However, the bigger point of the study was that when measured 4 times over the course of 166 days (with 2-3 weeks separating the 1st from the 2nd draw and the 3rd from the 4th), morning TT varied by an average of 118ng/dL. Interestingly, if TT was averaged between the 1st & 2nd values and then compared to the average of the 3rd & 4th values, the variability decreased to just 66ng/dL.
Moreover, of these 96 overweight men w/symptomatic hypogonadism, only 5 had a TT <230ng/dL at any time during the year and only one of these 5 had TT <230ng/dL throughout the year. Of 25 men w/TT <288ng/dL at any time during the year, only one (that same person) had TT <288nd/dL throughout the year. And of 48 men w/TT < 345ng/dL at any time during the year, only 10 had TT persistently <345ng/dL throughout the year. So does it really make sense to artificially place the threshold for declaring laboratory-defined hypogonadism at <230ng/dL vs <288ng/dL vs <345ng/dL?
Despite all being clinically hypogonadal, 35 men had an initial TT >432ng/dL. Just under half of these men subsequently had a repeat TT <432ng/dL, only 2 of whom had a TT <288ng/dL. Thus, the authors noted that those who initially measured on the higher end of the range were less likely to measure low whereas those who measured low initially were more likely to measure (relatively) higher upon repeated testing. Think of this as regression toward the mean.
But let's take a step back and think about this study in light of this Monday's post regarding the range obtained from healthy non-obese 19-40yo men: 348-1,099ng/dL w/an average of 724ng/dL. Granted this range was obtained using a different laboratory technique so it's nigh impossible to compare apples to oranges. The fact remains that these 96 men were clinically hypogonadal. In other words, they reported any combination of cognitive dysfunction, dysthymia/depression, erectile dysfunction, decrease in sex drive, loss of energy, loss of muscle mass despite exercise, inability to lose fat despite proper nutrition, and more.
Battle of Bunker Hill here!