What causes low free test?

[jj341]

My total T is 410 on a reference range of 241-827 and my free test is 10.31 on a reference range of 8.69-54.69. I have the symptoms of low test.
I'm 62 years old, 5'11", 175lbs. 18% BF and in relatively good shape. I work out regularly. What can cause the low free test I have? It's at the bottom of the scale. Thanks guys.

 

[sLd]

A lot of factors but as far as I know , it goes down by age , older you are lower test you have. Also genetic has prolly a lot to do with it. bad recovery after cycle etc.