- Ghrelin from the stomach
- Physiological cues during sleep
- Elevated catecholamines and sympathetic activity during intense exercise
This stimuli trigger the pituitary gland to release stored HGH into the blood to act on various tissues and exert regulatory effects on metabolism, growth, body composition and multiple biological processes. Imbalances in HGH can occur if any part of this complex neuroendocrine system is disrupted.