Recombinant human growth hormone: a short serum half-life with long-acting effects
Bioidentical human growth hormone, produced recombinantly and identical to the pituitary's own 191-amino-acid protein. It leaves the blood in a few hours and its effects last far longer, which is the single fact that explains how it is dosed and measured.
- Also known as
- Somatropin, rHGH, Human Growth Hormone, Genotropin, Norditropin, Humatrope, Omnitrope, Somatropin (rhGH)
- Class
- Growth hormone and IGF-1
- Regulatory status
- FDA APPROVED for adult GHD, HIV wasting, Turner syndrome, and other indications. Off-label anti-aging use.
- Modelled half-life
- 3.8 h
- Time to peak
- 3 h
- Formulation
- Aqueous (reconstituted powder) · fragile protein
- Before mixing
- Sealed powder tolerates room temperature in transit, but keep it refrigerated at 2–8 °C (36–46 °F) for anything beyond a few weeks, or frozen for months. Keep it dark — the carton it shipped in is doing a job.
- After mixing
- Once reconstituted with bacteriostatic water: refrigerate at 2–8 °C and use within about 28 days. The benzyl alcohol in bacteriostatic water is what buys that window — plain sterile water has no preservative, so a vial mixed with it should be treated as one sitting only. Kits are usually ten vials: only the one you mixed is on that 28-day clock — the sealed ones keep their own, much longer shelf life, so store them as powder, not as solution.
- What ruins it
- Do not freeze a reconstituted vial. Repeated freeze–thaw is one of the more reliable ways to degrade a peptide.
- Handling caveat
- General handling practice for this formulation. Your supplier’s own insert or COA overrides anything here.
The hormone is a signal; IGF-1 is the effect
Established clinical use Growth hormone acts directly on some tissues and indirectly on many more by stimulating hepatic production of insulin-like growth factor 1. GH itself is released in pulses, mostly at night, and is cleared from serum with a half-life the app models at under four hours. IGF-1 circulates bound to binding proteins with a half-life of many hours and is far more stable across the day. So a random GH measurement is close to uninterpretable, and IGF-1 is what gets measured instead.
That is why the monitoring panel is built around IGF-1 rather than around growth hormone: it integrates the signal over time in a way a serum GH cannot. It is also why the effects of a daily injection do not track the injection's own curve. The compound is gone by morning; what it set in motion is not.
The consequence for anyone reading a protocol is that titrating by feel is not available here. Body-composition change on GH takes months, the effects that appear early are mostly fluid, and the marker that tells you where you are is a blood test. The IGF-1 page covers what the number means and why the reference range is age-dependent.
Approved use, and what the off-label use borrows from it
Established clinical use Somatropin is approved for a specific set of indications, adult growth hormone deficiency among them, and in that population the evidence for improved body composition, bone density and quality of life is solid. Diagnosing adult deficiency is not a matter of a low IGF-1: it requires provocative stimulation testing, because IGF-1 overlaps substantially between deficient and sufficient adults.
Off-label or community practice Use in adults without a deficiency diagnosis is off-label, and the evidence base is genuinely different. Meta-analyses in healthy older adults have found small changes in lean and fat mass with no demonstrated improvement in strength or function, alongside a consistent increase in oedema, arthralgia and carpal tunnel syndrome. Whatever else that is, it is not the same finding as the deficiency literature, and using the deficiency evidence to support the off-label use is the most common error in writing about this compound.
The adverse effects that define the off-label experience are dose-dependent and largely reversible: fluid retention, joint aches, carpal tunnel symptoms and reduced insulin sensitivity. The insulin item is the one that shows up on a panel rather than in a symptom, which is why fasting glucose and HbA1c sit alongside IGF-1 on the app's monitoring list.
Handling, and the counterfeit problem
Somatropin is a protein, and proteins denature. The app flags it as fragile: it ships lyophilised or as a refrigerated solution, it does not tolerate freezing once reconstituted, and it does not survive heat or agitation. The storage rule in the fact box is the app's own, with its handling caveat attached. A vial that has been through a warm delivery is a vial of unknown potency, and there is no way to tell by looking.
The grey market for this compound is large and the counterfeit rate is high — a point the app's own drawbacks list makes. This site names no vendor, no clinic and no testing service, and it will not: a page that ranks for a compound and then tells you where to buy it has stopped being information. What can be said usefully is that identity and potency are unverifiable outside a regulated supply chain, and that a product with a real prescription behind it is the only version of this where those questions have an answer.
Everything above is a description of what the literature and clinical practice report. Growth hormone is a prescription drug, the diagnosis that justifies it requires testing, and the effects described here belong in front of the clinician who prescribes rather than being managed from a page.
How long one dose lasts
pkCurve function.
The vertical axis is relative: the shape carries across people, the absolute
concentration does not.Try other intervals on the half-life and steady-state calculator, which runs the same function against whatever cadence you type.
The dosing rows the app records
Established clinical use Reproduced from the app’s reference so you can see what it holds, not as a recommendation. Which row applies to a particular person, if any, is a clinical decision this page does not make — and rows describing supraphysiological or post-cycle use are filtered out before this table is built, so what you see here is a subset.
| Label | Amount | Route and frequency | Duration recorded |
|---|---|---|---|
| Anti-aging / Wellness | 1-2 IU/day | Daily SubQ before bed or fasted AM | 3-6 months minimum |
| Body Composition | 2-4 IU/day | Daily SubQ — some split AM and post-workout | 3-6 months |
| Medical (GHD) | Physician titrated | Daily | Ongoing as prescribed |
What the app monitors alongside it
The panel below is the app’s own monitoring note for Recombinant HGH, verbatim. The analytes in it that have a page here are linked; those pages cover what each one measures, which assay produced it and how to read a trend.
- Monitoring panel
- IGF-1 (critical — maintain upper third of normal range), Fasting glucose, HbA1c, Lipid panel every 3 months. Wrist and joint assessment for carpal tunnel.
Drawbacks and risks the app records
From the app's own entry. Note the split between the effects that are dose-dependent and reversible and the ones about sourcing — they call for completely different responses.
- Expensive — often $500-2000+/month without insurance
- Requires refrigeration
- Injection only — daily SubQ
- Carpal tunnel syndrome common at higher doses
- Water retention and joint pain at high doses
- Insulin resistance risk — glucose monitoring required
- Potential for acromegaly features at chronic supraphysiological doses
- Expensive — especially pharma grade
- Slow results — months to see effects
- Water retention, carpal tunnel, joint aches
- Can raise blood glucose / insulin resistance
- Frequently counterfeit in grey market
- Requires refrigeration and proper handling
Interaction rules that name Recombinant HGH
From the app’s interaction data, filtered so no rule naming a compound this site does not publish appears. Not exhaustive, and not a safety clearance: a combination that is not listed is one nobody has documented here, which is not the same as one that is fine. The combination checker has the rest.
IGF-1 Hypoglycemia Risk Amplified
Both HGH and IGF-1 LR3 lower blood sugar. Combining them significantly amplifies hypoglycemia risk, especially post-workout when glucose is already depleted. Fast-acting carbohydrates must be on hand.
What to watch: Fasting glucose, post-injection glucose monitoring, always have fast carbohydrates available.
Insulin + Growth Hormone — The Combination Behind the Case Reports
Growth hormone raises blood glucose and induces insulin resistance over hours to days; insulin lowers glucose over minutes. The two effects run on completely different clocks, which is exactly why the pairing is dangerous: an insulin amount that was tolerable alongside GH one week can be far too much on a day the GH is skipped, the dose changes, or food does not arrive on schedule. This is the combination that appears in the published bodybuilding fatality and hypoglycemic brain injury reports.
What to watch: Fasting glucose, HbA1c and IGF-1. Glucose checked before and after each insulin dose and again before sleep. Anyone using both should have fast-acting carbohydrate to hand and a person nearby who knows what has been taken.
Questions people actually ask
Why is IGF-1 measured rather than growth hormone?
Because GH is pulsatile and clears in a few hours, so a single measurement mostly reports where in a pulse the draw happened. IGF-1 is stable across the day and reflects GH exposure over a longer window, which is what makes it usable as a titration marker.
Do growth hormone secretagogues do the same thing?
They raise the body's own GH release rather than supplying GH, so they work within the pituitary's feedback loops and produce a pulsatile rather than a continuous signal. That is a real pharmacological difference, and it is not the same as saying one is safer or more effective. Sermorelin, CJC-1295, ipamorelin and MK-677 each have a page here.
How long does one injection last in the blood?
The app models a serum half-life of under four hours, so it is essentially gone within a day. The IGF-1 elevation it produces lasts considerably longer, which is why daily administration produces a sustained effect from a compound with a short half-life.
What does "fragile" mean in the storage rule?
That it is a protein whose structure is the thing doing the work, so heat, freezing and mechanical agitation can destroy activity without changing the appearance of the vial. The app flags fragility separately from the storage temperature for that reason.
Where the load-bearing numbers come from
Named rather than linked. Publisher URLs move, and a citation that resolves to a 404 two years from now is worse than one you can search for by name — every entry below is findable from the title and year alone.
- GH pulsatility and IGF-1 as the integrated marker
- Standard endocrinology references on the GH/IGF-1 axis
- Effects in adult growth hormone deficiency
- Endocrine Society clinical practice guideline on adult growth hormone deficiency and the underlying trial literature
- Effects in healthy older adults
- Systematic review of growth hormone in the healthy elderly, Annals of Internal Medicine, 2007, and subsequent meta-analyses
- Approved indications, storage rule and fragility flag
- app.html’s own approval, TL_STORAGE and TL_PK fields, lifted at build time
IGF-1 every few months against a daily injection is a trend, not a number. TherapyLog charts it against the dose that produced it.
Save this dose to your log