IL-6
The optimal range for IL-6 (Interleukin-6) is commonly cited as <2 pg/mL, tighter than the standard lab reference range of <7 pg/mL. A primary upstream driver of hs-CRP and systemic inflammation - aging, obesity, and chronic disease all raise it.
How IL-6 ranges relate
The standard lab range vs the optimization-focused target. Illustrative trajectory shows what a 12-week improvement pattern looks like — not real user data.
What IL-6 Measures
IL-6 is a pleiotropic cytokine that drives the acute-phase response (hs-CRP is produced in response to IL-6 signaling in the liver). Chronically elevated IL-6 is one of the hallmarks of "inflammaging" - the low-grade inflammation that accompanies aging and predicts mortality independently of traditional risk factors.
It is produced by adipose tissue (why obesity raises baseline inflammation), activated immune cells, and muscle during exercise. Post-exercise elevations are beneficial; chronic baseline elevations are not.
What Affects This Biomarker
IL-6 is influenced by: adiposity (visceral fat is a major producer), infection, autoimmune activity, exercise (acute rise, lower baseline over time), sleep deprivation, and pharmacologic blockers (tocilizumab in rheum practice). GLP-1s lower baseline IL-6 via weight loss and direct anti-inflammatory effects.
In the Context of Peptide Protocols
Not a standard lab - most users won't see it unless ordering a longevity-focused inflammation panel. When available, trend it alongside hs-CRP. Strong downward movement during a weight-loss or anti-inflammatory protocol is a meaningful biological signal.
Peptides That Commonly Move IL-6
Frequently Asked Questions
What does IL-6 measure?
IL-6 is a pleiotropic cytokine that drives the acute-phase response (hs-CRP is produced in response to IL-6 signaling in the liver). Chronically elevated IL-6 is one of the hallmarks of "inflammaging" - the low-grade inflammation that accompanies aging and predicts mortality independently of traditional risk factors.
What is the optimal range for IL-6?
The optimal range for IL-6 is commonly cited as <2 pg/mL. The standard lab reference range is <7 pg/mL.
What affects IL-6 levels?
IL-6 is influenced by: adiposity (visceral fat is a major producer), infection, autoimmune activity, exercise (acute rise, lower baseline over time), sleep deprivation, and pharmacologic blockers (tocilizumab in rheum practice). GLP-1s lower baseline IL-6 via weight loss and direct anti-inflammatory effects.
Where This Fits in Your Panel
IL-6 is one marker on a fuller panel. The Peptide Blood Work Checklist lays out the complete baseline panel, what to add by protocol type, and when to retest.
See the full blood work checklist →Upload any lab PDF and MyProtocolStack maps your values to IL-6 and 40+ other biomarkers. StackAI interprets the trend in context of your protocol.
Start tracking →Last reviewed: June 2026
Informational only - not medical advice. Reference ranges vary by lab and individual context. Work with a licensed provider to interpret your specific results.