Obtaining a total testosterone
Peak blood level and a Trough blood level is useful.
The Peak for Testosterone Enanthate
is about 24-48 hours after the injection.
The Trough (lowest level) for Testosterone Enanthate is just before the next injection.
Obtaining both levels will give the range of testosterone one's body is exposed to.
This is helpful to see if a person is within a good therapeutic range.
The shorter the intervals between injections, the flatter the range will be.
Large variations between the peak and trough can be a problem because there can be large changes in DHT
and Estradiol levels - contributing to problems such as weight gain, acne, hair loss
, and hot flashes. Hot flashes occur when estradiol levels drop quickly - they are withdrawal from estrogen.
Large peaks of testosterone may also result in large amounts of DHT
and Estradiol being made. When Estradiol is made from testosterone, its peak levels last much longer than testosterone itself - resulting in a larger exposure to estradiol even as the levels of testosterone drop.
Testosterone Enanthate usually has a half-life of about 7-9 days. This results in a good total testosterone level (e.g. 700-900) at a dose of 100 mg a week. The half-life varies though depending on the person's ability to metabolize testosterone enanthate and testosterone.
In some men, the half-life of Testosterone Enanthate is much shorter. For example, in some men, the half-life is around 4 days. To achieve a total testosterone of around 800, such a person would need about 200 mg a week.
Given a Testosterone Enanthate dose of 200 mg every 2 weeks for an average hypogonadal male, the total testosterone curve shows a peak of around 1250 ng/dl approximately 24-48 hours after the injection, 1000 ng/dl around 4 days after the injection, 800 ng/dl 7 days after the injection, 600 ng/dl 10 days after the injection, and baseline about 14 days after the injection.
A way to tell what the half-life would be is to give the person a 200 mg dose then measure the total testosterone approximately 4 days or 7 days later. If the level is significantly lower than the average male dose curve, then the half-life is going to be shorter.
For example, I have a patient with a level of about 600 ng/dl 4 days after the 200 mg injection. This is about 40% less than the expected 1000 ng/dl seen in an average person. He has a very short half-life for testosterone enanthate. One could argue that his half-life is about 3 days (since 600 ng/dl is about half of the peak of 1250 ng/dl 24 hours after the injection). His body quickly destroys testosterone. He needed a 200 mg a week dose to achieve a trough blood level of about 800 ng/dl. It was best to dose this 100 mg twice a week to maintain an even blood level, avoiding a roller coaster effect, given the very short half-life of testosterone and testosterone enanthate in his body.