Sermorelin vs HGH (somatropin)
Every row cites its source. Where a cell reflects our own reading of the evidence rather than an external source, the row says so.
| Dimension | Sermorelin | HGH (somatropin) | Source |
|---|---|---|---|
| What is injected | A 29-amino-acid GHRH fragment that signals the pituitary | Recombinant human growth hormone itself | source |
| Where it acts | Upstream: GHRH receptor on pituitary somatotrophs | Downstream: GH receptors throughout the body | source |
| Feedback loops | Preserved: GH stays pulsatile; somatostatin and IGF-I still regulate output | Bypassed: exposure set by the injected dose, not the axis | source |
| FDA status | No approved product since 2008; compounded only; not withdrawn for safety or effectiveness | FDA-approved (somatropin products such as Norditropin), prescription only | source |
| Evidence in healthy older adults | Small trials: GH up reliably; IGF-1 inconsistently; 2 of 6 strength measures in one study; no outcome trials | Pooled RCTs: about 2 kg lean mass gain and 2 kg fat loss, no functional gains, and significantly more adverse events | source |
| Documented adverse effects | Flushing and injection-site pain most common; transient hyperlipidemia in one trial; long-term unknown | Edema, arthralgia, carpal tunnel syndrome, gynecomastia, glucose impairment in healthy-elderly RCTs | source |
| Monitoring model | No label; trials tracked IGF-1, which is the rational marker to discuss with a prescriber | Label-directed titration with serum IGF-1 monitoring | source |
| Requirement for a working pituitary | Essential: no functional somatotrophs, no effect | None: works even with pituitary failure | source |
Somatropin is the hormone; sermorelin is a request for the hormone. Somatropin carries FDA approval, decades of evidence, and documented adverse-effect rates in healthy older adults; sermorelin carries a discontinued approval, a pulse-preserving mechanism, and adult trials that measured hormone levels more than outcomes. Anyone choosing between them with a clinician should know that only one of the two is an approved drug today.