Key biomarkers explained in plain language, what they measure, what optimal looks like, and why they matter before any peptide research. Test first. Always.
Without baseline labs you have no way to know what's changing, what's working, or what needs attention. Numbers give your research context it can't have without them.
Certain biomarker patterns make specific peptide research inappropriate or higher risk. Labs reveal what symptoms can't, and often point to a different root cause entirely.
Repeat labs at 8–12 week intervals give you objective data instead of guesswork. Without before-and-after measurements, you have no way to evaluate what your research is doing.
Insulin-like Growth Factor-1
Insulin-like growth factor 1, a growth-axis marker involved in growth-hormone signaling, reviewed alongside metabolic and hormone markers. Educational context only.
Related goals
Learn More →Testosterone Biomarkers (Overview)
Overview of the testosterone-related markers — total testosterone, free testosterone, SHBG, LH, FSH, and DHEA-S — and how they are reviewed together. Educational context only.
Related biomarkers
Learn More →Total Testosterone (bound + unbound)
A commonly measured hormone marker: the combined amount of testosterone circulating in the blood, reviewed alongside free testosterone and SHBG. Educational context only.
Related biomarkers
Learn More →Free Testosterone (unbound fraction)
The unbound fraction of testosterone not attached to SHBG or albumin, commonly reviewed alongside total testosterone and SHBG. Method-dependent. Educational context only.
Related biomarkers
Learn More →AM Serum Cortisol
A steroid hormone produced by the adrenal glands that follows a daily rhythm, commonly reviewed in adrenal-related and hormone-related lab panels. Educational context only.
Related goals
Learn More →High-Sensitivity C-Reactive Protein
High-sensitivity C-reactive protein, an inflammation-related marker made by the liver, reviewed alongside metabolic and lipid markers. Educational context only.
Related goals
Learn More →Iron Storage Protein
"The body's iron-storage protein and the standard marker of iron reserves, but it also rises with inflammation."
Related goals
Learn More →Fasting Serum Insulin
Insulin measured after a fasting period, a glucose-related marker that provides insulin-response context alongside fasting glucose and HbA1c. Educational context only.
Related goals
Learn More →Fasting Blood Glucose
A point-in-time glucose-related marker measured after a fasting period, commonly reviewed alongside HbA1c and fasting insulin. Educational context only.
Related goals
Learn More →Glycated Hemoglobin
Glycated hemoglobin, a longer-term glucose-related marker that reflects average glucose exposure over the life of red blood cells. Educational context only.
Related goals
Learn More →ALT, AST, GGT
"A standard blood panel that offers a window into liver health, often reviewed as a baseline in metabolic research."
Related goals
Learn More →25-OH Vitamin D
"Often called the sunshine vitamin, but it works more like a hormone, affecting immune function, mood, testosterone, and bone health all at once."
Related goals
Learn More →Thyroid Stimulating Hormone
"The signal your brain sends to your thyroid, high TSH means the thyroid isn't responding enough, low TSH means it may be overactive."
Related goals
Learn More →Sex Hormone Binding Globulin
Sex hormone-binding globulin, the hormone-binding protein made mainly by the liver that binds testosterone and estradiol and adds context alongside total and free testosterone. Educational context only.
Related goals
Learn More →Luteinizing Hormone & Follicle Stimulating Hormone
Pituitary hormones that provide pituitary-gonadal signaling context, commonly reviewed alongside testosterone, SHBG, and free testosterone. Educational context only.
Related goals
Learn More →Estradiol (E2)
Estradiol (E2), a major form of estrogen present in all sexes, commonly reviewed alongside testosterone, SHBG, and other sex hormone markers. Educational context only.
Related goals
Learn More →Apolipoprotein B
Apolipoprotein B, a lipid-related marker that provides a particle-number-related view of atherogenic lipoproteins, reviewed alongside lipid and metabolic markers. Educational context only.
Related goals
Learn More →Dehydroepiandrosterone Sulfate
Dehydroepiandrosterone sulfate, an adrenal androgen-related marker commonly reviewed alongside testosterone, SHBG, and other hormone markers. Educational context only.
Related goals
Learn More →Plasma Homocysteine
"An amino acid byproduct that builds up when methylation pathways aren't working well, elevated levels are linked to cardiovascular and cognitive risk."
Related goals
Learn More →Three tiers of testing, ordered by what's needed before each stage of research. Work through them in sequence with a licensed healthcare provider.
hsCRP · Fasting Glucose · Fasting Insulin · HbA1c · TSH · Vitamin D · Comprehensive Metabolic Panel · CBC with diff
"This panel gives you the metabolic, inflammatory, and thyroid context needed for any peptide category."
IGF-1 · Total & Free Testosterone · SHBG · LH & FSH · Estradiol · AM Cortisol · Free T3 · Free T4 · Anti-TPO
"Required before Ipamorelin, CJC-1295, Sermorelin, or any GH secretagogue research."
ApoB · DHEA-S · Homocysteine · Ferritin · Omega-3 Index · Uric Acid · NAD+ levels
"For those working with a longevity or functional medicine clinician on a multi-peptide protocol."
The Lab Testing Guide explains exactly how to prepare, what to order, and how to read your results in the context of peptide research.