The Labs To Run Before Your First Peptide

Most people who arrive here curious about peptides do not need one. They need a blood draw.

This is the least exciting page on the site and probably the most useful. The highest-yield step in this entire category costs about $150, takes twenty minutes, and starts with a conversation with your clinician.

Why baseline matters twice

First, because symptoms lie. "Brain fog" is a symptom with maybe fifteen common causes, and only a couple of them are anything a nootropic peptide is even claimed to address. Fatigue, low drive, poor recovery and bad sleep are the same story. The lab tells you which problem you actually have.

Second, because without a baseline you can never tell whether anything you change is working. Start something new with no numbers and you finish it with an anecdote and a feeling. Those are the two least reliable instruments in medicine.

Measure before. Measure again later. Now you have a delta, and a delta is data.

The baseline panel

Ask for these by name. Your physician is the best route, because someone should be reading the results with you; direct-to-consumer labs will also run them.

Metabolic

• Comprehensive metabolic panel (CMP) — liver, kidney, electrolytes, fasting glucose
• Fasting insulin, and HOMA-IR calculated from it
• HbA1c
• Lipid panel with ApoB. ApoB is the number that actually tracks cardiovascular risk; standard LDL-C is a proxy for it.

Hormonal

• Total and free testosterone, drawn in the morning
• SHBG
• Estradiol (sensitive assay)
• Prolactin
• TSH, free T3, free T4
• DHEA-S

Inflammatory and nutritional

• hs-CRP
• Ferritin
• 25-OH vitamin D
• B12 and folate
• CBC with differential

If you are talking to a prescriber about GLP-1-class weight-loss drugs, add a baseline lipase, and be honest about any personal or family history of medullary thyroid carcinoma or MEN2. For that drug class it is a hard stop, not a caution.

What usually explains it

In practice, the pattern is boring and consistent:

• Low ferritin explains a large share of fatigue, particularly in menstruating women, and it is routinely missed because the CBC looks normal.
• An under-active thyroid explains a large share of "fog", weight resistance and cold intolerance.
• Low vitamin D is very common at northern latitudes through the winter.
• Low free testosterone with normal total testosterone — high SHBG — explains a lot of "my labs were fine but I feel terrible."
• Fasting insulin rises years before HbA1c moves. It is the earliest warning you can get.

None of those are fixed by a peptide. All of them are fixable.

Then do the foundation

Once the labs are back and the obvious things are addressed, run S.T.A.R.T.E.D. for ninety days. Sunlight, temperance, air, rest, trust, exercise, diet. It costs nothing, it risks nothing, and it is the only thing on this site we recommend to everyone.

If you still have a specific, stubborn problem after that — a tendon that will not heal, sleep that will not consolidate — bring it to a licensed clinician with your baseline in hand. The Kills explain what the research does and does not show for the compounds people ask about, so you can have that conversation well informed.

That is the whole order of operations. Labs, foundation, then a clinician. Most people run it backwards and then wonder why the expensive part did not work.