IGF-1: the number used to monitor sermorelin

What IGF-1 is

IGF-1 is a hormone that carries out many of growth hormone's effects. MedlinePlus describes the two working together to support normal bone and tissue growth, with growth hormone also helping to regulate metabolism. Most IGF-1 is produced by the liver after growth hormone signals it.

Sermorelin works one step further up the chain. It is a shortened form of growth hormone-releasing hormone (GHRH), the signal the brain uses to tell the pituitary gland to release growth hormone. So the expected sequence is sermorelin, then growth hormone, then IGF-1.

Why IGF-1 stands in for growth hormone

Growth hormone is released in pulses, with much of it at night, and levels swing with food and activity. A single growth hormone test can catch a peak or a trough and tell you very little. IGF-1 is far more stable from hour to hour, which is why MedlinePlus calls it a more reliable way to track growth hormone activity.

That makes IGF-1 the main lab marker for sermorelin. It is a measure of exposure: whether the growth hormone axis is being stimulated.

Age changes the range

IGF-1 is low in childhood, peaks during puberty and declines through adulthood. Lab reports usually compare your result with a range for your age, and sometimes your sex. A value near the lower part of the range at 55 is common and is not, by itself, a deficiency.

MedlinePlus notes that low IGF-1 in an adult may reflect normal age-related decline or another condition that needs further tests. High IGF-1 can signal acromegaly, usually caused by a pituitary tumor, which is one reason clinicians do not chase ever-higher numbers.

What a rise tells you, and what it does not

• A rise after starting suggests your pituitary is responding and that the medicine is being absorbed. That matters for a dissolving tablet, because how well sermorelin is absorbed through the mouth has not been established in published studies.
• No rise after an adequate period is useful information too, and a reason to reconsider whether sermorelin is worth continuing.
• IGF-1 does not measure benefit. Sleep, energy, body composition and mood do not reliably track the number, and benefits in healthy adults are not well proven.
• Higher is not better. Large population studies link higher IGF-1 with greater risk of some cancers, so the usual aim is a level that is reasonable for your age, not the top of the range.

Things that can move your result

Many everyday factors affect IGF-1 besides medicine: nutrition and recent calorie restriction, significant weight change, liver health, thyroid function, poorly controlled diabetes, illness and heavy alcohol use. Using the same lab and drawing at a similar time each time makes comparisons more meaningful.

If you are losing weight on a GLP-1 medicine, or have just changed your diet substantially, mention it, because reduced intake can lower IGF-1 independently of sermorelin.

When it is usually checked

• Before starting, to establish your baseline and screen for unexpected highs or lows.
• After you have been on a steady dose long enough for an effect to appear, typically some weeks to a few months.
• Periodically during treatment, and after any dose change.
• Sooner if you develop symptoms such as joint pain, swelling, numbness or tingling in the hands, or new headaches.

Sermorelin's regulatory status

Injectable sermorelin was once FDA-approved as Geref, for growth hormone deficiency in children and for testing pituitary function. It was discontinued in 2008, and in 2013 the FDA determined it had not been withdrawn for safety or effectiveness reasons. Today sermorelin is available only from compounding pharmacies.

Sermorelin ODT through HealifyMD is compounded by a licensed U.S. pharmacy. It is not FDA-approved, has not been reviewed by the FDA for safety, effectiveness or quality and is not equivalent to the former branded injection. It is from $199/month, confirmed at the eligibility review, with labs priced separately; our comprehensive lab panel is $199.