When I'm speaking of T metabolites, I'm talking of the big two: estradiol (E2) and dihydrotestosterone (DHT). When your body gets testosterone, whether it's endogenous or exogenous (from TRT), some of this T is converted to E2, some to DHT, some to other negligible metabolites, and the remainder stays as T.
As you can see, DHT and E2 each have their own effects on different aspects of the body. DHT is about skin and prostate, and E2 is about hair, brain, and bone. This is why when you have high DHT you have oily skin and (at highest levels) bachne and even male pattern baldness (although there are virtually no anecdotal reports of anyone going bald from TRT). Importantly, E2 levels influence how you think and feel mentally, as well as fatigue and energy. Low E2 typically means fatigue and sluggishness, and at lowest levels osteoporosis or temporary joint problems; high E2 can mean insomnia and brain fog.
An extremely important part about being on TRT, or on any form of medicinal therapy, is paying attention to your body. Your symptoms can be traced back to likely blood levels of certain hormones. All guys on TRT who are attentive enough know that blood results are secondary to symptoms in diagnosing whether their E2 levels are too low or too high, although sometimes it can be tricky. The reason this is the case is that lab values and norms for any hormone you can imagine are the result of very important population studies, and population studies look at averages and standard deviations and ranges and all sorts of other stats stuff regarding a group and not particular data points
. What's normal for one person might be on the high end of a cutoff range for one person and on the lower end for another; so a good E2 level with no symptoms and maximal functioning might be 22 pg/ml for one person, 30 for another, and 18 for another. I'm currently going through slightly low E2 levels, and for me I experience insomnia if my levels are too high, leading to daytime fatigue secondary to sleep issues. Because the secondary fatigue of high E2 is similar to the general primary fatigue and drowsiness of low E2, it's hard to tell by this fatigue symptom alone if E2 levels are too low or high. Which is why I do a mental checklist for other high or low E2 symptoms, and I tend to start by knocking off high E2 to see if low E2 could be the case. Do I have bloating? Nope. Water retention? Nope. Am I feel more fatigued or foggy headed? More fatigued. These and other sometimes subtle hints tell me I'm currently low E2. A recent bloodtest revealed my levels were borderline, and we all know that tests have some degree of potential for invalidity, reliability, and lab error. So it's especially important when blood results are borderline to consider your symptoms.
Anyways, a clever way to control E2 is through 1) the method of administration for cypionate (or enanthate or propionate or whatever, but I'm sticking with C for this thread), whether intramuscular (IM) or subcutaneous (subq), and 2) the injection schedule you use, whether once per two weeks, once per week, every three days (E3D), every other day (EOD), or even every day. So here's a formula you can consider for ideal metabolite (E2, DHT) and T control:Total T = T metabolites (E2, DHT) = injection method X injection schedule
That is, the amount of total T you have in your body from exogenous (injectible) testosterone will mirror the amount of T metabolites you have, both of which are determined by the injection method you use in relation to the schedule you have for the method you use. There are a few different combinations, but these are the most popular:
IM + once every two weeks
subq + once every two weeks
IM + once per week
subq + once per week
IM + every three days
subq + every three days
IM + every other day
subq + every other day
Other schedules include once every five days or every ten days. You could theoretically do it by the hour, e.g., a very small dose IM or subq every 12 hours, but nobody got time for that, and the law of diminishing returns just makes this unreasonable.
The big point here is: you need to play with each of the schedules above to find what works for you
. And here's a hint: once every two weeks, unless you have extremely high SHBG (more on this in a bit), won't work for you IM or subq, although it could. The ridiculous reasoning endos and other docs give for why injectible TRT supposedly "fails" is because their criteria for success is solely once every two weeks IM. Almost everyone is going to "fail" with this method and schedule: levels will shoot up way too high the first 1-2 days, causing a skyrocketing level of E2 and DHT (leading to symptoms of high levels for both), and then drop down to low levels by the time of the next injection, leading many guys to return to hypogonadal levels again before they pull another IM injection. And while we're at it, here's another hint: almost every single person I've read about or talked with has preferred subq over IM. No aspirating, lower E2/DHT rises (DHT rises high particularly with gels, but not with subq, given that 5-alpha-reductase is concentrated in the skin and not fat, so if you're going subq make sure you're injecting deeply into the fat), flatter levels of T with lower peaks and higher troughs.
Another point: there are many combinations of schedule and method to determine variations in T and metabolites
. If I was to include the type of injectible testosterone (e.g., propionate, etc.), that would be another variable to add to the formula. If you want to control how high or low your E2 level is, you'll do this through method and schedule. Given that E2 tends to "come down" considerably more slowly than T after an injection (or it stays up longer), if you want to keep your E2 levels a bit high, you'll want to add a day or two to your schedule, regardless of method: going from EOD to E3D will mean potentially a 50% increase in E2 (this isn't an entirely accurate calculation, given that individual doses of T don't determine overall levels given the accumulation of this substance over time, but something to consider for the sake of this discussion), plus or minus slight fluctuations around this average number. If you have an average E2 of 17 and you're feeling fatigued or sleepy on an EOD schedule, you could then consider going E3D, which would give your E2 a higher average of around 25 or so.
And here's an important point for the stats nerds: we have to consider the mean (average) and standard deviation (or how much a given data point of E2 at any time varies from the mean) when thinking of T levels and associated metabolites, in that the longer the injection schedule (every five days rather than every other day), the higher the mean or average but also the higher the standard deviation or how much E2 fluctuates from the mean given the number of days between injections.
Translation: you have more fluctuation room for E2 if you have a longer schedule, and less fluctuation room for a smaller schedule, although with the former you'll have a higher overall or average E2. Make sense?
And there's yet another variable I'll briefly discuss that determines which schedule is best for you, and especially whether subq is more or less a requirement: sex hormone binding globulin (SHBG). The short of it is that SHBG determines how quickly or slowly your T levels shoot up after an injection: someone with low SHBG would spike higher and drop more quickly, and someone with high SHBG would spike and peak more slowly and drop more slowly as well, but you would need to inject more T to get the same effect (in general, but a likely exception to this is the variation of yet another hormonal variable, DHEA, with higher levels of this hormone causing more T and E2 after an injection, but there's no room for this interesting discussion). So maybe we could put it all together thusly:Total T = T metabolites (E2, DHT) = injection method X injection schedule X SHBG
Or something like that.
It took me five months to find a method and schedule that works for me, and I'm still tweaking given a pleasant surprise of how low subcutaneous injections got my E2 compared to IM. But if I could go back and do it all over again, I would have saved a lot of time (literally months) and pointless symptoms of high or low E2 or DHT if I could have just started subq E3D. But you don't have to make this mistake because your doctor doesn't know how to extract very basic pharmacokinetics data from cypionate or other esters they should but probably aren't even aware of to begin with to how things would jive if you were to adjust the variables mentioned in the formula above.
The biggest point of all is that this is just basic math, and knowing the values to plug in for the formula (whether we take the one above literally or not) gives you an incredible amount of control over your symptoms, and therefore symptom relief. Add this to paying for your own labs and the docs can all go jump in the lake.