T Nation

T Levels with Weekly Injections


I have been on TRT for a year with a 50mg Test Cyp/wk. The results have been pretty good. I have seen where 2x a week is advisable.

My question is how fast do T levels rise and fall throughout the week on once per week injections? I have had my levels tested twice while on TRT. Both times were in the 600s, but I had one test the day after, and another one done 5 days after.

Someone told me that your levels can swing 200 or so with weekly injections, is this true? I think my once per week is fine, but I'm wondering if if can be better. BTW my wife says I get moody sometimes...


Once a week is fine for some people, not for others…it depends on how quickly your body strips away the ester and absorbs the T…

The fact that you only need 50 mg/week and that your levels are pretty constant one day and 5 days after an injection tells us that your body is extraordinarily slow at peeling back the ester and delivering the T…which is perfectly fine

The normal half life of cypionate and ethanate esters (which re the most common used for TRT in the US) is about 1 week…which means that if you inject 100 mg on Day 1, about 50 mg will be remaining on Day 7…25 mg on Day 14…etc…But if you are injecting once a week, you are adding to that, so if you inject on day 7 (100 mg) you are increasing your levels to 100 mg (new) + 50 mg (remaining) = 150 mg…if you keep injecting 100 mg every 7 days, your steady state serum levels will approach 200 mg/max…I hope that makes sense

Re: your moodiness…could be a ton of things…if you want to discuss and see if there’s anything hormonally there to be concerned about, start a thread and post your labs…most common culprits are cortisol and E2 (and low T).


Read the advice for new guys sticky, then the protocol for injections sticky. Please do not post into the stickies.

If you change lab timing, then the changed results are more of a result of the timing and not useful. Test 12 way between injections and do not change that. Don’t do labs at at/when you see your doc unless timing is right.

Moody is probably elevated E2.


Read the section on pharmacokinetics: