Sermorelin and IGF-1: What Your Bloodwork Tells Us

Disclaimer: Compounded sermorelin is prepared by a licensed 503A compounding pharmacy and has not been reviewed or approved by the FDA. This article is for educational purposes only, is not medical advice, and does not establish a provider-patient relationship.

When a patient asks me whether sermorelin is working, my answer is rarely based on how they feel alone. Feelings matter, but they are subjective and they lag. The objective answer comes from one blood marker: IGF-1. Why we watch that instead of growth hormone itself tells you most of what you need to know about monitoring this therapy.

Why We Do Not Measure Growth Hormone Directly

The intuitive assumption is that if sermorelin stimulates growth hormone, we should measure growth hormone to see if it is working. In practice that does not work, and the reason is physiological.

Growth hormone is secreted in brief pulses that vary dramatically across the day, with most release concentrated during deep sleep.[1] A single blood draw might catch a peak or a trough and tell you almost nothing about overall status. Measuring GH from one blood sample is like judging a city’s traffic from a single photograph taken at a random moment.

IGF-1, insulin-like growth factor 1, solves this problem. GH stimulates the liver to produce IGF-1, and IGF-1 remains stable in the bloodstream over a far longer window, reflecting cumulative growth hormone exposure over the preceding day or two rather than a single moment.[2] It is stable, reproducible, and it is also the molecule that mediates most of growth hormone’s tissue-level effects. That makes it both the practical measurement and the clinically meaningful one.

What the Research Shows About Sermorelin and IGF-1

The relationship between sermorelin and IGF-1 is well documented. In a frequently cited study, Corpas and colleagues gave a growth hormone-releasing hormone analog (the same 29-amino-acid fragment that sermorelin is) to healthy older men twice daily for two weeks. Treatment raised growth hormone and IGF-1 in a dose-related fashion, and at the higher dose brought the older men’s levels up to the range seen in younger men.[3]

This is the mechanism that matters clinically: sermorelin does not introduce growth hormone from outside the body. It stimulates the pituitary to release more of its own, and the downstream rise in IGF-1 is what we track to confirm the pathway is responding.[4]

How We Use the Number

Before starting therapy, our practice establishes a baseline IGF-1. This is essential. Without knowing where you started, a follow-up number is difficult to interpret. Baseline testing before initiating hormone optimization is standard clinical practice for exactly this reason.[2]

After a patient has been on therapy for a period, we recheck IGF-1 and compare against an age-adjusted and sex-adjusted target range. The goal is not to push the number as high as possible. It is to bring IGF-1 into an optimal physiologic range for the individual, not above it. More is not better here, and a responsible protocol keeps the number within, not beyond, normal reference ranges.

When the Number Looks Good but the Patient Does Not

One of the more useful things IGF-1 monitoring tells us is when the problem is not sermorelin at all. If a patient’s IGF-1 has risen into the target range but they are not feeling the benefits they expected, the issue is usually downstream of IGF-1 production. Common explanations include insufficient resistance exercise, which is the mechanical stimulus that IGF-1’s anabolic signal requires to translate into tissue change; inadequate protein or calories; poor sleep; or unrealistic timeline expectations, since some benefits take three to six months to become apparent.

This is why the bloodwork is a tool for the whole clinical picture, not a scorecard. A good IGF-1 number confirms the therapy is doing its job at the level of the pituitary and liver. Whether that translates into how you feel depends on the rest of your physiology and habits, and that is a conversation worth having with your provider.

The Takeaway

IGF-1 is the signal worth tracking. It is stable, it reflects cumulative growth hormone activity, and it lets us confirm the pathway is responding and adjust your protocol on data rather than guesswork. If you are considering sermorelin, expect a baseline draw before you start and a recheck after. Any program that does not monitor IGF-1 is flying blind.

For more on how sermorelin works and what to expect, see our overview at sermorelin therapy.

References

1. Van Cauter E, Plat L. Physiology of growth hormone secretion during sleep. J Pediatr. 1996;128(5 Pt 2):S32-S37. PubMed: 8627466

2. Molitch ME, Clemmons DR, Malozowski S, et al. Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96(6):1587-1609. PubMed: 21602453

3. Corpas E, Harman SM, Piñeyro MA, Roberson R, Blackman MR. Growth hormone (GH)-releasing hormone-(1-29) twice daily reverses the decreased GH and insulin-like growth factor-I levels in old men. J Clin Endocrinol Metab. 1992;75(2):530-535. PubMed: 1379256

4. Sinha DK, Balasubramanian A, Tatem AJ, et al. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Transl Androl Urol. 2020;9(Suppl 2):S149-S159. PubMed: 32257855

This article is for educational purposes only and does not constitute medical advice or establish a provider-patient relationship. Compounded medications have not been reviewed by the FDA and are not the same as commercially available FDA-approved products. Please consult a licensed provider.

Dr. Robert Chandler, DO, is a licensed provider at Precision Telemed. This article has been reviewed for clinical accuracy.