How to Read Your TRT Bloodwork: A Patient's Guide

Getting bloodwork on TRT isn't just a formality — it's the steering wheel for your entire protocol. Your numbers tell you whether your dose is right, whether your body is converting too much testosterone to estrogen, whether your red blood cells are getting too thick, and whether your prostate is responding appropriately.

The problem is that most lab reports give you a number and a reference range — but don't tell you what's actually optimal, or what the number means in the context of TRT specifically. Let's fix that.

Why Understanding Your Labs Matters

Many men hand their lab report to their provider and accept whatever they're told. That's fine if your provider specializes in TRT. But if you're working with a general practitioner who sees two TRT patients a year, understanding your own numbers gives you the ability to have an informed conversation and advocate for appropriate adjustments.

It also helps you catch things early. A slowly rising hematocrit, a creeping PSA, or an estradiol that's drifting high — these are things you can spot before your next appointment if you know what to look for.

Total Testosterone

What it measures: The total amount of testosterone in your blood — both the portion bound to proteins (SHBG and albumin) and the small unbound fraction.

Standard lab reference range: Roughly 264-916 ng/dL (varies by lab)

What to aim for on TRT: Most TRT-specialized clinics target the upper portion of the reference range: 600-900 ng/dL at trough (your lowest point, typically the morning before your next injection). Traditional endocrinologists may be comfortable with 450-600 ng/dL.

Important context: Total testosterone alone doesn't tell the full story. A man with total T of 700 ng/dL but very high SHBG might have less bioavailable testosterone than a man with total T of 500 ng/dL and low SHBG. That's why free testosterone matters.

Free Testosterone

What it measures: The 1-2% of testosterone that's not bound to any carrier protein. This is the fraction that's directly available to enter cells and activate androgen receptors — the testosterone that actually "does things."

Standard reference range: Roughly 5-21 ng/dL (varies significantly by lab and assay method)

What to aim for on TRT: Upper quartile of the reference range. The exact number depends on the lab's assay, but generally you want free T in the upper 25% of whatever range your lab uses.

Why it matters: Some men have "normal" total testosterone but low free T because their SHBG is soaking up most of it. These men often feel symptomatic despite a total T number that looks fine on paper. Free T tells you what's actually bioavailable.

Estradiol (E2)

What it measures: The primary form of estrogen in men. A portion of your testosterone is converted to estradiol by the aromatase enzyme, especially in fat tissue.

Standard reference range: 10-40 pg/mL (for men; use the "sensitive" or LC-MS/MS assay — standard immunoassays are unreliable in men)

What to aim for on TRT: Generally 20-35 pg/mL. High enough to protect bones, heart, and brain function. Not so high that you get water retention, mood swings, or gynecomastia.

When to be concerned:

• Too high (>40-50 pg/mL): May cause water retention, bloating, mood instability, nipple sensitivity, decreased libido. Your provider may adjust your dose, increase injection frequency, or consider a low-dose aromatase inhibitor
• Too low (<15 pg/mL): Can cause joint pain, fatigue, depression, low libido, and long-term bone density loss. Estrogen is vital for men — crashing it is counterproductive

Critical note: Always request the "sensitive" estradiol assay (LC-MS/MS), not the standard immunoassay. The standard test was designed for women and is inaccurate at the lower ranges found in men. Most TRT clinics know this; many general labs default to the wrong test.

Hematocrit and Hemoglobin

What it measures: Hematocrit is the percentage of your blood volume occupied by red blood cells. Hemoglobin measures the oxygen-carrying protein inside those red blood cells.

Standard reference range: Hematocrit 38.3-48.6% (varies by lab); Hemoglobin 13.2-16.6 g/dL

The TRT concern: Testosterone stimulates erythropoiesis (red blood cell production) in the bone marrow. This is the most common side effect of TRT — elevated hematocrit occurs in 11-20% of men on injectable testosterone.

When to act: Most clinical guidelines flag hematocrit above 52-54% as the threshold for intervention. At this level, blood viscosity increases significantly, raising the risk of blood clots, stroke, and other thromboembolic events.

What your provider will do: Options include reducing your testosterone dose, increasing injection frequency (which can lower peaks), switching delivery methods, or therapeutic phlebotomy (blood donation or medical blood removal).

SHBG (Sex Hormone-Binding Globulin)

What it measures: A protein produced by the liver that binds to testosterone and holds onto it tightly, making it biologically unavailable.

Standard reference range: 10-57 nmol/L

Why it matters: SHBG is the bridge between your total testosterone and your free testosterone. High SHBG means more of your testosterone is "locked up" and unavailable. Low SHBG means more is free — but it also clears faster.

What affects SHBG:

• Raises SHBG: Aging, thyroid hormones, liver disease, low body fat, certain medications
• Lowers SHBG: Obesity, insulin resistance, high-dose androgens, hypothyroidism

Clinical relevance on TRT: Men with very high SHBG may need higher testosterone doses to achieve adequate free T levels. Men with very low SHBG may aromatize more and need more frequent (smaller) injections to avoid sharp peaks.

PSA (Prostate-Specific Antigen)

What it measures: A protein produced by the prostate gland. Elevated levels can indicate prostate enlargement, inflammation, or cancer — though PSA is not a cancer-specific test.

Standard reference range: Generally <4.0 ng/mL (age-dependent)

On TRT: PSA typically rises slightly when you start testosterone — usually 0.3-0.5 ng/mL above baseline — then stabilizes. This is a normal response, not a sign of cancer. The TRAVERSE trial confirmed that TRT does not increase prostate cancer risk.

When to investigate further: A rapid PSA velocity (increase of >0.75 ng/mL per year), a PSA that continues climbing well beyond the initial 3-6 month adjustment period, or an absolute PSA above 4.0 ng/mL warrants a conversation with your provider and potentially a urology referral.

Other Important Markers

LH and FSH: These pituitary hormones will be suppressed to near zero on TRT. This is expected — exogenous testosterone tells your brain to stop signaling for natural production. If you're on TRT and your LH is still elevated, it may indicate the dose isn't high enough or there's an absorption issue.

Lipid panel: TRT can modestly affect cholesterol, typically lowering HDL slightly. Monitor annually.

Liver function (AST/ALT): Relevant primarily for oral testosterone (like Kyzatrex). Injectable TRT bypasses the liver, so liver enzymes typically aren't affected. Still worth monitoring at baseline.

Thyroid (TSH, Free T4): Not directly affected by TRT, but thyroid dysfunction can mimic or compound low T symptoms. A baseline thyroid panel is good practice.

Metabolic panel (glucose, A1C, insulin): TRT can improve insulin sensitivity and metabolic markers over time. Tracking these shows the broader health benefits of optimization.

When to Draw Labs (Timing Matters)

When you get your blood drawn relative to your injection matters enormously:

For diagnostic purposes (before starting TRT): Draw blood in the early morning (7-10 AM) when testosterone naturally peaks. Two separate morning draws below 300 ng/dL are required for a clinical diagnosis of hypogonadism per AUA guidelines.

For monitoring on TRT: Draw blood at your trough — the lowest point in your dosing cycle. For men injecting twice per week, this is the morning before your next injection. Trough levels represent your "floor" — the minimum testosterone your body is working with.

If your trough total T is 600-900 ng/dL and you feel good, your protocol is likely well-dialed. If your trough is 400 ng/dL and you're still symptomatic, there may be room for dose adjustment.