Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

This article is part of the PlexusDx Education Hub — your resource for evidence-based guidance on hormones and fertility. Browse all Hormones & Fertility education

The honest answer is: no — not in the predictive sense the question implies. The PlexusDx Precision Peptide Genetic Test does not forecast whether a specific androgen-pathway protocol will raise your testosterone by a certain amount, produce a particular clinical outcome, or perform better than an alternative approach. That kind of prediction would require knowing your full clinical picture, your baseline bloodwork, your response history, and dozens of variables that no genetic test alone can capture.

But the question matters — because what genetic testing can do is arguably more useful than prediction. It maps the six biological variables that determine how testosterone is produced, bound, converted, and sensed in your body. That map doesn't tell you what will happen. It tells you what terrain your provider is working with — which changes every decision they make, from the first baseline draw to how they interpret every lab result that follows. Across 14 pathways, 49 peptides, and 150+ genetic insights, the Precision Peptide Genetic Test delivers that terrain map with precision.

Prediction vs. Characterization: The Distinction That Matters

These are two different things, and conflating them leads to either overselling or underselling what genetic testing offers in the hormone space.

Prediction means forecasting a specific future outcome: "This protocol will increase your free testosterone by X%, reduce your estrogen to Y level, and produce Z clinical effect." No current genetic test does this — and any product that claims to is making a promise the science doesn't support.

Characterization means mapping the biological architecture that protocols operate within: "Here is how your SHBG genetics set your free testosterone baseline. Here is how your CYP19A1 activity will route testosterone toward estrogen. Here is how sensitively your androgen receptor will read whatever testosterone reaches it." This is what the Precision Peptide Genetic Test delivers — and it is precisely what providers need to make informed decisions about protocol targets, monitoring priorities, and how to interpret the numbers that come back.

Genetics as a guide, not a guarantee. That distinction is not a legal hedge — it's an accurate description of what the science can and cannot do, and why the characterization that genetics provides is genuinely valuable even without predictive certainty.

The Six Variables Genetic Testing Maps — and Why They Matter for Protocol Planning

Here are the six biological variables the Precision Peptide Genetic Test analyzes as 6 Reproductive Health insights — and specifically how each one changes clinical practice when known before a protocol begins:

SHBG — Bioavailability Baseline
High-SHBG genetics mean a larger total testosterone elevation is required to move the free testosterone fraction meaningfully. A provider who knows this upfront sets free testosterone — not total — as the primary monitoring target from day one. Without it, they may chase a total testosterone number while free testosterone remains inadequate. SHBG Genetics: Why Your Free Testosterone Varies covers the bioavailability dimension in full.

CYP19A1 — Aromatization Rate
High-activity CYP19A1 variants will convert a larger fraction of any testosterone elevation into estradiol. A provider who knows this can anticipate the estrogen trajectory rather than reacting to elevated E2 after the fact. It changes whether estrogen monitoring is proactive or reactive — a significant clinical difference. CYP19A1 and Estrogen Conversion in Men covers the aromatization variable in full.

AR (CAG Repeats) — Receptor Sensitivity
Longer AR CAG repeats mean the androgen receptor generates a weaker downstream signal per unit of testosterone. A provider who knows this can contextualize a patient's subjective response against their objective numbers — understanding why a man with "good" testosterone levels may still report suboptimal androgen effects. Androgen Receptor CAG Repeats: Sensitivity Explained covers the receptor dimension in full.

SRD5A2 — DHT Conversion Profile
High-activity SRD5A2 variants produce more DHT from equivalent testosterone substrate. This shapes which androgen-sensitive tissues receive the strongest signal and informs what gets monitored (DHT, prostate health markers) alongside standard testosterone labs. SRD5A2 and 5-Alpha Reductase Genetics covers DHT conversion genetics in full.

LHCGR / FSHR — HPTA Axis and Fertility Dynamics
LH and FSH receptor variants shape how deeply endogenous production suppresses under negative feedback and how readily it recovers when protocols change. For men of reproductive age, FSHR genetics shape the fertility risk profile of the entire protocol conversation. Knowing this before starting is the difference between proactive fertility preservation planning and reactive damage control. HPTA Axis Genetics: LH, FSH, and Fertility Preservation covers the axis dimension in full.

CYP17A1 / CYP11A1 — Upstream Precursor Baseline
Adrenal androgen production — via DHEA and pregnenolone — contributes to the hormonal baseline before testicular production is accounted for. Lower CYP17A1 17,20-lyase efficiency reduces this adrenal contribution, which affects how aggressively any protocol needs to compensate and how DHEA-S levels trend over time. DHEA and Pregnenolone Pathway Genetics covers this upstream source in full.

What Genetic Testing Cannot Tell You — and Why That's Important to Acknowledge

Honesty here builds more trust than overselling. Genetic testing does not:

Predict your current hormone levels. Genetics sets a baseline tendency — your actual testosterone, free testosterone, estradiol, and SHBG at any given moment depend on age, body composition, stress, sleep, nutritional status, medications, and many other variables. Current levels require blood testing.

Predict your clinical response to any specific protocol. Two men with identical genetic profiles can respond differently to the same protocol depending on their baseline health status, how consistently they follow the protocol, how their bodies change over time, and the clinical judgment of their providers. Genetics is one important variable — not the whole picture.

Replace the provider relationship. Interpreting genetic results alongside symptoms, bloodwork, health history, and individual goals is clinical work. The Precision Peptide Genetic Test is designed to inform that conversation — not to substitute for it.

Why the Map Still Matters — Test Before You Invest

None of those limitations change the core value proposition: a provider who knows a patient's SHBG, CYP19A1, AR, SRD5A2, LHCGR, and CYP17A1 genetics is working from a fundamentally more complete picture than one who doesn't. That picture doesn't predict outcomes — but it defines the genetic terrain within which every outcome plays out.

The test before you invest principle isn't about certainty. It's about replacing the largest genetic unknown with a defined, evidence-based starting point before protocols begin rather than discovering your genetic architecture through months of trial, adjustment, and error. The complete framework for why these six variables make this case is in the Why TRT Works for Some Men and Not Others: The Genetic Answer synthesis post and the Complete Guide to Genetic Men's Hormone Testing.

The Precision Peptide Genetic Test analyzes how your genes influence hormone-related biological pathways. It does not recommend, prescribe, or determine which peptides you should use. Consult a qualified healthcare provider before beginning any peptide protocol.

Ready to map the biological variables behind your hormone picture? Take the Precision Peptide Genetic Test

Frequently Asked Questions About Genetic Testing and TRT Response

Can genetic testing predict whether TRT will work for me?

No — genetic testing cannot predict outcomes on any specific protocol. What the Precision Peptide Genetic Test delivers is a map of six biological variables — SHBG, CYP19A1, AR, SRD5A2, LHCGR, and CYP17A1 — that shape how testosterone behaves in your body. That baseline informs protocol planning but does not predict results.

What is the difference between predicting TRT response and mapping TRT genetics?

Prediction means forecasting a future outcome. Genetics mapping means identifying the biological variables that shape how testosterone is produced, bound, converted, and sensed — without forecasting outcomes. The Precision Peptide Genetic Test does the latter: 6 Reproductive Health insights that define your biological terrain, not a prediction of how any specific protocol will perform.

Does knowing my genetics change how a provider approaches TRT?

Yes. A provider who knows a patient's SHBG genetics sets free testosterone as the primary target. CYP19A1 activity informs estrogen management strategy. AR CAG repeat length frames receptor sensitivity. Six genetic variables known before protocols begin change what gets monitored and how results are read. The Precision Peptide Genetic Test delivers all six.

This article is part of the PlexusDx Education Hub. Browse all Hormones & Fertility education

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.