What HGH (Somatropin) is
Somatropin is recombinant human growth hormone, identical to the pituitary 191-amino-acid protein and FDA approved for growth hormone deficiency under many brands. Gray-market generic HGH is one of the most-tested compounds in the PTDS dataset, and the testing matters more here than anywhere else: quality varies, and HGH has a failure mode most peptides do not, dimerization.
Dimer content is worth understanding before buying. Growth hormone monomers can pair into dimers that assay as mass but are biologically inferior, so two vials with identical mass can differ in usable hormone. Recent PTDS tests report dimer percentage separately; our COA reader flags dimer above 0.75% when a certificate reports it.
Reconstitution math
Concentration is everything: the same 10 IU vial gives a different draw for every amount of bacteriostatic water you add. The table uses the common 2 mL setup for each vial size, which puts every unit on a U-100 insulin syringe at 0.05 IU for the default vial. Dashes mark draws too small to measure or larger than the syringe.
| Vial | BAC water | Concentration | 1 IU | 2 IU | 3 IU | 4 IU |
|---|---|---|---|---|---|---|
| 10 IU | 2 mL | 5 IU/mL | 20 u | 40 u | 60 u | 80 u |
| 12 IU | 2 mL | 6 IU/mL | 16.7 u | 33.3 u | 50 u | 66.7 u |
| 24 IU | 2 mL | 12 IU/mL | 8.3 u | 16.7 u | 25 u | 33.3 u |
| 36 IU | 2 mL | 18 IU/mL | 5.6 u | 11.1 u | 16.7 u | 22.2 u |
Dosing and protocol
Community protocols: 1 to 2 IU daily for recovery and longevity, 2 to 4 IU daily for body composition; clinical replacement dosing is weight-based per the labels.
HGH is dosed in international units: 1 mg equals about 3 IU. Community protocols run 1 to 2 IU daily for recovery and skin or sleep benefits, and 2 to 4 IU daily for body composition, usually five to seven days a week, with timing split between morning and pre-bed camps. The HGH calculator handles the IU math directly, including the mg conversion printed on some vials.
Pharmacokinetics
HGH (Somatropin) has published human pharmacokinetics: apparent half-life around 3 hours subcutaneously, peak at 3 to 6 hours. The curves below are normalized one-compartment models built from the cited half-life, the same math the Planner uses. They show shape and timing, not absolute blood levels.
Storage and handling
Lyophilized vials keep best cold, dark, and dry; refrigeration is the community default and freezing lyophilized powder is common for long holds. After reconstitution, refrigerate at 2 to 8 C, do not freeze the solution, and date the vial. Bacteriostatic water's preservative keeps multi-dose use practical for about 28 days by USP convention, though our 120-day stability study found the preservative itself outlasts that window.
HGH is the most fragile compound on this page. It is sensitive to agitation (swirl, never shake), heat, and repeated temperature swings; the approved products are refrigerated even before reconstitution. Treat kits accordingly in transit and store reconstituted vials cold without exception.
Got a certificate of analysis with your vial? Run it through our COA Reader: it reads the report in plain English, checks purity and mass against the label claim, and links the testing lab’s own verification page. Our guide to reading a COA explains what the numbers do and do not tell you.
Sources
- Genotropin prescribing information (Pfizer)
- Norditropin prescribing information (Novo Nordisk)
- Bidlingmaier and Strasburger, Growth hormone assays, Clin Chem Lab Med 2010