In a nutshell, if you draw a line from your total testosterone on the left side of the plot over to your SHBG on the right side of the plot, that line will intersect the central curve at your calculated free testosterone value.
I’m interested if anyone can explain why the typical lab reference ranges for free testosterone are so low compared to the values on this chart. For example, I looked at my lab work and the ranges used are 25-80 pmol/L. If I look on the nomogram above, this range is so low on the central curve it can’t be reconciled with typical total testosterone and SHBG levels.
Any insight is appreciated.
PS: The color lines all over the nomogram have nothing to do with this question. This is just the best picture of a related nomogram I happened to find.