For TRT it’s pretty simple and straightforward.
Test these labs before starting TRT to establish your baseline, and continue monitoring them after beginning treatment. During the first year, you’ll check them fairly often (typically every 3 or 4 months) to see how your body responds. Once your levels are stable and predictable, testing can usually be reduced to every 6 months, and eventually once a year after several years of consistent, steady results.
CBC (Complete Blood Count) is the single most important lab on TRT. Testosterone stimulates red blood cell production, which can raise hematocrit and hemoglobin. If hematocrit climbs too high, blood becomes more viscous (“thicker”), increasing the risk of clotting, stroke, and cardiovascular strain.
Estradiol (since you are male, you will need the “ultra sensitive” or “sensitive” estradiol test). Excess estradiol can lead to symptoms like gynecomastia (breast tissue growth), water retention, mood changes, and libido issues, while levels that are too low can cause joint pain, low libido, and poor cardiovascular support.
(I recommend not trying to drive estradiol excessively low. Estradiol is essential for health. Medications to lower E2 are generally only needed if you experience symptoms of high estrogen. On a properly dosed TRT regimen, estradiol should remain in a healthy range; if it’s elevated, the safer approach is usually to adjust your testosterone dose downward rather than aggressively suppress estrogen)
Lipids (cholesterol) is important because TRT can negatively affect cholesterol balance, particularly by lowering HDL (“good” cholesterol) and, in some cases, raising LDL.
CMP (Comprehensive Metabolic Panel) matters on TRT because it shows how well your body is tolerating the therapy overall. It checks liver enzymes to catch liver stress, kidney markers to monitor filtration and hydration status, electrolytes that affect blood pressure and heart rhythm, and glucose to flag changes in blood sugar control. It’s a broad safety panel that helps put the rest of your labs in context.
PSA (Prostate-Specific Antigen) is important on TRT because testosterone can stimulate prostate tissue. Monitoring PSA helps detect prostate enlargement or early signs of prostate cancer, especially in older men or those with risk factors. Regular PSA checks give a baseline and allow trends to be tracked safely over time.
Total Testosterone measures the overall amount of testosterone in your blood, including both the fraction bound to proteins and the fraction that’s free.
Free Testosterone measures only the unbound portion that is biologically active and able to enter cells to exert effects.
Free Testosterone and Total Testosterone simply help identify how you’re responding to a particular dosage. Everyone responds a little differently. 100mg a week might put me at 1000 (ng/dL) but you might only reach 600 (ng/dL).
You’ll hear about other blood markers, but for standard TRT, the ones mentioned here are the most important. Other labs typically only become critical if you start using higher testosterone doses or additional compounds, where more specialized monitoring is required for safety.
