I have been taking finasteride for 7 years, 5mg/day as prescribed for BPH. During that period my Total T ranged from the low 300s to as high as 586 ng/dl. Free T however was usually low, ranging from 6 to 17 pg/ml. My last reading of 5.8 is below the LabCorp reference range of 7.2 to 24.0 pg/ml. With that, plus having most of the common low-T symptoms, I have met with a doctor that is also a bodybuilder and runs an anti-aging clinic.
I have never been able to get a satisfactory answer from my urologist or my PCP regarding the effect of finasteride on T levels. Neither Dr. was interested in spending time reviewing my hormones status since BPH has been well-controlled (PSA <1.2) and Total T was never below the LabCorp reference range until now. I forgot to ask about it in my initial consultation with the TRT Dr. and he didn’t mention it.
Finasteride does prevent conversion of T to DHT at least in the prostate and in the hair follicles. Some of the threads on this site mention that finasteride is problematic, but don’t really explain why.