Androgen Receptor Sensitivity (Genetic Analysis)

Androgens are male sex hormones—primarily testosterone, DHT, and DHEA-S—that shape muscle mass, strength, libido, and vitality. But these hormones don't operate in a vacuum; their effectiveness depends heavily on the androgen receptor (AR).

Think of the androgen receptor as a lock, and testosterone as the key. Only when testosterone effectively "unlocks" the androgen receptor can it activate the genetic signals responsible for muscle growth, strength gains, sexual health, and overall wellness.

Your androgen receptor sensitivity directly influences how effectively your body responds not only to your natural hormones but also to treatments like testosterone replacement therapy (TRT), fertility protocols, and even hair loss medications like finasteride. Knowing your AR sensitivity helps you fine-tune these treatments, improving outcomes and reducing unnecessary guesswork.

This phenomenon is called interindividual variability, the reason two people with identical testosterone levels, TRT dosages, or even the same hair loss medication (like finasteride) can feel or respond completely differently.

These differences largely come down to your genetics, specifically variations in the androgen receptor (AR) gene that determine how effectively your body responds to testosterone and other androgens.

Think of standard bloodwork as a fuel gauge. It shows how much hormone ("fuel") you have but not how efficiently your body uses that fuel. A half-tank of gas won’t take a sports car nearly as far as a compact sedan. Similarly, individuals with identical hormone levels can experience dramatically different outcomes as a result of differences in their receptor sensitivity.

The AR-CAG is a specific genetic sequence within your androgen receptor (AR) gene, consisting of repeating units known as CAG repeats. The length of this sequence directly influences how sensitive your androgen receptor is to testosterone and other androgens.

Two decades of research demonstrate that your AR-CAG repeat length can profoundly influence diagnosis, treatment decisions, and outcomes related to hormone health. Key insights include:

Improved Diagnosis and Identification of Optimal Testosterone Ranges

• Combining AR-CAG repeat length with traditional blood tests allows for more precise diagnosis of Low-T, helping to establish optimal testosterone ranges tailored specifically to you.

Personalized TRT Dosing

• Men with shorter CAG repeat lengths typically require lower testosterone doses due to greater receptor sensitivity, whereas men with longer repeats often need higher doses to achieve optimal results.

Accounting for Variable Response to Hair Loss Medications (e.g., Finasteride)

• Men with shorter AR-CAG repeats may experience more significant hairline improvement in response to medications like finasteride for hair loss compared to those with longer repeats.

Identifying Symptomatic Patients Above Traditional Low-T Thresholds

• Men with longer AR-CAG repeat lengths are more likely to experience symptoms of low testosterone, even if their blood levels appear "normal," highlighting the need for optimal reference ranges tailored to each individual.

Metabolic impact of TRT

• Variations in AR-CAG repeat length have been associated with differences in insulin sensitivity and body composition in response to TRT

Predicting Changes in Hematological Profile on TRT

• Men with shorter AR-CAG repeats may experience more pronounced changes in hematological markers (such as increased hematocrit and hemoglobin) in response to testosterone therapy, highlighting the value of tailored monitoring and individualized dosing strategies.

Optimizing Fertility Protocols

• AR-CAG repeat length may impact responsiveness to fertility treatment due to the impact of intra-testicular testosterone (ITT) levels on spermatogenesis

On average, it takes 17.2 years for cutting-edge science to become part of standard medical practice—and the gap is likely even longer when you factor in pushback from insurance companies. Marek Health is committed to bridging this gap, democratizing access to advanced diagnostic testing, and continuously translating breakthrough research into meaningful tools that move medicine forward and empower our clients.

AR-CAG repeat length testing itself isn't new. It’s long been available for diagnosing rare diseases like Spinal-Bulbar Muscular Atrophy (Kennedy’s disease), but traditional tests only classify results as "normal" or "abnormal," limiting their ability to measure subtle yet critical variations within the normal range. This test offerred through Marek Diagnostics reports the specific CAG-Repeat length, even within a normal range, to provide the nuance required for it's application in male hormone optimization.

Marek Health is proud to be the first and only provider to bring comprehensive AR-CAG repeat length testing to market, specifically designed for individuals seeking deeper, personalized insights into their hormone profile, androgen sensitivity, and overall health optimization.

Note: While Marek Diagnostics offers self-service labs for independent testing, the Marek Health team includes coaches and board-certified medical practitioners capable of helping you interpret high-leverage biomarkers like AR-CAG repeat length within the context of comprehensive blood testing and personalized health strategies.

• Androgen Receptor Gene Analysis for CAG Repeat Expansion Length

Genetic analysis performed via combination of repeat-primed analysis PCR and fluorescent fragment-length assay.

Important Note: This is an at-home test. Shipping of the testing kit is included.

After placing your order, our team will send you a sample collection kit. Specimen collection kits typically arrive within 1 week of placing your order.

Follow the simple instructions on the kit to provide your sample, and place your kit back in the mail for shipping and testing. Results may take up to 2-3 weeks to arrive.

The AR-CAG repeat test evaluates the genetic sensitivity of your androgen receptors (AR). Shorter AR-CAG repeats are associated with higher androgen receptor sensitivity, meaning stronger testosterone effects at lower hormone levels. Longer repeats correlate with reduced sensitivity, which may contribute to symptoms of androgen deficiency despite normal lab values.