This is a very good question Owen and one that more doc’s should ask them self’s before writing a script for T- supps.
For the sake of my fingers I will refer from here forth Testosterone will be Just “T”
I’m also not going to go into what it does only how it shows on tests and what effects it has on the readings.
T is produced in the Gonads of the male and the ovaries of the female during the reproductive years it will higher in both sexes and will decline with age. The T producers release it directly into the blood stream where it circulates freely through out the body as a lipid similar to cholesterol.
However it’s a useless item until it binds with a protein known as “Sex Hormone Binding Globin.” SHBG for short. On the blood test this bound substance is known as Serum Testosterone, Serum meaning the liquid faction of the blood once it is bound it becomes able to exist in the watery fluid otherwise the liver would filter it out.
However at this point, It is another basically useless item but the T takes on a different form while attached and when it breaks loose it is the effective cell enhancing substance, protein converting T the body needs. This substance is referred to on the blood test as Free Testosterone. The normal ratio is approx. 5 to 1.
I think you can see if the liver is not producing enough SHBG these levels will be low. So Low SHBG will equal Low T in the blood readings.
But the saliva test gives you an idea what is freely available ready for binding. In other words the organs are producing enough or more then is needed but without binding and separating it will be just shuttled out. The body is smart it says hay where’s my T dose and the liver will not release it and the levels of free will rise in hopes of getting the useable substance going. In another part of the liver where the SHBG is produced is dealing with a crisis of their own their getting bombarded with sugar and can’t get their production up to the demands of the body so they just do their best which is usually low so in the body T levels are down. I broke into this analogy for clarity and understanding. So now lets act like a doc. Your Blood T levels are low let’s add more free T and you should be alright. See the problem here??? Now the liver see excess free T levels and goes into dump mode. So I think you can see why a blood and saliva test together gives the true picture here. In your case your supplying more then enough free T it just not getting converted to the form your body can use. Get the sugar levels down and BOING!! I’ll leave it at that.