TRT Lab Interpretation Guide
How to read and understand your TRT blood work — every marker explained with optimal ranges.
Essential TRT labs and when to draw them
Baseline (before starting): Total T, Free T, SHBG, E2 (sensitive), LH, FSH, Prolactin, CBC, CMP, PSA (if over 40), Lipid panel, TSH, Vitamin D. On TRT monitoring (every 6-12 months minimum): Total T, Free T, SHBG, E2 (sensitive), CBC (hematocrit), PSA (if over 40), CMP. Timing matters: for once-weekly injections, draw at trough (right before next injection). For twice-weekly, draw on injection day before your shot. This gives you the lowest point measurement, which is the standard for dose adjustment.
Testosterone levels: total, free, and bioavailable
Total T is the headline number but doesn't tell the full story — most testosterone is bound to SHBG and albumin. Free T (unbound, ~2-3% of total) is what's actually available to tissues. Bioavailable T (free + albumin-bound) is a middle ground. On TRT, aim for total T in the mid-to-upper normal range (500-900 ng/dL) at trough, with free T comfortably in range. Your sweet spot may be different — some men feel best at 600, others at 900. Above 1,000-1,100 ng/dL, side effect risk increases without proven additional benefit.
SHBG and its impact
Sex Hormone Binding Globulin (SHBG) is the 'traffic controller' of your sex hormones. High SHBG: binds up too much testosterone, leaving you with low free T even when total T looks good. More frequent injections often help. Low SHBG: testosterone clears too fast, causing peaks and troughs. Less frequent injections or larger doses may work better. Normal SHBG: once-weekly injections usually work well. Understanding your SHBG is key to choosing the right injection frequency.
Estradiol (E2) management
Estradiol (E2) is not the enemy — it's cardioprotective, neuroprotective, and essential for libido and bone health. On TRT, some T converts to E2 via aromatase. The goal is balanced E2, not crushed E2. Get the 'sensitive' or 'ultrasensitive' estradiol test — the standard test overestimates E2 in men. Ideal E2: roughly 20-40 pg/mL, or about 5% of your total T level. Low E2 symptoms: joint pain, low libido, dry skin, fatigue — often mistaken for high E2. High E2 symptoms: bloating, emotional sensitivity, nipple sensitivity (not necessarily gyno). Don't treat a number — treat symptoms, and only after verifying with the sensitive test.
Hematocrit, PSA, and other markers
Hematocrit (HCT): TRT stimulates red blood cell production. Above 52-54%, risk of blood clots increases. Management: donate blood, lower dose, increase injection frequency, or therapeutic phlebotomy. PSA: TRT can slightly increase PSA in some men. Any significant rise needs urological evaluation. Rule of thumb: PSA should not increase more than 0.5-1.0 ng/mL per year on TRT. Liver function: monitor ALT/AST, especially with oral testosterone. Lipids: TRT typically either neutral or slightly improves HDL/LDL. TSH/Thyroid: low thyroid can mimic low T symptoms — always check. Prolactin: elevated prolactin suppresses T — if high, needs pituitary investigation.
Frequently asked questions
When should I get blood work on TRT? +
Standard schedule: baseline before starting, 6-8 weeks after starting or changing dose, then every 6 months. Once stable, annual labs may suffice. Always draw at trough (right before your next injection) for dose assessment. More frequent testing is warranted if you're troubleshooting side effects or adjusting protocols.
What's the difference between standard and sensitive estradiol? +
The standard E2 test uses immunoassay and can overestimate E2 by 20-40% in men, sometimes showing falsely high results. The sensitive (LC-MS/MS) test is far more accurate for male E2 levels. Always request the sensitive/ultrasensitive assay — it prevents unnecessary AI use based on inflated readings.
My hematocrit is 52% — should I worry? +
52% is at the upper limit but not dangerous on its own. Donate blood and re-check in 2-3 months. If it stays elevated, reduce your dose or increase injection frequency. Staying hydrated before labs also helps. Therapeutic phlebotomy is an option if donation isn't possible. Above 54%, take action promptly.
What's a good free T level on TRT? +
Most men feel best with free T in the mid-to-upper normal range (15-25 ng/dL or 150-250 pg/mL, depending on the lab). The ratio matters more than the absolute — free T should be roughly 2-3% of total T. If SHBG is high, you may need higher total T to get adequate free T.