Study: Testosterone Distribution in Lean Men 20-39 Years of Age Without Comorbidities

New paper from Oct 2019

Calculated ref range from the data presented in the study linked below is:
NHANES III 304 - 944 ng/dl
cont NHANES 348 - 1005 ng/dl

We used cross-sectional data for never-smoking, lean men ≥20 years without diabetes, myocardial infarction, congestive heart failure, stroke, or cancer, without use of hormone-influencing medications, and participated in morning sessions of National Health and Nutrition Examination Survey (NHANES) III (phase I 1988–1991) or continuous NHANES (1999–2004).
In NHANES III, in never-smoking, lean men without comorbidities, median (25th, 75th percentile) testosterone was 4% to 9% higher than all men—20 to 39 years: 6.24 (5.16, 7.51), 40 to 59: 5.37 (3.83, 6.49). In continuous NHANES, in never-smoking, lean men without comorbidities, levels were 13% to 24% higher than all men—20 to 39 years: 6.26 (5.32, 7.27), 40 to 59: 5.86 (4.91, 6.55), and ≥60: 4.22 (3.74, 5.73). In never-smoking, lean men without comorbidities, median estimated free testosterone was similar to (NHANES III) or slightly higher than (continuous NHANES) in all men.
Third, for quantitating testosterone concentration, we used the Elecsys Testosterone Immunoassay (Roche Diagnostics), which was FDA approved and in wide clinical use. The method was standardized by isotope dilution gas chromatography mass spectrometry [21].


Good info. Thanks

Thanks for posting that. Where did you get the calculated ranges? I didn’t see that in the study, did you calculate that yourself? It doesn’t look significantly different from what I’ve seen previously (300-1100 ng/dL).

The problem, from my perspective anyway, with the ranges is summed up in this paragraph:
“Clinical guidelines for men with hypogonadism due to conditions of the hypothalamus, pituitary, and testes, typically indicate that the target level during testosterone therapy is the age-specific lower range for eugonadal men. Given the possibility of adverse effects of testosterone therapy, targets for aging men are needed.”

As a man of a certain age shall we say, I’m not interested in the age-specific lower range for a eugonadal man. I’m interested in the range for a healthy, randy young bastard. LOL. Based on what I’m seeing in the study, that would appear to be around 700 ng/dL give or take. Actually, given that they used an age range of 20-39 and I noticed a small but distinct change in libido and sexual performance around age 27-28, I suspect that if they had split that into two groups of 18-25 and 26-39 or something like that, they would have detected a measurable difference between the two. At any rate, I see where this sets up a conflict in the average doctor/patient expectations for treatment if the doc is playing it safe and conservative and aiming for the lower end of the range for an older man while the patient wants to feel like he did when he was 20. I’d rather be healthy, strong, and vital and until I keel over at 70 than live to 85 but spend the last 25 years feeling older, weaker, and tireder and not having as much interest (or ability) in sex. It’s a matter of understanding, acknowledging, and weighing the risks and making an informed decision.

One can calculate the reference range (mean +/- 2 SD) from the provided data of the mean and the 25th and 75th percentile.

Yes thats what the say, but I am not so sure about that. In most clinical studies for example the target is set at the mean of the age specific range. And look around here, it seems rather easy to get your physicians ok to target any T level which provides symptom relief, even if its in the supraphysiological range.

100% agreed. If this is an informed decision than I think thats absolutely ok. Its about balancing benefits and risks.

The data on this on is quite conflicting. Some data suggest that T starts to decline already at the end of the 20s, while others show no decline until end of 30s.

The paper below for example suggests a different age related decline between black and white males. Who knows, it seems to be highly variable between individuals.

I think I must have been skipping out, drinking beer and shooting pool in the student union the day they covered that in class. LOL

I suspect the folks in this forum are not representative of the typical TRT patient. They tend to be far more informed and seek out doctors who will meet their needs and switch doctors if they and their doctor can’t come to agreement on treatment protocol. I asked my doctor and he aims for around 500 ng/dL. I asked him to up my dosage and he did but reluctantly and certainly not into supraphysiological range. I’m due for a lab test next week and expect to see something in the low 600s. I’m going to ask him to bump me up to the 700s. If he won’t I might have to seek out a new doctor. But if that is the guidance that they are being given then I could see why. Plus he doesn’t want to be sued if I have a heart attack or stoke however unlikely that might be.

Agreed, it’s highly variable between individuals. I can remember from my teens until I was dating this girl when I was 26 having a raging libido and wanting to sex any girl with a pulse. Then at 27 I started dating another girl and it just didn’t seem to have that quite the same urgency. I thought maybe I just wasn’t that into her but it never went back to the way it was before. My libido was still good, excellent even, but not like in my teens and early-mid 20s. It stayed pretty much that way until I hit 50 and then started a precipitous decline until by my mid-50s it was bad enough that I sought treatment. I was down to 303 ng/dL and had all the symptoms. Now things are back to “normal” - like they were in my 30’s and 40’s but not like in my teens and 20s. I wonder if it’s possible to get back to that level.

There may be no fountain of youth but honestly for the most part I haven’t noticed too many significant changes in my body or capabilities as I’ve gotten older. My hair is grayer (a little Just for Men can take care of that) and I need progressive lenses for my glasses. With the testosterone issue corrected I’m back in the gym and leaner and more muscular than I was in my 20s (I was 195-lbs @ 18%bf when I graduated Basic Training at 23 and I’m 200-lbs and 14.3%bf using the same Army method of determining body composition now - my neck is 1/2" bigger and my waist 1 1/2" smaller). My joints are stiffer. I might be almost as fast in a straight line but I’m nowhere near as agile so don’t expect me to change direction. LOL. And as luck would have it, my wife is on HRT as well and it appears to be working just as well for her so we can go at it pretty much the same as when we first met. I’m not ready for a rocking chair just yet.