Growth Hormone Dose Calculator

Why growth hormone is dosed in IU

Recombinant human growth hormone — somatropin — is a 191-amino-acid polypeptide that is structurally identical to endogenous pituitary HGH. It is FDA-approved for several conditions, including pediatric growth hormone deficiency, adult growth hormone deficiency, Turner syndrome, idiopathic short stature, AIDS-associated wasting, and short bowel syndrome, and is sold under brand names including Genotropin, Humatrope, Norditropin, Saizen, and Omnitrope.

Unlike most research peptides, somatropin is conventionally measured in International Units rather than milligrams. International Units describe biological activity rather than mass, which makes them a more direct indicator of expected effect at the receptor. By long-standing clinical convention, 1 mg of somatropin is treated as approximately 3 IU, so a 10 IU vial corresponds to about 3.33 mg of peptide and a 6 IU vial to roughly 2 mg. Vials are almost always labelled in IU; the calculator above accepts either unit. Among reference peptides, HCG is the other compound routinely dosed in IU rather than milligrams, for the same activity-based labelling reason.

Reconstitution is straightforward but the glycoprotein is fragile. Inject bacteriostatic water slowly along the inner wall of the vial, swirl gently, and refrigerate the solution at 2–8 °C. Brand-specific in-use stability windows are typically 14 to 28 days and are documented in each manufacturer's prescribing information. A U-100 insulin syringe is appropriate because IU values map cleanly onto its 100-unit-per-mL scale.

Frequently asked questions

How does this growth hormone dose calculator work?

Enter the vial size in IU, the volume of bacteriostatic water you reconstituted with, and the target dose. The calculator returns the concentration in IU per millilitre, the draw volume in millilitres, and the equivalent reading on a U-100 insulin syringe. The math is exposed step-by-step on the /calculator page.

How many IU is 1 mg of growth hormone?

By the long-standing clinical convention, 1 mg of somatropin is approximately 3 IU. A 10 IU vial therefore contains about 3.33 mg of recombinant growth hormone, and a 6 IU vial contains roughly 2 mg.

What size vials does growth hormone come in?

Common somatropin vial sizes used in research and prescribing literature include 4 IU, 5 IU, 6 IU, 10 IU, 12 IU, 16 IU, 24 IU, and 36 IU. Brand-name pens (Genotropin, Humatrope, Norditropin, Saizen, Omnitrope) are sold in fixed IU presentations.

How much bacteriostatic water do I add to a growth hormone vial?

Manufacturer guidance varies by brand and vial size. Typical reconstitution volumes are 1 mL for a 6–12 IU vial or 1.5–2 mL for larger 16–36 IU vials. Always follow the volume specified on your specific vial's prescribing information.

How many U-100 units is 1 IU of growth hormone?

It depends on the reconstitution. A 10 IU vial in 1 mL of BAC water yields a 10 IU/mL concentration, so 1 IU equals 0.1 mL or 10 units on a U-100 insulin syringe. Using 2 mL of BAC water halves the concentration, doubling the syringe units per IU.

What is the difference between IU and mg dosing for growth hormone?

International Units measure biological activity, while milligrams measure mass. For somatropin specifically, 1 mg ≈ 3 IU. Prescribing labels and reconstitution guides typically use IU; some clinical literature and compounded research products use mg.