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Evidence-based GLP-1 & peptide discussion since 2023
ForumsLab Results & BiomarkersWhat labs should I ask for? Doctor only did basic panel — anyone have experience?

What labs should I ask for? Doctor only did basic panel — anyone have experience?

dan_philly Sat, Oct 19, 2024 at 9:20 AM 20 replies 1,973 viewsPage 1 of 4
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dan_philly
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Jul 2024
Philadelphia, PA
Oct 19, 2024 at 9:20 AM#1
I'm fortunate enough to have both a PCP and an endocrinologist managing me while on semaglutide (prescribed, Wegovy 1.7mg). The problem is they order completely different lab panels and sometimes give conflicting interpretations. Here's what each one orders: PCP orders (annually): - CMP - CBC - Lipid panel - A1C Endo orders (every 3-4 months): - A1C - Fasting insulin + glucose (calculates HOMA-IR) - Lipid panel with particle size (NMR LipoProfile) - TSH, Free T4 - Lipase - hs-CRP - C-peptide My PCP says my lipid panel is "fine" (LDL 118, HDL 48, TG 145). My endo looked at the NMR LipoProfile and said my LDL particle number is still elevated at 1380 nmol/L (goal <1000) and my small dense LDL is 42% which is "concerning" even though the standard LDL looks borderline acceptable. Who's right? And which labs should I actually be getting?
50 20DadBodDave, AmyNC_wife, SkepticalSean and 47 others
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anders_CPH
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Feb 2024
Copenhagen, DK
Oct 19, 2024 at 9:45 AM#2
Your endo is doing a more thorough job, full stop. Here's why: Standard lipid panel gives you LDL-C (cholesterol concentration). This is like counting the number of passengers on buses without counting the buses. You could have 10 buses with 5 passengers each or 50 buses with 1 passenger each — same total passengers, very different risk. NMR LipoProfile counts the actual LDL particles (LDL-P). An LDL-P of 1380 means you have MORE particles than ideal even though each one isn't carrying that much cholesterol. More particles = more chances for particles to penetrate arterial walls = more atherosclerotic risk. Your endo is also checking: - Fasting insulin + HOMA-IR: Measures insulin resistance directly, not just glucose control. You can have "normal" glucose with sky-high insulin (compensated IR). This is way more nuanced than A1C alone. - C-peptide: Measures how much insulin YOUR pancreas makes. Important for understanding your metabolic health trajectory. - Lipase: Monitors pancreatic safety on GLP-1 - hs-CRP: Inflammation marker with cardiovascular significance - Thyroid: Screening for GLP-1 thyroid concerns (low risk but worth monitoring) Your PCP's panel is a basic annual screening. Your endo's panel is metabolic optimization monitoring. Both are valid for their purposes but if you can only pick one approach, go with the endo's.
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chris_chi24
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Sep 2024
Chicago, IL
Oct 19, 2024 at 10:10 AM#3
I'll push back slightly. Your PCP isn't "wrong" — they're doing standard of care screening which is appropriate for the general population. NMR LipoProfile, fasting insulin, and C-peptide are not standard guidelines-based tests for most patients. They're advanced testing that many insurance plans won't cover. That said, for someone on GLP-1 therapy actively managing metabolic disease, your endo's approach IS better. It's just not what PCPs are trained to do or what guidelines tell them to order for routine care. The solution isn't "who's right" — it's coordination. Ask your endo to send a note to your PCP explaining what they're monitoring and why. Ask your PCP to defer metabolic lab ordering to the endo. This prevents duplicate testing and conflicting interpretations.
Last edited: Oct 19, 2024 at 1:10 PM
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FranDenver
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Oct 2024
Denver, CO
Oct 19, 2024 at 10:35 AM#4
That's a great point about coordination. They're in different health systems so they don't share records, which is part of the problem. I've been manually carrying results between them. Another example of conflicting interpretation: my A1C is 5.4%. PCP says "perfect, no diabetes concerns." Endo says "your A1C is good but your fasting insulin is 18 mIU/L which is still elevated (ideal <8) and your HOMA-IR is 4.1 (ideal <1.0, insulin resistant >2.5). You still have significant insulin resistance that the A1C is masking because the semaglutide is compensating." That's a completely different clinical picture depending on who you listen to.
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Dr.PeteFamMed
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Oct 19, 2024 at 12:52 PM#5
Your endo is 100% right on this one and it illustrates exactly why fasting insulin matters. A1C of 5.4% + Fasting insulin of 18 + HOMA-IR of 4.1 = compensated insulin resistance Your body is producing 2-3x the normal amount of insulin to keep your blood sugar at 5.4%. The semaglutide is helping by enhancing insulin sensitivity and secretion patterns, but the underlying insulin resistance hasn't fully resolved yet. This is actually useful information because it tells you: 1. If you stop sema, your glucose will likely spike because you're still IR 2. You have more metabolic healing to do (continued weight loss, exercise, dietary improvement) 3. Your cardiovascular risk is higher than A1C alone suggests Here's a simplified HOMA-IR interpretation: | HOMA-IR | Interpretation | |---------|---------------| | < 1.0 | Optimal insulin sensitivity | | 1.0 - 1.9 | Normal range | | 2.0 - 2.5 | Early insulin resistance | | 2.5 - 5.0 | Significant insulin resistance | | > 5.0 | Severe insulin resistance | At 4.1, you're solidly insulin resistant despite "normal" glucose and A1C. This is the hidden iceberg that standard labs miss.
Last edited: Oct 19, 2024 at 1:52 PM
46 16FranDenver, Dr.BariatricHTX, LindaRN_retired and 43 others
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