Educational reference only. Nothing on this page constitutes medical advice or encourages personal use of this compound. Always consult a qualified healthcare provider before any decision involving your health.

HGH / Somatropin

Somatropin · Recombinant Human Growth Hormone · rhGH

Animal replicated

FDA-approvedPeptide Hormone Growth Hormone Recombinant Protein

RouteInjectableFDA-approved

Evidence grade: Animal replicated

Effect demonstrated in multiple animal studies; human data sparse or extrapolated. Grades summarize evidence quality, not whether a compound is appropriate, legal, or risk-free.

At a glance

What it is: Human Growth Hormone — Recombinant Somatropin — FDA Approved — The GH Axis Foundation Chapter — Peptide Hormone, Growth Hormone, Recombinant Protein.
Why people use it: Used primarily for muscle and performance and tissue repair and healing.
What the evidence supports: This is the most pharmacologically important distinction in the entire GH chapter — and the key to understanding why secretagogues and exogenous HGH are not equivalent.

If you only read one thing

Exogenous HGH injection replaces a hormone that the body normally secretes in large nocturnal pulses with what is effectively a pharmacological dose of continuous exposure. A pituitary somatotroph cell releasing GH in response to GHRH produces a large, brief pulse that is mostly cleared from circulation within 30 minutes. A subcutaneous HGH injection produces a slower, broader pharmacokinetic profile that sustains GH elevation for 4-6 hours — a fundamentally different exposure pattern. For confirmed GH-deficient adults, this replacement produces profound and well-documented clinical benefits regardless of the non-physiological delivery pattern. For eugonadal adults with normal GH secretion: exogenous HGH adds to existing GH output, producing supraphysiological IGF-1 levels that drive both the desired body composition effects and the dose-dependent adverse effects — edema, arthralgia, carpal tunnel, glucose intolerance. The entire secretagogue category (sermorelin, CJC-1295, ipamorelin, MK-677) was developed to exploit the fact that preserving pulsatile GH release through stimulation of endogenous production avoids the continuous-exposure pharmacokinetics of direct HGH injection, potentially offering more physiological profiles at lower risk — and at substantially lower cost.

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Published literature

10human RCTs5human studies3animal2in vitro

Somatropin has extensive controlled and registry evidence for approved growth-hormone-deficiency and wasting indications; these counts do not validate anti-aging use in eugonadal adults or oral/topical routes.

Evidence reality check

Human evidence

15 human studies

10 randomized; 5 observational.

Preclinical base

5 lab signals

3 animal; 2 in-vitro/mechanistic.

Evidence snapshot

This is the most pharmacologically important distinction in the entire GH chapter — and the key to understanding why secretagogues and exogenous HGH are not equivalent.

From the chapter quick-reference block.

Does the age-related decline in GH secretion in otherwise healthy older adults (not meeting criteria for structural GHD) represent a deficiency state warranting treatment? The 'somatopause' concept proposes that declining GH/IGF-1 in aging contributes to sarcopenia, increased fat, and reduced bone density. No large RCT has definitively established that HGH therapy in non-GHD older adults produces net clinical benefit exceeding risk.
What are the long-term cancer risks of community HGH use at performance doses (2-4 IU/day) that chronically maintain IGF-1 at +2 to +3 SDS? The KIMS and HypoCCS registries confirm safety at physiological replacement doses — they provide no data for supraphysiological community use.
Will the once-weekly formulations (Sogroya, Skytrofa) demonstrate superiority over daily somatropin for outcomes beyond adherence? The foresiGHt trial showed equivalence for body composition endpoints — long-term data on bone density, quality of life, and metabolic outcomes with once-weekly vs daily delivery is accumulating.
Does the more physiological pulsatile GH profile from secretagogues produce meaningfully better safety outcomes than daily HGH injection at equivalent IGF-1 levels? The pharmacological prediction (pulsatile is better) has not been directly tested in controlled human trials comparing secretagogues to equivalent-dose HGH.

Categories

Muscle & Performance Healing & Recovery Sleep & Recovery Weight Loss & Metabolic

Properties

Active malignancy: hard stopWADA S2✓ FDA-approved✓ Human RCTHPTA: stimulating

Evidence

CAnimal replicated

The GH Axis — Why This Chapter Is the Foundation

GH is not simply a muscle-building hormone. It is the master regulator of growth, metabolism, body composition, bone density, immune function, and tissue repair throughout the adult lifespan. GH secretion is pulsatile — largest pulses occur during slow-wave sleep; controlled by GHRH (stimulatory) and somatostatin (inhibitory) from the hypothalamus; and ghrelin (stimulatory) from the stomach and pituitary. GH acts on the liver to produce IGF-1 (Insulin-like Growth Factor 1), which mediates most of GH's growth-promoting and anabolic effects. Every secretagogue compound in this reference — sermorelin, tesamorelin, CJC-1295, ipamorelin, GHRP-2, GHRP-6, MK-677 — works by stimulating the pituitary to release more of this endogenous GH. Understanding exogenous HGH is therefore the foundation for understanding the entire secretagogue category.

Adult GHD — The Medical Indication

Adult growth hormone deficiency (GHD) is a recognized medical syndrome occurring after the growth phase is complete. Caused by: pituitary adenoma and its treatment (most common); hypothalamic damage; irradiation; traumatic brain injury; idiopathic. Symptoms: increased visceral fat; reduced lean mass; reduced bone density; reduced exercise capacity; impaired lipid profile (↑LDL, ↓HDL); reduced quality of life; fatigue; depression-like symptoms. Diagnosis: GH stimulation test (insulin tolerance test or GHRH+arginine) with peak GH <3-9 ng/mL threshold depending on test and BMI; plus low IGF-1 (<-2 SDS). Treatment: somatropin replacement — produces significant improvement in all symptoms with Grade A evidence.

FDA-Approved Indications

Children: GHD; Turner syndrome; Prader-Willi syndrome; Noonan syndrome; chronic renal insufficiency; SGA (small for gestational age); SHOX deficiency; idiopathic short stature (ISS). Adults: GHD (adult onset or childhood onset continuing to adulthood); HIV-associated wasting/cachexia (Serostim); short bowel syndrome (Zorbtive, up to 4 weeks). NOT FDA-approved: anti-aging; body composition enhancement in eugonadal adults without GHD; athletic performance enhancement. Schedule of control: somatropin is a prescription biologic, not a scheduled controlled substance — but prescribing for non-approved indications without medical necessity is regulated.

July 2025 — The Once-Weekly Revolution

Skytrofa (lonapegsomatropin, Ascendis Pharma) received FDA approval for adult GHD in July 2025 — the first once-weekly GH specifically indicated for the adult indication after already being approved for pediatric GHD. Based on foresiGHt Phase 3 trial (n=259 adults with GHD; ages 23-80): superior to placebo for trunk fat reduction and lean mass increase at Week 38; comparable safety and efficacy to daily somatropin. Sogroya (somapacitan, Novo Nordisk) was the first once-weekly GH for adult GHD, approved earlier. The once-weekly formulation advantage: dramatically improved adherence in a condition where daily injection burden is a known treatment barrier.

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CIT Stack

Shared goal · muscle

GH stack plus tesamorelin: a community combination built from GH-axis peptides with different regulatory identities, not a single FDA-approved product.

Human Chorionic Gonadotropin

Same class · Peptide Hormone

FDA-Approved for Fertility and Male Hypogonadism. The Most Important Hormone in Post-Cycle Therapy. The Active Ingredient in the Simeons 500-Calorie Diet — a Fraud With Its Own FDA Warning. WADA S2 Banned. A Tumor Marker. Three Completely Different Identities in One Glycoprotein.

Sermorelin