I scanned the study quickly:
A prospective clinical study including patients diagnosed with Androgenetic Alopecia was designed. MD was performed with 1 mL of intradermal dutasteride 0.01% injections (dutasteride 0.01%, Mesotherapy Worldwide, Australia) through 6 months with a one-session treatment every three months; a total of three sessions.
This means that they injected the patients at the month 0, month 3 and month 6, right...
Assessment of the response was done 9 months after the first injection by three dermatologists who evaluated the degree of improvement as follows: −1 = worsening, 0 = no change, 1 = improvement. To evaluate the safety of the therapy, a strict surveillance for adverse effects was done. In addition, laboratory investigations (total and free testosterone, 5-alpha-dihydritestosterone, and 3-alpha-androstanediol glucuronide) were performed before and after treatment to analyse if the treatment produced any systemic hormonal modification. Statistical analysis with the Wilcoxon signed-rank test was performed to detect significance between laboratory results.
However the assessment was done 9 months after. There is no clear mention on when they did the laboratory investigations, only the mention of "performed before and after treatment".
That is not concrete. If the laboratory investigations are done at 9 months it is totally expected there would be no systemic hormonal modification.
But honestly even if the laboratory investigations were done at 6 months it doesn't exactly mean that there was no systemic hormonal modification over the course of these treatments. It just means that at that time point there was no (significant) hormonal modification in comparison with before the treatment.
To illustrate this it might look like this:
You inject the patient on day 1, you measure blood serum levels after the injections on day 1 or day 2. You see no hormonal modifications.
Now you wait another half week and you measure again, suddenly you see hormonal medications.
Since this is injected instead of orally ingested it is only expected that the concentration of dutasteride in serum takes longer and thus it takes longer before serum levels are affected.
Bottom line is, is that this study is severely limited and the study method is quite poor. So how does one even look further?