Androgen Receptor Sensitivity (CAG Repeat)MALE
A one-time genetic test measuring the CAG repeat length in your androgen receptor gene. Shorter repeats = a more sensitive receptor; longer repeats = less sensitive.
Explains why two men with identical testosterone can feel completely different — and why some men feel fine at 400 ng/dL while others need 800+ to feel normal. Marek is one of the few places offering this.
The plan of attack
In this order. Most people start at step four, which is why they change five things at once and learn nothing.
- Confirm the number is real
Nothing physiological affects the repeat length. The androgen receptor CAG repeat number is fixed at conception. No hormone, drug, training state or supplement alters it, and a repeat returns the same number. Test once and never repeat it — this is background context, not something to track. - Read it with its partner
A once-in-a-lifetime test that adds real interpretive context to every testosterone result you'll ever get. Draw it alongside: Total Testosterone, Free Testosterone, SHBG (Sex Hormone-Binding Globulin). - Work out which direction is yours
If it's high — Longer repeats — reduced receptor sensitivity. May explain symptoms at 'normal' testosterone levels and support targeting the higher end of range.
If it's low — Shorter repeats — greater sensitivity. Associated with a higher tendency toward androgenic side effects (hair loss, acne, prostate growth) at a given testosterone level. - Fix it in this order
Nutrition. Not modifiable.
Lifestyle. Not modifiable — but it's genuinely useful context for interpreting your symptoms against your numbers.
Supplements. Not modifiable.
Hormones. Helps explain why a 'normal' testosterone level may not be normal for you, and informs the conversation with your provider about where in the range to target.
Compounds. Genuinely useful for anyone on or considering TRT who feels their symptoms don't match their labs.
Work down the list, not across it. Adding a compound on top of an unfixed diet is why generic protocols fail. - Retest
Never — fixed for life. Change one thing at a time, or the retest can't tell you which thing worked.
How to fix it
📚 Zitzmann M, Nieschlag E, J Clin Endocrinol Metab 2003 — AR CAG repeat length and androgen sensitivity.
🩸 Test your Androgen Receptor Sensitivity (CAG Repeat)
Order directly through Marek Diagnostics — no doctor's visit needed, drawn at any Quest location in the US. Code CAMERON applies 10% off automatically.
Order this test — 10% off → Browse all 102 markers →What Androgen Receptor Sensitivity (CAG Repeat) is usually tested alongside
On its own, one marker is a data point. These panels include Androgen Receptor Sensitivity (CAG Repeat) plus the markers that make it interpretable — each names every test, why it is on the list, and loads the whole set into your cart in one click at 10% off.
includes this + 4 more markers — You want the handful of genetic results that actually change what you do — tested once, never repeated.
Would you feel it? Symptoms Androgen Receptor Sensitivity (CAG Repeat) helps explain
People rarely search for a marker — they search for how they feel. These are the complaints where this marker is worth checking, and whether it is a first-line test or a follow-up once the obvious causes are ruled out.
Why your Androgen Receptor Sensitivity (CAG Repeat) might be wrong
Most abnormal results are interference, not disease. These are the things that measurably move this specific marker — check them before you change anything. Each one says whether the number is wrong and should be repeated, badly timed and should be redrawn, or real with a cause worth explaining.
The androgen receptor CAG repeat number is fixed at conception. No hormone, drug, training state or supplement alters it, and a repeat returns the same number.
Test once and never repeat it — this is background context, not something to track.
Shorter CAG repeats associate with greater androgen receptor sensitivity, and the link to clinical outcomes — symptoms at a given testosterone, response to TRT — is real but modest and inconsistently replicated.
Useful context for why two men with the same testosterone feel different. Not a basis for choosing a dose, and no guideline uses it.
Repeat-length counting varies between methods, so 21 at one lab may read 22 at another.
Do not over-read a one or two repeat difference.
What Androgen Receptor Sensitivity (CAG Repeat) means in combination
A single marker tells you a little. Combinations tell you the story — these are the named patterns this marker takes part in, and what each one points at.
The androgen receptor CAG repeat modulates how strongly a given testosterone level is read by the receptor, which is a real part of why identical numbers produce different symptoms. The association with clinical outcomes is modest and inconsistently replicated.
Useful background context. Not a basis for choosing a dose — no clinical guideline uses it, and symptoms plus a properly measured free testosterone remain the decision-makers.
What to test next
Markers rarely answer alone. These are the ones that put Androgen Receptor Sensitivity (CAG Repeat) in context — each with its own full breakdown.
Frequently asked questions
Typically 9–37 repeats; ~20–23 is average in most populations Ranges vary by laboratory and assay — always compare to the range printed on your own report.
Informational. Shorter (<21) means you respond more strongly to a given testosterone level; longer (>23) means you may need a higher level for the same effect.
Longer repeats — reduced receptor sensitivity. May explain symptoms at 'normal' testosterone levels and support targeting the higher end of range.
Shorter repeats — greater sensitivity. Associated with a higher tendency toward androgenic side effects (hair loss, acne, prostate growth) at a given testosterone level.
You can order Androgen Receptor Sensitivity (CAG Repeat) directly through Marek Diagnostics without a doctor's visit — drawn at any Quest Diagnostics location in the US. Code CAMERON applies 10% off automatically.