HGH Kits, Pens and Secretagogues Compared

📅 June 17, 2026 ⏱️ 3 min read ✍️ Team TPS

“HGH” covers three quite different things in the UK. Somatropin kits, pre-filled pens, and secretagogues that make your body release its own. They are not interchangeable, and the price gaps between them make more sense once you know which is which.

1. Somatropin kits

Recombinant human growth hormone (rDNA origin, 191 amino acid) supplied as lyophilised vials with bacteriostatic water. This is actual growth hormone, you are adding the hormone itself, not prompting its release.

Kits are the traditional format: typically 10 vials of 10IU. They need reconstitution, careful storage, and dose calculation in IU. Stocked in the growth hormone range.

2. Pre-filled HGH pens

The same recombinant somatropin, already in solution in a sealed pen. No reconstitution and no bacteriostatic water, you dial units and dispense. SerenQ HGH 100iu and SerenQ HGH 30iu both sit in this category.

The compound is identical to a kit. What you pay for is the handling: no mixing step, no dilution decision, and a dial that reads the same every time.

3. Secretagogues, a different mechanism entirely

Ipamorelin, CJC-1295, tesamorelin and MK-677 are not growth hormone. They act on the pituitary to increase your own GH release, which means the effect is pulsatile and self-limiting rather than a fixed exogenous dose.

That distinction matters. Secretagogues work with an existing feedback loop; exogenous somatropin overrides it. They are generally cheaper, generally milder, and behave differently over time. See the HGH analogues and secretagogues range.

Reading IU vs mg vs units

This is where most confusion happens. Somatropin is measured in IU. Peptide secretagogues are measured in mg or mcg. A pen dial is measured in units, which are neither: a unit is a volume on the dial, and what it delivers depends on that pen’s concentration.

On the SerenQ HGH pens, 10 units equals 1 IU. On a peptide pen, the same 10 units delivers a completely different amount of a different thing. Always read the dial graduation on the specific product page rather than carrying a number across from another pen.

Which format for which situation

Kits, lowest cost per IU, most flexibility on concentration, most handling steps.

Pens, same hormone, no reconstitution, consistent dosing, higher cost per IU.

Secretagogues, different mechanism, generally cheaper, works with your own production rather than replacing it. A reasonable starting point if you have not run GH before.

Supplied for research purposes only. This article is informational and is not medical advice.