Where to get a blood test / dermatologist specialising in hair in London?

[FM1]

I have finally decide to get a blood test done to determine what is causing my hair loss but I'm not too sure where to start. Can a dermatologist do this or do I need to go to my GP? If it is a dermatologist, can someone recommend a good one in London?

Thanks in advance.

 

[Dench57]

What makes you think it isn't plain old male pattern baldness?

 

[hamish.baroube]

Following.