Blood Tests Before Peptides: The Complete Pre-Protocol Lab Guide

Blood Tests Before Peptides: The Complete Pre-Protocol Lab Guide

Last Updated: January 2026

You wouldn't start a road trip without checking your fuel gauge. So why would you start injecting peptides without knowing your baseline health markers?

Blood testing before peptide use isn't just about safety—it's about optimization.

Without baseline data, you can't measure whether your protocol is actually working.

You can't identify potential issues before they become problems. And you can't make informed adjustments to dosing or timing.

This guide covers exactly which tests to get, why they matter for different peptide categories, and where to order labs without the hassle of a doctor's appointment.

Why Blood Testing Matters Before Peptides

Peptides interact with your body's existing biochemistry. Their effects—and potential side effects—depend heavily on your current metabolic state.

Consider MK-677 (Ibutamoren): it raises growth hormone and IGF-1, but it also elevates fasting glucose.

If your blood sugar is already borderline high, this could push you into pre-diabetic territory. Without baseline testing, you'd never know until symptoms appeared.

Or take Retatrutide: it's a triple agonist affecting GLP-1, GIP, and glucagon receptors.

Understanding your baseline insulin sensitivity, thyroid function, and lipid markers helps you track the profound metabolic changes this peptide induces.

Even "safe" peptides like BPC-157 warrant baseline testing. Not because BPC-157 is dangerous, it has an excellent safety profile, but because healing peptides can mask underlying issues.

If your liver enzymes are elevated before you start, you'll want to address that root cause rather than just treating symptoms.

The Essential Baseline Panel (Everyone)

Regardless of which peptide you're using, these markers form your foundation:

Metabolic Health

• Fasting Glucose: Blood sugar control baseline. Critical for GH peptides.
• Fasting Insulin: Reveals insulin resistance before glucose goes high.
• HbA1c: 3-month average blood sugar. More stable than single glucose readings.
• HOMA-IR: Calculated from glucose and insulin. Best single marker for insulin sensitivity.

Liver Function

• ALT (Alanine Aminotransferase): Most specific liver enzyme. Should be under 30 U/L for optimal health.
• AST (Aspartate Aminotransferase): Liver and muscle marker. Elevated with intense training or liver stress.
• GGT (Gamma-Glutamyl Transferase): Sensitive to liver inflammation and alcohol. Often the first to rise.

Kidney Function

• BUN (Blood Urea Nitrogen): Protein metabolism and kidney filtration.
• Creatinine: Kidney filtration rate. Can be elevated in muscular individuals.
• eGFR: Estimated glomerular filtration rate. Best overall kidney function marker.

Lipid Panel

• Total Cholesterol: Less important than the breakdown below.
• LDL-C: "Bad" cholesterol. Context matters—particle size is more important.
• HDL-C: "Good" cholesterol. Higher is generally better.
• Triglycerides: Carb/sugar metabolism marker. Should be under 100 mg/dL.
• ApoB: The most important cardiovascular marker. Measures actual atherogenic particles.

Complete Blood Count (CBC)

• Red Blood Cells, Hemoglobin, Hematocrit: Oxygen-carrying capacity.
• White Blood Cells: Immune function baseline.
• Platelets: Clotting function.

Inflammatory Markers

• hs-CRP (High-Sensitivity C-Reactive Protein): Systemic inflammation. Should be under 1.0 mg/L.
• ESR (Erythrocyte Sedimentation Rate): Non-specific inflammation marker.

Peptide-Specific Testing

Healing Peptides: BPC-157 + TB-500

The Wolverine Complex (BPC-157 + TB-500 stack) has a favorable safety profile, but baseline testing still matters:

Additional markers to add:

• Iron Panel (Ferritin, TIBC, Serum Iron): TB-500 may affect blood vessel formation. Baseline iron status helps monitor this.
• VEGF (if available): Both peptides affect angiogenesis. Useful for tracking but not essential.

Focus on the baseline panel above. These peptides are generally well-tolerated, and the standard markers will catch any issues.

GH Secretagogues: MK-677, Ipamorelin, CJC-1295, Sermorelin

Growth hormone-releasing peptides require more comprehensive monitoring because they affect glucose metabolism, IGF-1 levels, and can influence tumor growth markers.

Critical additions for MK-677, Ipamorelin, and CJC-1295:

• IGF-1: Primary marker for GH activity. This is non-negotiable. Track before and during use.
• Fasting Glucose (repeated): MK-677 particularly can raise glucose. Test baseline and at 4-week intervals.
• Fasting Insulin: Pair with glucose to calculate HOMA-IR.
• Prolactin: Some GH peptides can affect prolactin. Get a baseline.
• Cortisol (AM): GH secretagogues interact with the HPA axis.

Why IGF-1 matters: If your IGF-1 doesn't increase on a GH secretagogue, either your peptide is underdosed, degraded, or your pituitary isn't responding. Without testing, you're flying blind.

Metabolic Peptides: Retatrutide, Tirzepatide, Semaglutide

Retatrutide and similar GLP-1 agonists cause profound metabolic changes. Comprehensive baseline testing is essential:

Critical additions:

• Full Thyroid Panel: TSH, Free T3, Free T4, Reverse T3. These peptides affect thyroid function.
• Leptin: Satiety hormone. Tracks metabolic adaptation.
• Adiponectin (if available): Insulin sensitivity marker from fat tissue.
• Uric Acid: Rapid weight loss can elevate uric acid. Baseline helps monitor gout risk.
• Vitamin B12: GLP-1 agonists can reduce B12 absorption over time.
• Electrolytes (Sodium, Potassium, Magnesium): Important with reduced food intake.

Anti-Aging & Longevity: MOTS-C, Epitalon, GHK-Cu

For longevity-focused peptides, broader biomarker panels help track systemic effects:

Consider adding:

• Homocysteine: Cardiovascular and methylation marker.
• Vitamin D (25-OH): Foundational health marker.
• Omega-3 Index: Inflammation and cell membrane health.
• Complete Hormone Panel: Testosterone, estradiol, DHEA-S, cortisol.

Where to Get Tested: Best Direct-to-Consumer Options

You don't need a doctor's appointment or insurance to get comprehensive blood testing. These services let you order labs directly:

1. Marek Diagnostics

Best for: Peptide users and serious biohackers
Why it's good: Founded by people in the optimization community. Offers panels specifically designed for hormone optimization and peptide monitoring. 85-100+ marker panels available.
Cost: $200-500 for comprehensive panels
Lab Partner: Quest Diagnostics
Turnaround: 3-7 days

2. Ulta Lab Tests

Best for: Budget-conscious testing with maximum coverage
Why it's good: Up to 90% off retail pricing. Huge selection of individual tests and panels. Great for building custom panels.
Cost: $50-300 depending on panel
Lab Partner: Quest Diagnostics
Turnaround: 2-5 days

3. Life Extension

Best for: Longevity-focused users who also want supplement guidance
Why it's good: Established company with 40+ years in longevity research. Includes free consultations with Wellness Specialists to interpret results.
Cost: $75-400 depending on panel
Lab Partner: LabCorp
Turnaround: 3-5 days

4. InsideTracker

Best for: Athletes wanting ongoing optimization tracking
Why it's good: AI-powered analysis with personalized recommendations. Tracks biological age. Best interface for monitoring trends over time.
Cost: $200-600 depending on plan
Lab Partner: Quest Diagnostics
Turnaround: 5-7 days

5. Quest Health (Direct)

Best for: Those who want a trusted national lab brand
Why it's good: 2000+ locations. Direct ordering from Quest Diagnostics. Includes optional physician consultation for results.
Cost: $50-300 depending on tests
Turnaround: 1-3 days

6. Personalabs

Best for: Wide test variety and telehealth follow-up
Why it's good: Over 400 tests available. Optional telehealth appointments to discuss results. Good balance of price and service.
Cost: $50-250 depending on panel
Lab Partner: LabCorp
Turnaround: 2-5 days

Step-by-Step: How to Order Your Labs

1. Choose your testing service based on budget, markers needed, and location convenience.
2. Select your panel. For first-time peptide users, choose a comprehensive panel ($150-300) rather than piecing together individual tests.
3. Complete checkout. You'll receive a requisition form via email within 24 hours.
4. Schedule your blood draw. Most services let you schedule online. Walk-ins are usually available.
5. Prepare properly:
   • Fast 10-12 hours (water okay)
   • Avoid alcohol 48 hours before
   • Schedule morning draws for accurate hormone readings
   • Avoid intense exercise 24 hours before
6. Get your blood drawn. Takes 5-10 minutes.
7. Review results when they arrive (2-7 days). Save them for comparison.

Interpreting Your Results: Optimal vs. "Normal"

Lab reference ranges are based on population averages—including sick people. "Normal" doesn't mean optimal.

Here are target ranges for key markers if you're pursuing optimization:

When to Retest

Baseline testing is just the start. Here's a recommended schedule:

• Baseline: Before starting any peptide protocol
• Week 4-6: First follow-up. Check for early changes, especially glucose and liver enzymes.
• Week 12: Comprehensive retest. Compare all markers to baseline.
• Quarterly: Ongoing monitoring during extended protocols.
• Post-protocol: 4-6 weeks after stopping to confirm return to baseline.

For GH secretagogues like MK-677, monitor glucose and IGF-1 more frequently—every 4 weeks initially.

Red Flags: When to Stop and Reassess

Stop your peptide protocol and consult a healthcare provider if you see:

• Liver enzymes (ALT/AST) rising above 2x upper limit
• Fasting glucose consistently above 100 mg/dL
• IGF-1 above 350 ng/mL (potential long-term risks)
• Significant kidney function decline (eGFR dropping)
• New or worsening symptoms that correlate with lab changes

The Bottom Line

Blood testing before peptides isn't optional, it's the difference between informed biohacking and guesswork.

At minimum, every peptide user should have:

• Complete metabolic panel (CMP)
• Complete blood count (CBC)
• Lipid panel with ApoB
• Fasting insulin and HbA1c
• Liver enzymes (ALT, AST, GGT)

Add IGF-1 for GH peptides, thyroid panel for metabolic peptides, and inflammatory markers if budget allows.

Total cost for comprehensive baseline testing: $150-400 through direct-to-consumer services. That's a small investment for the peace of mind and optimization data you'll get in return.

Once you have your baseline, you're ready to start your protocol.

Check out our guides on the Wolverine Complex (BPC-157 + TB-500), Retatrutide, or how to properly reconstitute your peptides.