What Is Sermorelin?
| What it is | A synthetic copy of amino acids 1 to 29 of human growth hormone releasing hormone |
|---|---|
| Other names | GRF 1-29 NH2, GHRH (1-29) and sermorelin acetate; brand name Geref |
| Molar mass | About 3,358 g/mol |
| Target | The GHRH receptor on growth hormone cells in the pituitary gland |
| Former uses | A test of pituitary function and a treatment for children with idiopathic growth hormone deficiency |
| Market history | US approval in 1990 (test) and 1997 (treatment); discontinued in 2008 |
| Status | No current licence in the EU, UK or US; banned in sport under WADA class S2 |
Sermorelin is a peptide, a short chain of amino acids made in a laboratory. It matches the opening section of growth hormone releasing hormone, usually shortened to GHRH, which the brain uses to switch on growth hormone release.
The Shortest Working Piece
Natural GHRH in humans is 44 amino acids long. Soon after it was discovered, scientists noticed that the first 29 were enough to give the full effect. Sermorelin is exactly that stretch, with the same small chemical cap at its end as the natural hormone. Its sequence begins Tyr-Ala-Asp-Ala-Ile-Phe and ends Ile-Met-Ser-Arg.
What Happens in the Body
- The message: sermorelin attaches to the GHRH receptor on growth hormone cells in the pituitary gland.
- The response: those cells release growth hormone that they have made and stored.
- The knock-on effect: growth hormone travels to the liver and other tissues, which then make more IGF-1, the growth factor behind many of its effects.
- The brake: the body's own off switch, a hormone called somatostatin, still works, so release comes in bursts rather than a steady flood.
How It Differs From Growth Hormone
Injected growth hormone, sold as somatropin, goes straight into the bloodstream whether the pituitary is working or not. Sermorelin can only help if the pituitary still has healthy growth hormone cells, because it acts by asking them to work harder. It therefore made no sense for people whose gland was damaged or missing.
Supporters of GHRH-based treatment argued that keeping the body's natural rhythm and feedback in place might lower the risk of overdoing it. That idea was attractive, but it was never tested head to head against growth hormone in large trials of adults.
In Short
- Sermorelin is the first 29 amino acids of the brain's growth hormone releasing signal.
- It works through the pituitary, not instead of it.
- Its effect depends on a pituitary that can still respond.
- It was approved for children, never for healthy adults.