Scalp DHT vs Serum DHT

What is the difference between scalp DHT and serum DHT? Avodart reduces scalp DHT by 55% and serum DHT by 92% what does that mean? How does that impact the hair?

Yes, it is true that Avodart (dutasteride) inhibits 92% serum DHT and 55% scalp DHT — and Propecia (finasteride) inhibits 70% serum DHT and 38% scalp DHT (see study). I hear the terminology of scalp DHT and serum DHT every once in a while, but I really don’t know how significant they are. You would think that lowering scalp DHT is better than lowering serum DHT, but one flows to the other starting off in the serum.

So while Avodart has been proven to be more effective than Propecia in inhibiting serum DHT and scalp DHT, Avodart actually has more short and long term side effects than Propecia. For example, there is a worry about sterility (not common but present) with Avodart, something that should worry the young man.