TL;DR
- 1.IGF-1 confirms the GH axis responded. It tells you nothing about whether your insulin sensitivity dropped, your inflammation shifted, or your red blood cell count crept up. You need six more numbers.
- 2.IGFBP-3 holds roughly 80% of your IGF-1 inactive. When IGFBP-3 is low, your free IGF-1 tissue exposure is higher than your lab result shows. The molar ratio catches this. IGF-1 alone does not.
- 3.Fasting glucose rising on MK-677 is a documented RCT finding from a 2-year trial. Fasting insulin catches the problem earlier than glucose alone. Know your baseline before you start any protocol.
- 4.hsCRP is the marker that tells you whether a healing peptide protocol is actually reducing inflammation. No other standard lab value does that.
- 5.Draw all 7 at baseline before you start, then again at 6 weeks. The comparison between those two draws tells you what the peptide is actually doing to your biology.
Most peptide bloodwork guides track one number: IGF-1. That number tells you your GH axis responded. It tells you nothing about whether your insulin sensitivity dropped, your inflammation went the wrong direction, or your red blood cell count quietly shifted upward. One marker reads one pathway. Peptide protocols touch at least seven.
The gap between what a protocol does and what a single-marker panel shows is where protocols go quietly wrong for months. Running ipamorelin, CJC-1295, MK-677, BPC-157, or any combination means your protocol is touching your metabolism, your inflammation pathways, and your hormonal environment simultaneously. You need a fuller picture to know whether it is going well.
Here are the 7 lab values that give the complete story: what each one measures, how it shifts on specific peptide protocols, what threshold should prompt action, and when to draw it.
Sensitivity of the IGF-1:IGFBP-3 molar ratio for detecting GH-axis dysfunction, versus 42.2% for IGF-1 alone on the same patients. A 2023 study in the Journal of Clinical Endocrinology and Metabolism found the ratio caught nearly twice as many abnormal responses that a standard IGF-1 draw would have missed entirely.
The reason that gap exists: IGFBP-3 binds roughly 80% of circulating IGF-1 and holds it inactive. If your IGFBP-3 is low, a normal-looking IGF-1 reading still means more free IGF-1 is reaching your tissues than the number implies. You cannot know that without testing both.
Plain English: Think of IGF-1 as a car speedometer. It tells you how fast the engine is turning over. But it cannot tell you whether the fuel is low, the coolant is overheating, or the oil pressure has dropped. These 7 lab values are the full instrument panel. The speedometer alone does not tell you if the car is safe to drive.
Why Every Peptide Bloodwork Guide Stops Too Soon
GH secretagogue research uses IGF-1 as the primary endpoint because it is a stable, reproducible surrogate for GH pulsatility. That makes it the right endpoint for a trial. It does not make it a complete safety and efficacy panel for a 12-week self-directed protocol.
What a solo IGF-1 draw misses:
- Whether IGFBP-3 is proportionally low, meaning free IGF-1 tissue exposure is higher than the total number shows
- Whether fasting glucose crept up by 5 to 10 mg/dL (a documented MK-677 effect that accumulates over weeks)
- Whether systemic inflammation actually fell (the stated goal of most healing peptide protocols)
- Whether red blood cell mass is shifting at sustained high IGF-1 levels
- Whether testosterone moved indirectly via the GH and IGF-1 relationship with LH sensitivity
None of these require exotic tests. They come from a standard metabolic panel, CBC, and one hormone add-on. Most can be drawn from a single tube. The full 7-marker panel costs under $200 at direct-to-consumer labs and takes 15 minutes at any draw site.
Which 7 Numbers Belong on Every Peptide Protocol?
1. IGF-1: The Primary GH Axis Signal
IGF-1 is the foundation and you do need it. Produced primarily in the liver in response to GH pulses, IGF-1 remains stable in circulation for 12 to 24 hours, unlike GH itself (which clears in minutes). That stability makes it the practical proxy for cumulative GH axis activity across days and weeks.
A 2006 study in the Journal of Clinical Endocrinology and Metabolism (Teichman et al.) found CJC-1295 raised IGF-1 by 1.5 to 3 times above baseline in healthy adults, with elevations persisting up to 28 days on repeat dosing. MK-677 at 25 mg daily produced a sustained 1.5-fold rise over 12 months with no sign of receptor desensitization, confirmed in a 2-year randomized trial published in the Annals of Internal Medicine (Nass et al., 2008).
Target the upper half of your age-adjusted reference range, not above it. Commonly cited ranges from AACE clinical guidelines and major lab reference populations: 17 to 24 years, approximately 180 to 780 ng/mL; 25 to 39 years, approximately 114 to 400 ng/mL; 40 to 54 years, approximately 90 to 360 ng/mL; above 54 years, approximately 70 to 290 ng/mL. Assays vary by 10 to 15% between labs; use your specific lab range as the reference. For the action protocol when IGF-1 reads too high, see 9 signs your IGF-1 is too high.
2. IGFBP-3: The Number That Corrects IGF-1
IGFBP-3 is the correction factor that makes IGF-1 interpretable. It is the primary transport protein for IGF-1 in circulation. High IGFBP-3 buffers IGF-1 tissue exposure; low IGFBP-3 amplifies it. The molar ratio (IGF-1 in nmol/L divided by IGFBP-3 in nmol/L) tells you what fraction of IGF-1 is likely free and bioactive at the tissue level.
A 2019 study in the Journal of Clinical Research in Pediatric Endocrinology (Poyrazoğlu et al.) confirmed that IGFBP-3 follows an initial linear rise on GH therapy, then plateaus while IGF-1 continues climbing at higher doses. That divergence is where the elevated molar ratio shows up, and where the risk signal concentrates. The authors concluded that the ratio is a more sensitive safety monitor than IGF-1 alone because it reflects actual free hormone exposure.
For a detailed walkthrough of how to calculate and interpret the ratio from your lab report, see the IGF-1 to IGFBP-3 ratio guide. Practically: if your IGF-1 is in range but your IGFBP-3 sits in the bottom quartile, free IGF-1 is hitting tissue at higher levels than the absolute value suggests. The IGFBP3 rs2854744 variant (C/C genotype) is the most common genetic reason for chronically low IGFBP-3 across all peptide protocol types.
3. Fasting Glucose: The Metabolic Safety Gate
Fasting glucose is the most important metabolic safety marker for GH secretagogue protocols. IGF-1 and GH both oppose insulin action. At the doses peptide protocols produce, this effect is typically modest. But it is real, it is cumulative, and it is dose-dependent.
The Nass et al. 2-year randomized trial (Annals of Internal Medicine, 2008) found MK-677 at 25 mg daily raised fasting glucose, HbA1c, and cortisol and decreased insulin sensitivity over 12 months. In participants who remained in the trial to 24 months, the fasting glucose elevation partially attenuated. That attenuation is reassuring but not universal and does not eliminate the need to monitor from the start.
Average fasting glucose rise on MK-677 at 25 mg daily over 12 months, from the Nass et al. randomized trial. Not alarming in healthy adults who start below 90 mg/dL. A real problem for anyone starting near 95 mg/dL, where a 5-point shift crosses the prediabetes threshold at 100 mg/dL.
For pulsatile injectable protocols (ipamorelin, CJC-1295, sermorelin), the glucose effect is considerably smaller because GH pulses are physiological in amplitude and brief, not continuous across 24 hours. MK-677's sustained GH elevation is the pharmacological reason its metabolic signal is stronger than injectables at equivalent dosing. For the complete picture of what MK-677 does to metabolic markers across 24 months, see the MK-677 long-term results breakdown.
Action threshold: if fasting glucose rises above 100 mg/dL from a sub-100 baseline, add fasting insulin to your next draw. If glucose exceeds 110 mg/dL, pause the protocol and retest before continuing.
4. Fasting Insulin: The Earlier Warning
Fasting insulin catches insulin resistance before fasting glucose does. The standard progression is: insulin rises first as the pancreas compensates for reduced sensitivity, then glucose rises later when compensation fails. By the time fasting glucose exceeds 100 mg/dL, insulin resistance has often been building for months.
Normal fasting insulin is typically below 10 to 15 mIU/L depending on the lab. Values above 20 mIU/L in a fasted state suggest meaningful insulin resistance even when glucose is still in range. You can also calculate HOMA-IR (Homeostatic Model Assessment for Insulin Resistance) from the two raw numbers: fasting glucose in mg/dL multiplied by fasting insulin in mIU/L, divided by 405. A result above 1.9 is considered insulin-resistant; above 2.9 is clinically significant in most reference populations.
Fasting insulin requires a separate add-on from most labs and is not included in the standard comprehensive metabolic panel. It costs between $15 and $30 at direct-to-consumer pricing and is worth adding. Action thresholds: if HOMA-IR climbs above 2.0 from a baseline below 1.5, reduce the peptide dose and increase resistance training frequency. If HOMA-IR exceeds 2.9, hold the protocol entirely until it normalizes.
5. hsCRP: The Inflammation Check
hsCRP (high-sensitivity C-reactive protein) is the only standard bloodwork marker that directly tracks the primary goal of healing peptide protocols. BPC-157, TB-500, GLP-2, and thymosin-family peptides all claim anti-inflammatory benefits. hsCRP tells you whether any of that is actually measurable in your blood.
CRP is produced by the liver in response to systemic inflammation signals, primarily IL-6 and TNF-alpha. The high-sensitivity version detects clinically relevant low-grade inflammation that the standard CRP test misses. A 2021 study in the Journal of the Endocrine Society (PMC8090618) found that peak GH response to GHRP-2 stimulation was significantly and inversely correlated with hsCRP (r = negative 0.48, p below 0.001) in 81 adults with pituitary pathology: more GH response, lower inflammation. A 2025 study in Hormone Research (PMC11900236) found that maintaining IGF-1 in the upper-normal range on long-term GH therapy was associated with lower hsCRP compared to subtherapeutic dosing. The directionality supports using hsCRP as a monitoring marker on GH axis and healing peptide protocols.
Reference ranges: below 1.0 mg/L is low cardiovascular risk; 1.0 to 3.0 mg/L is moderate; above 3.0 mg/L is elevated. A meaningful protocol improvement is a drop of at least 0.5 mg/L from a baseline above 1.5 mg/L over 8 to 12 weeks. If hsCRP rises on a protocol that is supposed to reduce inflammation, rule out acute infection, overtraining, or a dietary inflammatory event in the week before the draw before attributing the rise to the peptide.
6. CBC: Hematocrit and Red Blood Cell Count
IGF-1 has documented erythropoietic effects. It stimulates red blood cell production via erythropoietin amplification. A 1997 study in Clinical Endocrinology (Götherström et al.) found that in adults with GH deficiency treated with replacement therapy, RBC count rose by approximately 0.36 per 10 to the 12th per liter alongside rising IGF-1 and IGFBP-3. The effect in healthy adults using secretagogues at physiological doses is likely smaller, but it is worth monitoring because the signal accumulates over time and is asymptomatic until hematocrit is already elevated.
The relevant markers from a standard CBC: hematocrit (normal 36 to 48% in women, 41 to 53% in men) and red blood cell count (normal 3.9 to 5.2 million cells per uL in women, 4.5 to 5.9 million cells per uL in men). A hematocrit above the sex-specific upper limit on a peptide protocol is a signal to reduce dose and recheck in 4 weeks, not to continue at the same dose.
For users combining GH secretagogues with testosterone replacement therapy, the CBC is especially critical. Testosterone has independent erythropoietic effects. The two combined can push hematocrit into a range that meaningfully increases whole-blood viscosity and cardiovascular risk. Monitor both as variables.
7. Total Testosterone: The Hormonal Baseline
Testosterone belongs on your baseline panel for two practical reasons. First, it is the hormone most commonly co-managed alongside peptide protocols, whether through TRT or natural optimization. Knowing where it sits before you start tells you whether changes in energy, libido, or body composition are coming from the peptide, from hormonal status, or from both.
Second, there is a documented interaction between GH secretagogues and the hypothalamic-pituitary-gonadal axis in specific populations. A 2017 study in the American Journal of Men's Health (Sigalos and Pastuszak) found that hypogonadal men on TRT who added a GH secretagogue combination saw total testosterone rise from 159.5 to 239.0 ng/mL alongside a significant rise in IGF-1. The effect appears to reflect IGF-1-potentiated LH sensitivity in Leydig cells at supraphysiological IGF-1 concentrations.
Sermorelin studies in older men (Corpas et al., Vittone et al., Khorram et al., reviewed in Translational Andrology and Urology, 2020) found no statistically significant testosterone change without TRT co-administration. For most solo secretagogue users, the testosterone draw is about establishing a reference point for interpretation, not expecting a major direct effect from the peptide.
IGF-1 measurement alone had 42.2% sensitivity for detecting growth hormone axis dysfunction. The IGF-1 to IGFBP-3 molar ratio achieved 87.5% sensitivity on the same patients, catching nearly twice as many abnormal responses that a standard IGF-1 draw would have missed entirely.
Journal of Clinical Endocrinology and Metabolism, 2023
| Marker | What It Measures | Action Threshold | Relevant Protocol |
|---|---|---|---|
| IGF-1 | GH axis response | Above age-adjusted upper limit on 2 consecutive draws | All GH secretagogues |
| IGFBP-3 | Free IGF-1 correction | Molar ratio skewed high with in-range total IGF-1 | All GH secretagogues |
| Fasting glucose | Metabolic safety gate | Above 100 mg/dL rising from sub-100 baseline | MK-677 primarily; all GH secretagogues |
| Fasting insulin | Early insulin resistance signal | Above 15 mIU/L; HOMA-IR above 2.0 | MK-677; longer running protocols |
| hsCRP | Systemic inflammation | Rising above 3.0 mg/L; no drop from elevated baseline | BPC-157, TB-500, healing peptides |
| CBC (Hct, RBC) | Red blood cell mass | Hematocrit above sex-specific upper limit | MK-677; GH secretagogues plus TRT |
| Total testosterone | Hormonal baseline and reference | More than 30% rise from personal baseline without TRT | All protocols (baseline reference) |
What to Do When a Number Comes Back Wrong
Most bloodwork guides end at "consult your physician." That is correct advice. It is also useless for someone who does not have a physician managing their off-label protocol. Here is the decision framework for the most common abnormal findings.
Hold the next dose. Draw trough IGF-1 twelve to twenty-four hours after last injection. If still elevated, reduce dose by 15 to 20%. Retest in 4 weeks. If normalized, stay at the lower dose. Return to original dose only after two clean consecutive draws at the lower level.
Add fasting insulin to your next draw. Calculate HOMA-IR. If HOMA-IR is below 1.9 and glucose is below 110, reduce the dose and increase resistance training frequency. If HOMA-IR exceeds 2.0 or glucose exceeds 110, pause the protocol entirely and retest in 4 weeks before resuming.
Rule out acute infection, overtraining, and dietary inflammatory events in the week before the draw. If none apply, add a 2-week washout and retest. A confirmed rise with no external cause suggests the protocol is not addressing the upstream inflammation driver.
Pause the protocol immediately. Increase hydration. Retest CBC in 3 weeks. If normalized, resume at a lower dose with monthly CBC monitoring. If still elevated, do not resume without clinical evaluation. In combined GH secretagogue plus TRT users, consider reducing the TRT dose as the first variable.
When Should You Draw Each Test?
Timing matters more than most guides acknowledge. IGF-1 is stable enough to draw at any time of day, but draw timing relative to your last dose changes whether you are reading a trough or a peak. For the complete timing protocol organized by peptide class, see the IGF-1 blood test timing guide.
The short version for injectable GH peptides (ipamorelin, CJC-1295, sermorelin): draw at least 12 hours after your last injection. This lets GH return toward baseline while IGF-1 remains stable. For MK-677 (oral, 5 to 6 hour half-life): draw in the morning before your dose, roughly 18 to 24 hours after the prior day's dose.
Fasting markers (glucose and insulin) require a minimum 8-hour fast from food. Aim for 10 to 12 hours for cleaner insulin readings. Water is fine during the fast. Coffee is not. Avoid intense exercise in the 24 hours before the draw; post-exercise CRP elevation can persist into the following morning and skew the hsCRP reading.
CBC has no fasting or timing requirement relative to dose. Draw it from the same tube as your IGF-1 panel to avoid duplicate collection fees. Total testosterone should be drawn in the morning (7 to 10 AM) when it naturally peaks, at least on the first draw to establish a consistent baseline for comparison.
How to Order These Tests Without a Doctor's Order
Direct-to-consumer lab ordering is legal in most US states. Services including Ulta Lab Tests, Walk-In Lab, Request A Test, and LabCorp patient direct allow you to order tests, pay directly, and receive results without a physician order. You then visit a local draw site (LabCorp or Quest Diagnostics network) and results arrive within 24 to 72 hours.
The specific panel to order: IGF-1 (insulin-like growth factor 1), IGFBP-3 (insulin-like growth factor binding protein 3), comprehensive metabolic panel (includes fasting glucose and liver enzymes), fasting insulin as a separate add-on, hsCRP high sensitivity, CBC with differential, and total testosterone. Most draw from a single tube at one sitting. Bundle them if the service allows to eliminate duplicate collection fees.
Estimated pricing at direct-to-consumer labs: IGF-1 ($25 to $65), IGFBP-3 ($30 to $50), fasting insulin ($15 to $30), hsCRP high sensitivity ($15 to $25), CBC ($10 to $20), testosterone ($20 to $45), comprehensive metabolic panel ($15 to $30). Bundled panels covering most of these run between $80 and $200 depending on the service. The full 7-marker panel typically costs less than one month of most peptide protocols.
For ipamorelin protocols specifically: draw the complete 7-marker baseline before your first injection, then recheck the full panel at 6 weeks. If all markers are in range at 6 weeks, move to quarterly monitoring for the duration of the protocol.
Seven numbers beat one. IGF-1 confirms the GH axis responded. IGFBP-3 corrects it. Fasting glucose and insulin catch the metabolic signal before it becomes a problem. hsCRP tells you whether healing peptides are actually moving inflammation in the right direction. CBC spots hematocrit drift before it becomes a cardiovascular risk. Testosterone gives you a hormonal reference point for interpretation. Together, these 7 values take 15 minutes to draw and cost less than one month of most peptide protocols.
Before you run any panel, get your genetic baseline at PeptidesDNA. Your GHR genotype, IGFBP3 variant, and CYP metabolizer status all change which of these 7 numbers is most likely to shift on your specific protocol and by how much. Or order the saliva kit and we will send you a personalized responder report before you draw a single tube.
Your DNA shapes how you respond to the peptides discussed above.
A personalized report scores 25+ peptides against your unique genetic profile — including the ones covered in this article.
Frequently asked questions
What blood tests should I get before starting a peptide protocol?
Before starting any GH secretagogue, draw baseline IGF-1, IGFBP-3, fasting glucose, fasting insulin, hsCRP, CBC with differential, and total testosterone. This baseline panel is what you compare your 6-week on-protocol draw against. Starting without a baseline means you cannot tell what the peptide changed versus what was already there before you began.
How long should I fast before peptide bloodwork?
Fast 10 to 12 hours for fasting glucose and fasting insulin. Longer fasts skew insulin readings downward and make it harder to compare results between draws. CBC and hsCRP have no fasting requirement. IGF-1 is stable regardless of fasting state. Plan your draw for the morning, fast from the night before, and skip coffee as well as food.
When should I draw IGF-1 relative to my peptide dose?
For injectable GH peptides including ipamorelin, CJC-1295, and sermorelin, draw at least 12 hours after your last injection. This lets GH return toward baseline while IGF-1 stays stable. For MK-677, draw in the morning before your daily dose, roughly 18 to 24 hours after the prior dose. The goal is a stable steady-state IGF-1 reading, not a transient peak.
My fasting glucose went up on MK-677. Is this serious?
A small rise of 3 to 7 mg/dL is a documented finding from the 2-year Nass et al. trial and is expected at 25 mg daily. Whether it matters depends on your baseline. If you started below 90 mg/dL and are now at 95, watch it closely but do not panic. If you started at 95 and are now at 105, you have crossed the prediabetes threshold and the protocol needs dose reduction or a pause. Add fasting insulin to your next draw to calculate HOMA-IR before making a final decision.
Does BPC-157 show up on any blood tests?
BPC-157 itself does not appear on standard bloodwork panels; there is no commercial assay for the peptide or its metabolites in clinical use. What bloodwork can tell you is whether the protocol is working: hsCRP should fall if inflammation is the target, and liver enzymes (ALT and AST from the comprehensive metabolic panel) can confirm BPC-157 is not causing hepatic stress. The peptide effects are measured through downstream biomarkers, not the peptide directly.
Can I order peptide bloodwork without a doctor?
Yes, in most US states. Direct-to-consumer lab services including Ulta Lab Tests, Walk-In Lab, and Request A Test allow you to order IGF-1, IGFBP-3, fasting insulin, hsCRP, and CBC without a physician order. You pay directly and receive results digitally. California and New York restrict certain direct-to-consumer tests; check your state before ordering. The blood draw itself happens at a standard LabCorp or Quest Diagnostics site.
How often should I retest while on a peptide protocol?
Draw the full 7-marker panel at baseline before starting, then again at 6 weeks on protocol, then every 3 months for running protocols. If any marker comes back abnormal at 6 weeks, retest that specific marker every 4 weeks until it normalizes, then return to quarterly monitoring. For protocols running longer than 6 months, add a dedicated quarterly testosterone and CBC check even if all earlier draws were clean.
This article is for informational and educational purposes only. It is not medical advice and does not diagnose, treat, cure, or prevent any disease. Consult a qualified healthcare professional before starting any peptide protocol. Individual results vary.