How to track an IGF-1 cycle with bloodwork

You're running Ipamorelin + CJC-1295. Or Tesamorelin. Or MK-677. The protocol is set, the doses are in, the schedule is consistent. The question every honest user eventually asks: "Is this actually working?" Subjective markers — sleep quality, recovery feel, body composition changes — are useful but slow and easy to misread. The fast, objective answer comes from a single number: your IGF-1 level measured before and during the cycle.

This post is the practical guide to using IGF-1 bloodwork to track your cycle: when to test, how to interpret the numbers, what to do with the results, and why most users get this wrong.

Why IGF-1 is the right marker

Growth hormone itself is hard to measure usefully. GH is released in pulses — short bursts mostly during sleep, with low baseline levels between pulses. A random GH measurement might catch a peak or a trough; neither tells you much about chronic exposure.

IGF-1 (insulin-like growth factor 1) is produced by the liver in response to GH stimulation and circulates at much more stable levels. A single IGF-1 measurement reflects the average GH exposure over the prior 24–48 hours. It's the canonical marker for assessing GH-axis activity in both clinical medicine and strength-peptide community use.

If your GH peptide is working, your IGF-1 rises. If your IGF-1 doesn't rise, the peptide isn't working — either because of vendor issues, dose timing, biological non-response, or expectations problems. See why some lifters do not respond to GH peptides.

For the broader monitoring frame see baseline labs before a cycle and IGF-1 testing.

The testing schedule

A practical schedule for a 12-week GH peptide cycle:

This is the rigorous version. The minimum-viable version: baseline + week 8 + 4 weeks post. The week 4 check is most useful for users new to GH peptides or new to a specific vendor.

How to order the test

Three pathways:

Through your physician. Best if you have a primary care doctor who knows about your peptide use (see should I tell my doctor I'm using peptides?). Order code: IGF-1, sometimes listed as "Somatomedin-C." Insurance coverage variable.

Direct-to-consumer labs. Quest Diagnostics, LabCorp, and several specialty services offer IGF-1 testing without a physician order in most states. Cost typically $50–150 out of pocket. Examples: Marek Health, Inside Tracker, Empower, and similar services.

Specialty hormone panels. If you want a more comprehensive picture, order a panel that includes IGF-1 alongside testosterone, estradiol, cortisol, etc. Often costs more but gives broader context.

For users running longer cycles or multiple peptides, the panel approach is usually worth the additional cost.

How to interpret the numbers

IGF-1 results come back as a number (typically ng/mL or μg/L — they're equivalent) plus an age-adjusted reference range. The reference range matters a lot — IGF-1 declines naturally with age.

Typical reference ranges by age:

These vary slightly between labs; always use the reference range printed on your specific report.

Interpreting your numbers:

• Baseline — where you sit naturally. Should fall within your age-adjusted reference range. If your baseline is already at the top of the range, GH peptides may push you out of normal — worth discussing with your physician.
• Cycle peak (typically week 8–12) — should be elevated 30–80% from baseline if the peptide is working at typical doses. So a baseline of 200 should peak somewhere 260–360 on a working cycle.
• Post-cycle (4 weeks off) — should return to or near baseline. Significantly elevated 4 weeks post suggests residual effect; significantly lower suggests cycle suppression.

What constitutes "working":

What to do with the data

If your week-4 IGF-1 didn't move:

• Verify timing (fasted, consistent dosing)
• Verify storage (refrigerated reconstituted vials)
• Consider switching vendor
• Consider dose adjustment

See the GH peptide non-responders post for the systematic diagnostic.

If your week-8 IGF-1 is too high (above reference range):

• Reduce dose 25–50%
• Re-test 4 weeks after reduction
• Some users tolerate elevated IGF-1 fine; others experience side effects (joint aches, water retention, headaches). Watch how you feel.

If your fasting glucose has drifted upward:

• Common with MK-677 and IGF-1 LR3, less common with Ipamorelin/CJC
• Reduce dose
• Address dietary factors (high-glycemic foods, late-night eating)
• Track for several months — drift can reverse

If your hematocrit is rising:

• Less common with GH peptides than with TRT
• Increase hydration
• Discuss with physician if approaching 53+

For broader cycle monitoring see cardiovascular markers on peptide cycles.

Timing the blood draw

A few practical points:

Fasted vs fed. IGF-1 is reasonably stable across the day — fasting isn't strictly necessary, but fasted draws are standard for consistency. If you're also checking glucose, fasted is required.

Time of day. IGF-1 doesn't have a strong circadian rhythm. Morning draws are conventional but afternoon is fine.

Recent training. Heavy exercise the day before can transiently elevate IGF-1. For most users this doesn't matter; for users trying to measure precisely, schedule the draw on a rest day.

Recent injection. For accurate cycle assessment, draw at least 12 hours after the most recent peptide injection. The peptide pulse itself doesn't change the day-of IGF-1 measurement much (IGF-1 reflects multi-day exposure), but consistency helps comparison.

Avoid drawing within 24 hours of a sick day. Acute illness affects IGF-1.

What about other markers?

A few markers sometimes worth tracking alongside IGF-1:

For most users on Ipamorelin/CJC stacks, IGF-1 + fasting glucose is sufficient. Add the others if you're running more aggressive or longer-duration protocols.

Common mistakes

A few patterns to avoid:

Skipping the baseline. Without a baseline, you can't tell if the cycle changed anything. Insist on baseline IGF-1 before starting.

Only one mid-cycle check. Single data points are noisy. Two checks (week 4 + week 8) plus baseline and post-cycle gives a real picture.

Misreading age-adjusted ranges. A 50-year-old with IGF-1 of 250 is high; a 25-year-old with the same number is normal. The reference range matters.

Chasing the number. Some users see "good response" and immediately increase the dose. Higher IGF-1 isn't automatically better — it's a marker of GH-axis activity, not a goal. Push too high and side effects increase faster than benefits.

Ignoring the trend. Single results are less informative than trends over time. Track over multiple cycles to understand your individual response patterns.

The bottom line

IGF-1 bloodwork is the single most useful tool for understanding whether your GH peptide cycle is working. Baseline + week 8 + post-cycle is the minimum-viable version; baseline + week 4 + week 8 + cycle end + post-cycle is the rigorous version. The numbers tell you whether the peptide is reaching its target, whether your dose is appropriate, and whether your protocol is sustainable long-term.

Without the data, you're guessing. With the data, you can adjust based on real signal rather than subjective interpretation.

Related reading

• IGF-1 testing
• Baseline labs before a cycle
• Why some lifters do not respond to GH peptides
• IGF-1 levels and aging data
• Cardiovascular markers on a peptide cycle