Peptide blood testing: what people track, and what it can tell them

A growing number of people run their own bloodwork while using peptides, some through a clinician and some through direct-to-consumer labs. There is no clinical guideline for monitoring most of these compounds, because most of them are not approved drugs and have little human trial data. So the markers people choose come from two places: general health screening, and what the published studies show a particular class of compound does. This page covers both, and the limits of each.

The markers, and why each is on the list

IGF-1 and the secretagogues

GH is released in pulses, so a single GH measurement is hard to interpret. IGF-1, which the liver makes in response to GH, is steadier, which is why it is the marker studies use. Two published trials show why people who use secretagogues track it.

CJC-1295, a long-acting GHRH analogue, was tested in two randomised, placebo-controlled ascending dose trials in healthy adults aged 21 to 61, published in 2006. After a single injection, mean IGF-1 rose 1.5 to 3-fold and stayed raised for 9 to 11 days. The estimated half-life was 5.8 to 8.1 days, and after repeated doses IGF-1 stayed above baseline for up to 28 days. The practical point: with a compound this long-acting, the number of days since the last dose changes the result, so it belongs on the requisition note.

MK-677 (ibutamoren) is often grouped with the peptides but is not one. It is an oral small molecule that mimics ghrelin. In a randomised trial of 65 healthy adults aged 60 to 81, published in 2008, 25 mg daily raised IGF-1 into the range of healthy young adults. Fasting glucose rose by an average of 0.3 mmol/L (5 mg/dL) and insulin sensitivity fell. LDL fell slightly, and the most frequent side effects were increased appetite, mild leg oedema and muscle pain. That glucose finding is why HbA1c and fasting glucose sit next to IGF-1 on most secretagogue panels.

Ipamorelin has far less published human data than either. FDA's list of bulk substances that may present significant safety risks includes ibutamoren and, for outsourcing facilities, ipamorelin. The CJC-1295, ipamorelin and MK-677 pages have the full evidence summaries.

Compounds with no lab marker

For many popular peptides there is no marker that shows whether the compound is doing anything. BPC-157 is the clearest example. A 2025 systematic review in orthopaedic sports medicine found 36 eligible studies, of which 35 were preclinical and one was clinical, and found no clinical safety data. A blood panel taken while using it can show general kidney, liver and blood count status. It cannot show an effect, because nobody has established what the effect would look like in blood. The same is true of TB-500 and most of the healing and longevity peptides.

The limits of what bloodwork shows

• A normal panel is not proof of safety. Most adverse effects people worry about do not appear in a CMP or CBC.
• A flagged value is not proof of harm. Reference intervals are conventionally built from the central 95% of results in healthy people, so 5% of healthy results fall outside them by design. Run 30 markers and something will often flag.
• Bloodwork does not test the vial. Purity, identity and contamination are properties of the product, not the person. The purity testing and certificate of analysis entries cover that side.
• One person is not a trial. A change in your own series can come from diet, training, sleep, illness, other medicines or chance. The study designs that separate those are described in how peptide research works.

Reading reference ranges

Every range on a report belongs to that laboratory and that method. IGF-1 ranges are also strongly age-specific, so the same number can be mid-range at 60 and low at 25. Compare a result with the range printed beside it, not one from another lab, and keep a marker at one lab where you can. The guide to reading a lab report goes through units, flags and why two labs disagree.

Timing a draw so it means something

• Same time of day, same fasting state. Glucose and triglycerides change after food. A morning fasting draw is the usual standard, and the comparison only works if every draw follows it.
• Same point in the dosing cycle. Write down the day since the last dose. For long-acting compounds it changes the answer.
• Avoid a hard training session the day before. Strenuous exercise can raise muscle-derived markers, including creatinine, AST and ALT, and make a normal liver look stressed.
• Get a baseline first. A value on day 60 with nothing to compare it to tells you very little.

For GLP-1 drugs, where there is trial data on what moves, the GLP-1 blood work page has the numbers. None of this replaces a clinician reading the result with your history in front of them.

In Peptide AI, the dose log, titration steps, side effects and weight are free to log. Premium adds bloodwork: upload a lab PDF and the markers land on the same timeline as every dose, so a lipid panel at week 30 sits next to the step-up at week 17 rather than in a separate folder. The free GLP-1 tracker page has the detail, and the app is on the download page.