Another study presented at the recent American Urological Association Conference found that over the time period studied mean testosterone levels fell by 25%. A news article explains:
"From 1999 to 2016, testosterone levels have declined in adolescent and young adult men (AYA), according to results presented at the 2020 American Urological Association Virtual Experience.
"Testosterone deficiency has a prevalence of 10%-40% among adult males, and 20% among AYA men aged 15-39 years, he added. Therefore, Lokeshwar and colleagues hypothesized that serum total testosterone levels will decline in AYA men.
"The investigators used data from the National Health and Nutrition Examination Surveys (NHANES) from 1999 to 2016 to analyze serum testosterone level changes over time in 4045 AYA males. During the study periods, 3 different assays (Biotin-Streptavidin from 1999-2004, IS-Liquid Chromatography from 2011-2012, and High-Performance-Liquid-Chromatography Tandem Mass Spectrometry from 2013 onwards) were used. However, of note, they demonstrate comparable testosterone values with only some additional accuracy in the latest modality, Lokeshwar said.
"After controlling for confounders—including year of study, age, race, BMI, comorbidity status, alcohol and smoking use, and level of physical activity—total testosterone was lower among men in the later (2011-2016) versus earlier (1999-2000) cycles (P < 0.001). Mean total testosterone decreased from 1999-2000 (605.39 ng/dL), 2003-2004 (567.44 ng/dL), 2011-2012 (424.96 ng/dL), 2013-2014 (431.76 ng/dL), and 2015-2016 (451.22 ng/dL; all P < .0001).
"Elevated BMI was associated with reduced total testosterone levels (P < .0001), with the mean BMI increasing from 25.83 in 1999-2000, to 27.96 in 2015-2016 (P = 0.0006). Lokeshwar noted that even men with a normal BMI (18.5-24.9) had declining total testosterone levels (P < .05) during the same time frames."
"From 1999 to 2016, testosterone levels have declined in adolescent and young adult men (AYA), according to results presented at the 2020 American Urological Association Virtual Experience.
"Testosterone deficiency has a prevalence of 10%-40% among adult males, and 20% among AYA men aged 15-39 years, he added. Therefore, Lokeshwar and colleagues hypothesized that serum total testosterone levels will decline in AYA men.
"The investigators used data from the National Health and Nutrition Examination Surveys (NHANES) from 1999 to 2016 to analyze serum testosterone level changes over time in 4045 AYA males. During the study periods, 3 different assays (Biotin-Streptavidin from 1999-2004, IS-Liquid Chromatography from 2011-2012, and High-Performance-Liquid-Chromatography Tandem Mass Spectrometry from 2013 onwards) were used. However, of note, they demonstrate comparable testosterone values with only some additional accuracy in the latest modality, Lokeshwar said.
"After controlling for confounders—including year of study, age, race, BMI, comorbidity status, alcohol and smoking use, and level of physical activity—total testosterone was lower among men in the later (2011-2016) versus earlier (1999-2000) cycles (P < 0.001). Mean total testosterone decreased from 1999-2000 (605.39 ng/dL), 2003-2004 (567.44 ng/dL), 2011-2012 (424.96 ng/dL), 2013-2014 (431.76 ng/dL), and 2015-2016 (451.22 ng/dL; all P < .0001).
"Elevated BMI was associated with reduced total testosterone levels (P < .0001), with the mean BMI increasing from 25.83 in 1999-2000, to 27.96 in 2015-2016 (P = 0.0006). Lokeshwar noted that even men with a normal BMI (18.5-24.9) had declining total testosterone levels (P < .05) during the same time frames."