HGH (Somatropin)
Also known as Human Growth Hormone, Somatropin, rhGH, Recombinant Growth Hormone, Genotropin, Norditropin, Omnitrope
HGH is recombinant human growth hormone, a 191 amino acid protein identical to what the pituitary makes. It is an approved drug for growth hormone deficiency and is used off-label for fat loss, muscle preservation, recovery, and anti-aging.
Overview
Human growth hormone is a 191 amino acid single chain protein made by the pituitary. Technically it is a protein rather than a small peptide, but it belongs in any peptide database because it is the hormone every secretagogue is trying to release. Recombinant somatropin has been available since 1985 and is approved for pediatric and adult growth hormone deficiency, Turner syndrome, chronic kidney disease in children, HIV wasting, short bowel syndrome, and other conditions. Brands include Genotropin, Norditropin, Humatrope, Omnitrope, and Saizen, and unlicensed generics dominate the grey market.
The clinical evidence in true deficiency is strong. Replacement in growth hormone deficient adults improves lean mass, reduces fat mass, improves lipid profiles, bone density, and quality of life. In healthy adults the picture is more modest. A frequently cited 1990 study in older men showed increased lean mass and reduced fat with 6 months of injections, and later meta-analyses of healthy older adults confirmed body composition changes of a few kilograms but found no improvement in strength or function and a meaningful rate of side effects like edema, joint pain, and carpal tunnel syndrome.
In sports and body composition circles, HGH is used at doses of 2 to 6 IU per day for fat loss, muscle fullness, and recovery, often for months at a time. The fat loss and water shifts are real; the effect on true muscle protein is smaller than most people expect and is amplified mainly when combined with anabolic hormones. The main concerns with sustained use are insulin resistance, elevated blood glucose, fluid retention, joint issues, and theoretical cancer promotion from chronically elevated IGF-1. Because it is a controlled prescription drug in most countries, the legal status is also very different from research peptides.
How it works
Somatropin binds the growth hormone receptor on the liver, muscle, fat, and bone, activating the JAK2-STAT5 signaling cascade. In the liver this drives production of IGF-1, which mediates most of the anabolic and growth promoting effects on muscle, cartilage, and bone. Growth hormone also has direct effects on fat cells, stimulating lipolysis and reducing lipid uptake, and on metabolism, where it raises blood glucose by opposing insulin and promoting fat oxidation. Exogenous somatropin suppresses the body's own pulsatile growth hormone production through negative feedback at the hypothalamus and pituitary, which is why the effects feel different from secretagogues and why some people split doses to mimic natural pulses.
What the research shows
- human RCTSix months of growth hormone in men over 60 increased lean mass by about 8 percent and reduced adipose mass by about 14 percent.
- human RCTMeta-analysis of healthy older adults found small gains in lean mass and losses in fat mass but no improvement in strength, with higher rates of edema, joint pain, and carpal tunnel.
- clinical (approved drug)Growth hormone replacement in deficient adults improves body composition, lipid profile, bone density, and quality of life.
- human RCTGrowth hormone increased sprint capacity by about 4 percent in recreational athletes but did not improve strength, power, or endurance.
- human RCTGrowth hormone administration in healthy adults reduces insulin sensitivity and raises fasting glucose in a dose dependent way.
Evidence labels: rodent and in vitro mean no human data for that finding. Human pilot means small, often uncontrolled. Human RCT means randomized and controlled. Clinical means an approved drug with regulatory data.
Dose calculator
U-100 insulin syringeUnits are a volume on the syringe, not an amount of peptide. Concentration changes every time you change the water volume. The standalone calculator explains the math.
Dosing and protocol
1-2 IU daily for anti-aging and recovery; 3-6 IU for body composition; medical replacement is typically weight based and lower
3-6 months minimum for body composition; medical replacement is ongoing
Morning on waking or before bed are the most common. Splitting AM and PM reduces the peak and may reduce side effects. Some inject post-training.
| Vial | Suggested water | Concentration | Low dose draw |
|---|---|---|---|
| 10 IU | 1 mL | 10 IU/mL | 10 units |
| 12 IU | 1 mL | 12 IU/mL | 8.3 units |
Lyophilized: fridge 2-8C; some products tolerate room temperature briefly. Reconstituted: fridge 2-8C, use within 2-4 weeks depending on product.
Cautions
- ▲Fluid retention, swollen hands and feet, joint pain, and carpal tunnel symptoms are dose related and very common above 2 IU daily.
- ▲Raises blood glucose and reduces insulin sensitivity; monitor fasting glucose and HbA1c, especially with prolonged use.
- ▲Suppresses your own growth hormone production while you use it, unlike secretagogues.
- ▲Chronically elevated IGF-1 is a theoretical cancer risk; do not use with any active or prior malignancy.
- ▲Counterfeit and underdosed product is rampant on the grey market; brand pens from pharmacies are the only reliable source.
Commonly stacked with
Adds direct IGF-1 signaling on top of the growth hormone driven liver IGF-1 for a stronger anabolic effect; increases hypoglycemia risk.
Common recovery pairing; growth hormone raises IGF-1 and collagen synthesis while BPC-157 targets local tissue repair.
Systemic recovery stack alongside growth hormone for injury rehabilitation.
Frequently asked
How much muscle will HGH build?
Less than most people think. In healthy adults it adds a few pounds of lean mass over months, and a good portion of that is water and connective tissue rather than contractile muscle. Strength does not improve in controlled studies. The fat loss and the fuller look are more reliable than the muscle gain.
What is a good starting dose?
Most people start at 1-2 IU daily and hold there for a few weeks before considering an increase. Side effects like tingling hands and water retention scale with dose, and 2 IU is plenty for recovery and skin benefits. Doses of 4 IU and up are body composition territory with a much higher side effect load.
Is a secretagogue like CJC-1295 and ipamorelin as good as HGH?
No. Secretagogues produce pulses of your own growth hormone and are limited by what your pituitary can release, which is why IGF-1 rises modestly. HGH delivers a set amount regardless. The secretagogues are cheaper, keep your own production intact, and have fewer side effects, but they are weaker.
How do I convert IU to mg?
The current standard is 3 IU per mg of somatropin, so a 10 IU vial holds about 3.33 mg and a 12 IU vial about 4 mg. Older references used slightly different factors, which is why you sometimes see conflicting numbers.
Does it cause diabetes?
It raises blood glucose and reduces insulin sensitivity while you are on it, and the effect is dose dependent. In people who are already prediabetic that can be enough to push them over. Regular bloodwork is not optional with sustained use.
References
- Effects of human growth hormone in men over 60 years old. New England Journal of Medicine, 1990
- Systematic review: the safety and efficacy of growth hormone in the healthy elderly. Annals of Internal Medicine, 2007
- The effects of growth hormone on body composition and physical performance in recreational athletes: a randomized trial. Annals of Internal Medicine, 2010
- Consensus guidelines for the diagnosis and treatment of adults with growth hormone deficiency. European Journal of Endocrinology, 2007