Free Testosterone, Percent Low

[MAD King]

Hello,

I received my blood test results back.
I am age 60, 5'72, 158 lbs, non smoker, non drinker, active and eat healthy, but some of my blood test results are very low.

Free Testosterone, Percent is 1.52 (Range 1.60-2.90 %). I could not find anything about that.
Everything else is within range:

Sex Hormone Binding Globulin (SHBG)	57.0 19.3-76.4 nmol/L
Testosterone Total	660.00 264.00-916.00 ng/dL
Testosterone Bioavailable	235 131-682 ng/dL
Free Testosterone (calculation)	100 47-244 pg/mL

Also, my vitamin D level is low too:

Vitamin D 25-Hydroxy

19.2 L 30.0-100.0 ng/mL

I am not sure if this is related to the Free Testosterone. Could also not find anything about the relation.