How Testosterone Therapy Is Monitored

Testosterone therapy is not a prescription you fill and forget. The hormone changes the blood, the prostate and the body's own signaling, and each of those needs to be looked at on a schedule. A man handed a vial and told to come back in a year is not being treated well.

Before the first dose

We confirm the diagnosis with two morning blood draws, because testosterone peaks early in the day and a single low afternoon value proves nothing. The baseline panel is total and free testosterone, SHBG, estradiol and LH. LH is the pituitary's signal to the testes. If testosterone is low and LH is high, the testes are the problem. If both are low, the signal is the problem, and that changes the plan. We also get a hematocrit and, for men over 40, a PSA.

What we check on treatment

• Testosterone. Rechecked about three months in, then at least yearly. For injections we draw midway between doses. For a gel we draw a few hours after it goes on. The aim is a level in the middle of the normal range, not the top of it.
• Estradiol. Some testosterone converts to estradiol, and a man needs it for bone, mood and libido. Too high and he may get breast tenderness or water retention. Too low, usually from an aromatase blocker given too freely, and bone pays the price over years. We adjust the testosterone dose before reaching for another drug.
• Hematocrit. Testosterone tells the marrow to make more red cells, and thicker blood raises the risk of a clot. We check it at three months, at a year, then yearly. Injections push it up more than gels do. A value above 54 percent means the dose comes down or the form changes.
• PSA. In trials testosterone has not been shown to cause prostate cancer, but it can feed one that is already there. We recheck PSA at three to twelve months and then on the usual screening schedule. A rise of more than 1.4 points in a year, or a level above 4, goes to a urologist before anything else changes.

Why the intervals matter

The three month check exists because that is when the dose declares itself: levels have reached a steady state, hematocrit has had time to climb, and symptoms have had time to change. Adjusting earlier is guessing. Waiting a year to find a hematocrit of 56 is a risk nobody needs to take.

The yearly check catches slow drift. Weight changes, sleep apnea develops, a man ages into a different dose. We also ask about sleep, blood pressure and mood, and for younger men whether fertility matters, since testosterone suppresses sperm production.

That's why we check it, on a schedule. If you are on testosterone and the last blood draw was more than a year ago, it's worth a conversation.

This article is educational and is not medical advice.

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