Phil Goodman
Well-Known Member
Prompt using Claude:
I’d like to compare various protocols of trt. For an average 200 lb man, review the literature to make a best guess about what his total testosterone blood levels would be for the following doses.
50 mg testosterone cypionate once per week
25 mg testosterone cypionate twice per week
100 mg testosterone cypionate once per week
50 mg testosterone cypionate twice per week
Take your time and confirm accuracy before responding
Response from Claude:
Good, I now have solid data. Let me synthesize this carefully using the pharmacokinetic literature and the key anchor points from clinical studies.
Here’s a thorough breakdown based on the published literature. I’ll note upfront that the exact numbers in this kind of analysis depend on baseline endogenous production (assumed to be suppressed at steady-state), individual metabolism, SHBG levels, body composition, and whether injections are intramuscular or subcutaneous. The figures below represent reasonable population averages at steady state, with typical ranges reflecting real inter-individual variation.
Key pharmacokinetic anchors from the literature
The half-life of testosterone cypionate when injected intramuscularly is approximately eight days. This means at steady state (roughly 5 half-lives, or 5–6 weeks of consistent dosing), drug accumulates meaningfully between doses. Importantly, intramuscular administration of 200 mg of testosterone cypionate produced a mean supratherapeutic Cmax of 1,122 ng/dL occurring 4–5 days post-injection. That’s a well-established anchor for scaling.
In a clinical study of hypogonadal men treated with IM testosterone cypionate 100 mg weekly, trough total testosterone rose from a baseline of ~314 ng/dL to ~536 ng/dL post-treatment. That trough figure is key for calibrating the 100 mg/week once-weekly protocol.
The pharmacokinetics are essentially linear and dose-proportional at TRT doses, so the numbers below scale accordingly.
Protocol Comparisons (at steady state, average 200 lb man)
1. 50 mg testosterone cypionate once per week
∙ Weekly total dose: 50 mg
∙ Peak (day 2–3): ~400–500 ng/dL
∙ Trough (day 6–7, pre-injection): ~250–350 ng/dL
∙ Average/mid-week: ~350–420 ng/dL
∙ Peak-to-trough swing: moderate (~150–200 ng/dL fluctuation)
This is a low-dose protocol. Many men will land in the low-normal range and may hover near or below the 300 ng/dL threshold by injection day. It’s a reasonable starting/conservative protocol but may leave some men symptomatic near trough.
2. 25 mg testosterone cypionate twice per week (same 50 mg/week total)
∙ Weekly total dose: 50 mg (same as above)
∙ Peak (day 1–2 after each injection): ~350–430 ng/dL
∙ Trough (day 3–4, pre-injection): ~280–360 ng/dL
∙ Average: ~350–420 ng/dL
∙ Peak-to-trough swing: much smaller (~70–100 ng/dL fluctuation)
Because the total weekly dose is identical, the average level is essentially the same as Protocol 1. The key difference is dramatically improved stability — the shorter dosing interval relative to the half-life keeps levels far more consistent. The cypionate half-life of ~8 days means 25 mg every 3.5 days produces very smooth, near-flat kinetics. This is arguably the most physiologically stable low-dose option.
3. 100 mg testosterone cypionate once per week
∙ Weekly total dose: 100 mg
∙ Peak (day 2–3): ~700–900 ng/dL
∙ Trough (day 6–7, pre-injection): ~450–550 ng/dL
∙ Average/mid-week: ~550–700 ng/dL
∙ Peak-to-trough swing: significant (~300–400 ng/dL fluctuation)
This is the most commonly studied standard TRT dose. Clinical data from men on 100 mg IM-TC weekly showed trough levels reaching ~536 ng/dL , which aligns well with this estimate. The Endocrine Society Clinical Practice Guidelines target a therapeutic level of 400–700 ng/dL measured one week after a dose of TC. Once-weekly dosing at this amount produces meaningful peaks and troughs — some men feel the difference.
4. 50 mg testosterone cypionate twice per week (same 100 mg/week total)
∙ Weekly total dose: 100 mg (same as above)
∙ Peak (day 1–2 after each injection): ~600–750 ng/dL
∙ Trough (day 3–4, pre-injection): ~500–650 ng/dL
∙ Average: ~550–700 ng/dL
∙ Peak-to-trough swing: much smaller (~100–150 ng/dL fluctuation)
Again, the average testosterone exposure is identical to Protocol 3, but the curve is dramatically flatter. Splitting doses to 50 mg twice weekly is specifically recommended to avoid the high peaks and troughs seen with less frequent injections. This is widely considered the “gold standard” TRT protocol among endocrinologists for stable symptom management, lower estradiol peaks, and reduced hematocrit elevation.
Important caveats
∙ These are population averages. Individual variation is substantial — SHBG, body fat, metabolic rate, injection site, and whether injection is IM vs. subcutaneous all shift results meaningfully.
∙ Subcutaneous injection of the same dose tends to produce slightly lower, smoother peaks than IM.
∙ Endogenous production is assumed to be largely suppressed at steady state, which typically occurs by weeks 5–6.
∙ A 200 lb man’s weight has a modest effect on distribution volume, but the PK modeling literature suggests weight is not a major driver of average levels at these doses — the effect is smaller than most people assume.
∙ Real blood work is irreplaceable. These estimates are useful for protocol planning but not for replacing lab monitoring.
I’d like to compare various protocols of trt. For an average 200 lb man, review the literature to make a best guess about what his total testosterone blood levels would be for the following doses.
50 mg testosterone cypionate once per week
25 mg testosterone cypionate twice per week
100 mg testosterone cypionate once per week
50 mg testosterone cypionate twice per week
Take your time and confirm accuracy before responding
Response from Claude:
Good, I now have solid data. Let me synthesize this carefully using the pharmacokinetic literature and the key anchor points from clinical studies.
Here’s a thorough breakdown based on the published literature. I’ll note upfront that the exact numbers in this kind of analysis depend on baseline endogenous production (assumed to be suppressed at steady-state), individual metabolism, SHBG levels, body composition, and whether injections are intramuscular or subcutaneous. The figures below represent reasonable population averages at steady state, with typical ranges reflecting real inter-individual variation.
Key pharmacokinetic anchors from the literature
The half-life of testosterone cypionate when injected intramuscularly is approximately eight days. This means at steady state (roughly 5 half-lives, or 5–6 weeks of consistent dosing), drug accumulates meaningfully between doses. Importantly, intramuscular administration of 200 mg of testosterone cypionate produced a mean supratherapeutic Cmax of 1,122 ng/dL occurring 4–5 days post-injection. That’s a well-established anchor for scaling.
In a clinical study of hypogonadal men treated with IM testosterone cypionate 100 mg weekly, trough total testosterone rose from a baseline of ~314 ng/dL to ~536 ng/dL post-treatment. That trough figure is key for calibrating the 100 mg/week once-weekly protocol.
The pharmacokinetics are essentially linear and dose-proportional at TRT doses, so the numbers below scale accordingly.
Protocol Comparisons (at steady state, average 200 lb man)
1. 50 mg testosterone cypionate once per week
∙ Weekly total dose: 50 mg
∙ Peak (day 2–3): ~400–500 ng/dL
∙ Trough (day 6–7, pre-injection): ~250–350 ng/dL
∙ Average/mid-week: ~350–420 ng/dL
∙ Peak-to-trough swing: moderate (~150–200 ng/dL fluctuation)
This is a low-dose protocol. Many men will land in the low-normal range and may hover near or below the 300 ng/dL threshold by injection day. It’s a reasonable starting/conservative protocol but may leave some men symptomatic near trough.
2. 25 mg testosterone cypionate twice per week (same 50 mg/week total)
∙ Weekly total dose: 50 mg (same as above)
∙ Peak (day 1–2 after each injection): ~350–430 ng/dL
∙ Trough (day 3–4, pre-injection): ~280–360 ng/dL
∙ Average: ~350–420 ng/dL
∙ Peak-to-trough swing: much smaller (~70–100 ng/dL fluctuation)
Because the total weekly dose is identical, the average level is essentially the same as Protocol 1. The key difference is dramatically improved stability — the shorter dosing interval relative to the half-life keeps levels far more consistent. The cypionate half-life of ~8 days means 25 mg every 3.5 days produces very smooth, near-flat kinetics. This is arguably the most physiologically stable low-dose option.
3. 100 mg testosterone cypionate once per week
∙ Weekly total dose: 100 mg
∙ Peak (day 2–3): ~700–900 ng/dL
∙ Trough (day 6–7, pre-injection): ~450–550 ng/dL
∙ Average/mid-week: ~550–700 ng/dL
∙ Peak-to-trough swing: significant (~300–400 ng/dL fluctuation)
This is the most commonly studied standard TRT dose. Clinical data from men on 100 mg IM-TC weekly showed trough levels reaching ~536 ng/dL , which aligns well with this estimate. The Endocrine Society Clinical Practice Guidelines target a therapeutic level of 400–700 ng/dL measured one week after a dose of TC. Once-weekly dosing at this amount produces meaningful peaks and troughs — some men feel the difference.
4. 50 mg testosterone cypionate twice per week (same 100 mg/week total)
∙ Weekly total dose: 100 mg (same as above)
∙ Peak (day 1–2 after each injection): ~600–750 ng/dL
∙ Trough (day 3–4, pre-injection): ~500–650 ng/dL
∙ Average: ~550–700 ng/dL
∙ Peak-to-trough swing: much smaller (~100–150 ng/dL fluctuation)
Again, the average testosterone exposure is identical to Protocol 3, but the curve is dramatically flatter. Splitting doses to 50 mg twice weekly is specifically recommended to avoid the high peaks and troughs seen with less frequent injections. This is widely considered the “gold standard” TRT protocol among endocrinologists for stable symptom management, lower estradiol peaks, and reduced hematocrit elevation.
Important caveats
∙ These are population averages. Individual variation is substantial — SHBG, body fat, metabolic rate, injection site, and whether injection is IM vs. subcutaneous all shift results meaningfully.
∙ Subcutaneous injection of the same dose tends to produce slightly lower, smoother peaks than IM.
∙ Endogenous production is assumed to be largely suppressed at steady state, which typically occurs by weeks 5–6.
∙ A 200 lb man’s weight has a modest effect on distribution volume, but the PK modeling literature suggests weight is not a major driver of average levels at these doses — the effect is smaller than most people assume.
∙ Real blood work is irreplaceable. These estimates are useful for protocol planning but not for replacing lab monitoring.
