T Nation

When to Take Blood Sample?

Hi everyone

I’ve switched up my protocol to once every 5 days

how many hours after injection is it best for me to take the blood sample?

I want to know if I’m high normal.

You are supposed to wait 6 weeks to do labs after dosing changes and draw labs at trough. If you really want to know peak levels, test 48 hours after your injection.

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The day of injection, BEFORE the injection. Trough numbers are what you want.

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But how will trough numbers tell me if I’m high normal?

Thank you

Why doesn’t everyone measure at peak?

No. Almost no one does. You want to know what your levels are at their lowest as that’s what most here base their protocol on.

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Your peak levels are short lived and hormones start dropping rapidly, your trough and how you feel is a better measure of protocol success.

Imagine for a moment you measure at peak, you could be lower at trough and never know it and symptomatic wondering what is going on.

Also if your doc measures at trough, it keeps him out of trouble and you are allowed a higher dosage versus measuring at peak and reducing your dosage because levels are out of range if only temporarily.

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Generally, a PCP/GP will not remeasure. Urologists and endocrinologists are more likely to, but many of them do not since they will follow the accepted protocols (for them) of 200mg every two to four weeks, and that’s it regardless of levels as far as they are concerned.

Even some TRT practices will not recheck. Most do and it is usually recommended to get levels checked at their lowest, which as mentioned, will be on the day of the injection, prior to it. The point of that is if you are not responding acceptably, your levels at your lowest will be the most helpful when it comes to making dosing adjustments.

Among TRT practices, it is well known that your levels will be significantly higher earlier in the injection cycle. It’s expected, even ideal, and not of a concern as long as the dose is reasonable and the trough level is as well. Very few need over 200mg a week.

If you’re simply curious to see where you are at peak, levels at 24-48 hours post injection will tell you.

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A graph will probably make more sense and will also demonstrate why you should wait at least 6 weeks before you have labs drawn. A couple of things you need to understand:

  • It takes a couple of hours before the T-cyp you inject to begin releasing molecular T into your system. It typically peaks at about 24-36 hours after you inject. This is what guys refer to as the "peak’ value.

  • The T is slowly released into your system over time. The half life of T-cyp is about 4.5 days and the functional residence time is about 8.5 days. This means that half of it is gone (metabolized and excreted) in 4.5 days and nearly all of it in about 8.5 days.

  • Guys inject at various frequencies. I personally inject on an every 3 day schedule (E3D). I always run labs just prior to the next scheduled injection. This is the lowest level of T during the 3 day injection cycle which is called the nadir (some refer to it as the trough). This nadir is typically recommended because you want to establish a protocol where you feel good the entire injection cycle, so you don’t want your nadir level to go below the point where symptoms are abated.

Here are two graphs comparing the amount of T released per day at two different injection protocols. The first is 44mg E3D (102mg/week) and the second is 100mg E7D (100mg weekly). Both are approximately the same overall weekly dose but result in substantially different peak and nadir values. Keep in mind that the average adult male produces about 7mg of T per day.

100 mg T-Cyp Every 1 Week

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thanks for all the helpful information guys

Hey guys

when I woke up i went to take 1g of finastride but I accidentally took 1g of Arimidex instead lool

I wonder what will happen…

Also do I have to wait another 6 weeks from today before my blood test?


Never heard of it. Is it the generic form of Finasteride?

Finasteride. I misspelled it

Anastrozole has a half life of 50 hours. That means every 50 hours about half of what was previously there is gone. A rule of thumb i use is that a drug needs to go through about 6 half lives (300 hours/12.5 days in this case) to be essentially all gone. However, the functional life is usually much shorter. That is, after a few days, it’s not really doing much. best guess is that after a week, there won’t be much of an effect on E2. Rebalancing of the homonal system as a whole may take a bit longer. I’d let it go 2 weeks at the least before spending money on tests.

When did you plan your next tests?

Finasteride has a much shorter half life of around five to 6 hours in men 18 to 60 years of age and up to 8 hours in over the age of 70 or in guys with liver disease. So, in about 36 hours, it’s pretty much out of your system. The finasteride fear mongers would argue much longer, but that’s off topic.

Curious, are you taking finasteride for hair loss or for BPH?

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I have the test kit ready, I was going to do it in about 3 weeks but I’m thinking to change my protocol now

I didn’t realise finasteride would affect my blood test, how would it?

I just started experimenting with it for hair loss prevention/regrowth, I’m thinking about adding or switching to ru58841 because I saw Dereks before and after pictures

It blocks conversion of T to DHT. That means more T, which can spill over to E2. However, with such a shot half life, I’d not be overly concerned about the finasteride affecting lab results as I would be the anastrozole which has a longer half life.

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I’m getting better results since I had the ai