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ForumsCOA & Analytical TestingInter-lab variability in peptide testing — why results differ between labs Page 3

Inter-lab variability in peptide testing — why results differ between labs

HPLC_Greg Thu, May 21, 2026 at 8:08 AM 15 replies 493 viewsPage 3 of 3
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May 21, 2026 at 12:23 PM#11

Moderator note: Reminder: nothing posted here constitutes medical advice. Consult your healthcare provider.

Tagging this for the weekly digest. 👍

50 17PedsEndoPhilly, SleepDoc_PDX, RegAffairsDC and 47 others
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sarah.morrison
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May 21, 2026 at 12:40 PM#12

Slightly tangential to Inter-lab variability in but InsuranceTom reminded me — does anyone have experience combining this with metformin?

I know it is not exactly on-topic but it seems related enough to ask here rather than starting a new thread. Apologies if this has been covered — I did search first.

9 17roxy_nash, tony_orlando, Dr.NephBHM_UK and 6 others
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Dr.PulmRoch
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May 21, 2026 at 12:57 PM#13
NurseLeah_Nash said:
Follow-up question: how long did you wait before increasing your dose

This is exactly right. NurseLeah_Nash articulated what I have been trying to explain to my doctor for months. The Inter-lab variability in aspect is the most important factor.

12 22AttorneyGrant, DebRD_ATL, KristenIndy and 9 others
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Sigma-Aldrich — Research-Grade Standards

Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.

Shop Reference Standards
fiona_VT
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May 21, 2026 at 1:14 PM#14

Saving this for reference. Top-tier content.

37 5chris_chi24, tampaLisa73, KarenAZ_mom and 34 others
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NicoleRaleigh
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May 21, 2026 at 1:31 PM#15

Adding my data to this Inter-lab variability in discussion:

MetricBaselineMonth 3Month 8
Weight278 lbs243 lbs213 lbs
A1C7.2%5.8%5.4%
hsCRP7.02.01.2

Protocol: Semaglutide 2.4mg/wk, resistance training 3x/wk, protein 1.5g/kg/day.

7 10mike_nyc, VendorMark, COA_Karl and 4 others
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