T Nation

Testing Peak vs Trough

So going for first blood test since switching to injections. Curious why it’s always taught to test at trough. Shouldn’t we know how high the drug we are taking is getting us to? Would seem to me equally important .

If you only test peak and let’s say it’s 550, your trough could be in low T land days later and you would never know unless your start testing trough.

Testing trough is more useful if it still sufficiently elevated because that would mean your peak is even higher and that’s not a concern, being in the low ranges is a concern.

If you were to test peak how many hours post injection would you do

I agree they are equally important. Most clinics want the trough.

Knowing your peak will help you keep your Free T within range. Why is that important?
If you run your Free T over range for too long you can start seeing negative effects like thicker blood HCT.
E2 too high requiring the use of an AI. Prolactin over range. Over range E2 with over range prolactin for an extended period of time is how Gyno forms.

What are you injecting?
T e & cyp 48hours
Testosterone Propionate is the shortest-estered testosterone I’d draw at 24hours post injection.

Several things here:

When managing TRT and adjusting dosing, you want to always obtain blood at the same point relative to injection(s). The day of the injection, prior to the injection, is easiest. This is obviously more important as the time between injections increases. For anyone taking daily injections, or using creams or gels, it does not matter.

Some doctors use trough because they want you at the lowest level, for the record. This likely is more of a factor when insurance coverage is involved. Also, on the chance that a state medical board would look into prescribing practices, they do not want the appearance of overdosing their testosterone patients.

One can extrapolate backwards from trough and project levels throughout the week, however individual metabolism varies and this is not an exact approach.

This will vary from patient to patient. Around 24 hours.