[Total and free testosterone in the male depending on body weight (author's transl)]

Total testosterone, the fraction of unbound testosterone and free testosterone were measured in 116 males of varying body weight in the range of 80 to 256% of the ideal weight. There are 3 groups for the establishment of normal ranges of testosterone. Testosterone and the fraction of unbound testosterone were fairly constant in group I (80--160% of the ideal weight). In group II (160--200% of ideal weight) there was a tendency towards lower values. The relatively wide normal range for testosterone was not reached in only 5 of these 20 patients. In contrast, in group III (more than 200% of ideal weight) clear-cut changes of total testosterone were demonstable reaching only 38% (P less than 0.001) of control values. Changes were also clear for unbound testosterone which increased from 2.24 to 3.9% (P less than 0.001). The concentration of free testosterone decreased to a lesser extent (P less than 0.01). Despite the low total testosterone hypogaonadism was not demonstable clinically in the extremely obsese patients. According to these results "normal values" for total testosterone, the fraction of unbound testosterone and free testosterone could be established depending on body weight.