Somatropin (recombinant HGH)
Somatropin is recombinant human growth hormone (191-amino-acid), biosynthetically identical to pituitary GH. It is an approved drug for GH deficiency, Turner syndrome, chronic renal insufficiency, short stature and HIV wasting, and is the most thoroughly studied compound of the GH axis. It drives IGF-1 production, lipolysis and nitrogen retention; misuse for body composition and anti-ageing is widespread but off-label.
01 Overview
Somatropin is produced in E. coli or mammalian cells and dosed subcutaneously. In deficiency it restores linear growth in children and improves body composition, bone density and lipid profile in adults. Endogenous secretion is pulsatile; exogenous somatropin produces a sustained rise in IGF-1 that mediates most anabolic effects.
Outside approved indications it is used for fat loss, connective-tissue recovery and perceived anti-ageing benefit. Benefits on lean mass and fat mass in healthy adults are real but modest and reverse on cessation, and long-term supraphysiological use raises concerns about insulin resistance, oedema and possibly neoplasia. It is a WADA-prohibited substance at all times.
02 Mechanism
Binds the growth hormone receptor to activate JAK2/STAT5 signalling, directly promoting lipolysis and, via hepatic and local IGF-1 production, cell proliferation, protein synthesis and nitrogen retention.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Adult GH deficiency | 0.2–1 mg/day | SubQ | Titrated to IGF-1 in the age-adjusted reference range. |
| Body-composition (off-label) | 2–4 IU/day | SubQ | ~0.67-1.3 mg. Roughly 3 IU per mg. Non-medical use; unmonitored. |
| High off-label | 4–8 IU/day | SubQ | Markedly raises insulin-resistance and oedema risk. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Fat lossDirect lipolysis, most pronounced at visceral depots, over months of use. | -2 to -5 kg fat mass | Clinical | |
| Increased lean massNitrogen retention and IGF-1-driven protein synthesis; a portion is fluid/lean water rather than contractile tissue. | +1 to +3 kg | Clinical | |
| Raised IGF-1Dose-dependent rise in serum IGF-1, the biomarker used to titrate therapy. | Clinical | ||
| Improved recovery and sleepReported faster connective-tissue recovery and deeper slow-wave sleep; harder-quantified than body-composition endpoints. | Observational |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Fluid retention and oedemaSodium and water retention causing peripheral oedema, especially early and at higher doses. | Moderate | Very common, dose-related | Clinical | |
| Carpal tunnel syndromeMedian-nerve compression causing wrist/hand paraesthesia and pain. | Moderate | Common at higher doses | Clinical | |
| Insulin resistance / raised glucoseGH antagonises insulin, raising fasting glucose and, with high chronic dosing, risking overt diabetes. | Moderate | Common, dose-related | Clinical | |
| Acromegalic changes with chronic supraphysiological useSoft-tissue and bony overgrowth (hands, jaw, brow), organomegaly and cardiomyopathy mirroring acromegaly. | Severe | With prolonged high-dose misuse | Observational |
06 Commonly used with
What somatropin is combined with, and why. This is about intent rather than safety — the interactions table below covers what is dangerous. Nothing here is listed without what it costs.
| Compound | Frequency | Purpose & trade-off |
|---|---|---|
| Stacked compounds | ||
| Insulinexogenous, advanced protocols | GH raises blood glucose and induces insulin resistance, so advanced bodybuilders add insulin to drive nutrients into muscle and counter GH's diabetogenic effect for a stronger anabolic result.Trade-off: This is the most dangerous common pairing in the space — insulin can cause acute, potentially fatal hypoglycaemia, and the GH+insulin combination compounds long-term metabolic and organ-growth risks. | |
| IGF-1 LR3downstream mediator | Layered so the anabolic IGF-1 signal GH normally produces is supplemented directly, aiming for greater hypertrophy and recovery.Trade-off: IGF-1 on top of GH stacks hypoglycaemia risk and the theoretical concern that anything (including neoplastic tissue) is pushed to grow, with no human safety data for the combination. | |
| TestosteroneTRT/base dose | GH and testosterone are frequently run together because androgens amplify GH's anabolic and recomposition effects and support the training that justifies GH use.Trade-off: Testosterone adds its own suppression, aromatisation and cardiovascular considerations, so you inherit a full AAS side-effect profile on top of GH's cost and metabolic burden. | |
| Support & ancillaries | ||
| Metformin / glucose managementinsulin-sensitiser | Added to blunt the insulin resistance and elevated fasting glucose that chronic GH use reliably produces.Trade-off: It only partially offsets GH's metabolic effect and can mask, rather than resolve, a drift toward impaired glucose tolerance. | |
| Thyroid hormoneT3/T4) (low-dose | Sometimes added because GH increases peripheral T4-to-T3 conversion demand and users chase enhanced fat loss.Trade-off: Exogenous thyroid can suppress natural thyroid output and, if overdone, drive muscle loss, arrhythmia and heat intolerance — a real risk for a marginal gain. | |