Hi Andy, a DHT blood test is a fairly unusual step. We would recommend you speak to a hair loss specialist first to get a free diagnosis of your scalp and hair loss conditions. It could be the case that there is an underlying medical condition that is causing your thinning as well as your scalp problems. Sebderm can also cause the hair to become weakened and prone to breakage if it makes you scratch your head a lot. If the follicles are being destroyed by DHT, this is a case of genetic hair loss ( male pattern baldness ) and that can be diagnosed without having to get your DHT levels tested. It is nothing to do with the oil in your scalp - these are actually healthy and help to keep the scalp moisturised. If you would like to understand more about your scalp and hair loss issues, please contact us or complete an Online Consultation form .