Bloodwork and monitoring: what to test before, during, and after

Why monitor

Two reasons. First, baseline labs tell you whether you should be running the protocol at all — uncontrolled hypertension, occult thyroid disease, or borderline kidney function will all change the calculus. Second, follow-up labs tell you whether the protocol is doing what you think it is doing, and whether it is doing something else you did not invite.

Without labs, you are guessing. With labs, you have a feedback loop.

The universal baseline panel

Before starting any peptide protocol, the following should be in the green or be explained:

• CBC with differential — baseline red and white cell counts, platelets.
• Comprehensive metabolic panel (CMP) — electrolytes, kidney function (creatinine, eGFR), liver enzymes (ALT, AST, ALP, bilirubin), fasting glucose.
• Lipid panel — total cholesterol, LDL, HDL, triglycerides.
• HbA1c — three-month glucose average.
• TSH and free T4 — baseline thyroid axis.
• Total testosterone and SHBG (for men); estradiol and progesterone for women in a cycle-relevant phase.
• hs-CRP — baseline inflammation.

By peptide class — what to add

Class-specific markers are where most users miss the point of monitoring. Add to the baseline depending on what you are running.

GLP-1 / GIP agonists (semaglutide, tirzepatide, retatrutide)

Run the universal baseline plus a fasting insulin and a lipase before starting. During the cycle, recheck HbA1c, fasting glucose, lipid panel, and lipase at 12 weeks and every 12 weeks after. The lipase matters because pancreatitis is the labeled signal you do not want to miss.

• Baseline: fasting insulin, lipase, calcitonin (in patients with thyroid risk factors).
• On-cycle: HbA1c, fasting glucose, lipid panel, lipase every 12 weeks.
• Watch for: sustained abdominal pain (lipase), heart rate elevation, gallbladder symptoms.

GH secretagogues (CJC-1295, ipamorelin, tesamorelin, MK-677)

The whole class moves IGF-1 and can move glucose. If you are not tracking IGF-1, you are not running this class — you are flying blind through a small therapeutic window.

• Baseline: IGF-1, fasting glucose, HbA1c, fasting insulin.
• On-cycle: IGF-1 at 6–8 weeks; adjust dose to keep IGF-1 in upper-quartile age-adjusted range, not above it.
• Watch for: rising fasting glucose, water retention, peripheral edema, carpal tunnel symptoms.

Melanocortins (MT-II, PT-141)

Cardiovascular and dermatologic monitoring are the priorities. Annual full-body skin check is non-negotiable on MT-II — the molecule darkens existing nevi and changes the baseline of what a 'normal' mole looks like, which complicates melanoma surveillance.

• Baseline: blood pressure log (not single reading), full-body mole map / dermatology baseline.
• On-cycle: annual dermatology review for MT-II.
• Watch for: sustained blood pressure elevation, new or changing nevi, prolonged erection (PT-141).

Healing peptides (BPC-157, TB-500, KPV, GHK-Cu)

Less labwork, more clinical observation. The class has minimal labeled markers because the published human data is limited.

• Baseline: standard universal panel.
• On-cycle: no specific markers; track symptomatic response on the injury or condition being treated.
• Watch for: any unusual mole or lesion change (theoretical angiogenic concern with BPC-157 / TB-500 in cancer history).

How to read your own labs without going insane

Three principles that save people from over-reacting:

• Trends beat single points. A one-time HbA1c of 5.7 means less than a 12-week trend from 5.4 to 5.6 to 5.7.
• Reference ranges are population statistics, not clinical decisions. Being 'in range' is not always 'optimal'; being 'slightly out' is not always 'sick'.
• Symptoms plus labs beats either alone. A normal IGF-1 with carpal tunnel symptoms still warrants a dose decrease.