HGH (Somatropin)
Human Growth Hormone | 191aa Recombinant Growth Hormone
Human Growth Hormone (HGH), also known as somatropin or somatotropin, is a 191 amino acid single-chain polypeptide hormone naturally produced by the anterior pituitary gland. Recombinant HGH (rhGH/somatropin) is bioidentical to endogenous growth hormone and is FDA-approved for growth hormone deficiency in children and adults, as well as several other conditions. The '191aa' designation refers to its complete 191 amino acid structure, distinguishing it from older 192aa formulations. HGH regulates growth, metabolism, body composition, and numerous physiological processes through direct actions and via stimulating IGF-1 production.
Daily dose
1-4 IU (0.33-1.33 mg)
Frequency
Once daily
Cycle length
3-6+ months
Storage
2-8°C
Key benefits
Improved body composition (fat loss, lean mass gain), enhanced bone density, better lipid profile, increased energy and recovery, improved skin/hair, better quality of life
How it works
Binds GH receptors, activates JAK2-STAT5 pathway. Direct effects: lipolysis, protein synthesis. Indirect effects via IGF-1: growth, cell proliferation, anabolism. Half-life ~3 hours subcutaneously.
Dosage protocols
Goal
Medical Replacement
Dose
0.15-0.8 mg/day · Once daily
Route
SubQ injection
Goal
Anti-Aging (Conservative)
Dose
1-2 IU/day · Once daily
Route
SubQ injection
Goal
Body Recomposition
Dose
2-4 IU/day · Once or twice daily
Route
SubQ injection
Research indications
growth Hormone
body Composition
anti Aging
recovery
Administration
Interactions
Safety notes
FDA-approved only for specific conditions - off-label use has risks
Start low, increase gradually to minimize side effects
Monitor blood glucose - causes insulin resistance
Monitor thyroid function - can unmask hypothyroidism
Contraindicated with active cancer
Carpal tunnel syndrome common but usually temporary
Research studies
KIMS Long-Term Safety Study (2022)
Worldwide observational study | 15,809 patients | Mean 5.3 years follow-up | Adult GHD
Largest long-term safety study of GH replacement showing de novo cancer incidence comparable to general population (SIR 0.92). Supports safety of long-term GH replacement in routine clinical practice.
View study →Effects on Morbidity - Systematic Review (2014)
Systematic review of RCTs | Cardiovascular and bone metabolism endpoints
Positive effects demonstrated on cardiovascular surrogate markers and bone metabolism. Suggests potential positive effect on CVD and fracture risk, though study design limitations noted.
View study →Adult GHD Clinical Syndrome Characterization (2011)
Multiple studies | Clinical manifestations and treatment response
Established the syndrome of adult GH deficiency: decreased exercise tolerance, reduced mood/well-being, increased central adiposity, hyperlipidemia, reduced bone density, and atherogenesis predisposition.
View study →GH-Thyroid Hormone Interaction Study (2011)
Hypopituitary patients | T4/T3 conversion effects | Hypothyroidism unmasking
Demonstrated GH replacement can unmask central hypothyroidism in 36-47% of apparently euthyroid patients by increasing T4 to T3 conversion and reducing free T4 levels.
View study →Long-term Efficacy and Safety in Adult GHD (2005)
Systematic review | Body composition, bone density, quality of life outcomes
Established that long-term somatropin administration improves body composition, muscle strength, quality of life, bone mass/density, and lipoprotein patterns in GH-deficient adults.
View study →GENOTROPIN Clinical Trials Program (1990s-2000s)
6 randomized clinical trials | 172 adult GHD patients | Placebo-controlled
Pivotal trials demonstrating efficacy of somatropin for adult growth hormone deficiency, establishing body composition benefits and optimal dosing strategies.
View study →