Can PRP delay/stop hair loss due to DHT

PRP does not affect DHT. Therefore, the best combinations are those which block DHT and are combined with PRP. Blockers of DHT include FDA-approved Propecia, off label dutasteride and progesterone. In summary, PRP can decrease or possibly prevent hair loss, however it does not do it by reducing DHT.
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Prp will improve hair growth, especially when combined with progesterone.  I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. Hair transplantation is an alternative. See an expert. Best, Dr. Emer

PRP(Platelet Rich Plasma) does not effect DHT levels.Its mechanism of action is felt to be through the release of various growth factors which influence follicular cell growth and death.It is felt that PRP will help keep hair in the active growth phase longer and possibly thicken up some of the "miniaturized " hairs.There is currently no standardization for the interval of treatments but it seems as if several weeks to several months is most effective.

PRP is a restorative regenerative treatment that improves the tissue it is injected into.  In the hair restoration field, it shows great improvement in healing post procedure and can also be used annually (depending on the method used) to reverse the aging process of follicles. 

Patients with genetic pattern hair loss (the form of hair loss that results from a genetic sensitivity to DHT) often exhibit a characteristic shrinking of the hair follicles. As the follicles shrink, they produce hair that is thinner and thinner until they reach a point where they stop producing hair at all. Injecting Platelet Rich Plasma into the scalp can cause the shrinking hair follicles to become healthier and larger, delaying hair loss and, in some cases, even producing thicker and fuller hair growth. Platelet rich plasma also accelerates the transition of the hair follicle from the dormant telogen state back to the actively growing anagen state, reducing the necessary recovery time after hair restoration surger
Platelet Rich Plasma has proven to be effective as a stand-alone treatment for men and women with other types of hair loss, like traction alopecia, alopecia areata, eyebrow hypotrichosis, and chronic telogen effluvium.  However, I always recommend that it be used in conjunction with other DHT blockers, like oral finasteride or blended topical treatments that contain finasteride or dutasteride. Patients undergoing platelet rich plasma therapy typically undergo a series of three initial treatments, six weeks apart followed by a repeat treatment one year after the first in order to achieve the best results. However every patient is unique, so I would recommend that you visit a doctor who is specialized in treating hair loss and who has also experience with platelet rich plasma therapy so that you can together formulate a treatment plan that fits your individual needs.

PRP used in conjunction with a topical like finasteride and Rogaine work well together as they help with hair loss through different pathways.

PRP appears to lengthen the anagen cycle or growing phase, and can increase hair shaft diameter and length.  It also has  numerous protein growth factors which stimulate hair growth, and may have an effect on stem cells in the hair bulb, dermal papilla.  DHT affects androgen receptors in the genetically sensitive follicles resulting in shortening the hair cycle, and progressive hair changes including thinner diameter, shorter length, and lighter in color ( less pigment).
It is unknown if PRP can prolong the long-term effects of DHT.  Only the class of DHT blockers like finasteride have clinical trials showing the beneficial effects over time.

Thank you for your question. You asked a question without a photo if PRP delays or stops the effect of DHT on hair, with a schedule of injections every 4-6 months.
I can help you understand this because DHT as the cause of hair loss is what most people are familiar with, so I can see why an interrelationship is assumed there. A little background: I’m a Board-certified cosmetic surgeon and Fellowship-trained oculofacial plastic and reconstructive surgeon. I have been in practice in Manhattan and Long Island for over 20 years. I am also the founder of TrichoStem™ Hair Regeneration Centers, which is based on a system we developed as a non-surgical alternative to hair transplant for men and women with thinning hair who come from around the world. We have a lot of experience with treating hair loss, and DHT, PRP and other modalities are offered and discussed every day, all day long in our practice.
DHT as a cause of hair loss was derived out of research that ultimately created the drug Propecia, or finasteride as the generic. DHT or dihydrotestosterone is converted testosterone by an enzyme called 5-alpha reductase. The effect of DHT is actually through circulation as it goes to the hair. To decrease DHT, you have to do it systematically - in other worlds, you have to take a pill. You have to take finasteride every day, which is only relevant for male pattern hair loss.
The causes of hair loss are very poorly understood, with the only awareness we have scientifically as a factor is dihydrotestosterone. However, it is clear dihydrotestosterone is not the only thing that’s causing hair loss. Only 60% of men will respond to finasteride, while 40% will not, so if you think about it, if DHT was the actual cause of all male pattern hair loss, it should be a 100%.
We had the opportunity to see the difference and distinction of what PRP does, as well as new material used for stem cell-based wound healing called Acellular matrix.
Understanding that PRP has multiple effects on the hair follicle mechanism, and recent studies and dermatologic research have shown different pathways which PRP can stimulate hair growth. However, PRP is not a DHT blocker, so you can improve the expression of hair loss by regular injections of PRP, but you are not doing anything specifically to DHT.
Several years ago when we were doing hair transplants, we tried an improved approach to get the donor area and hair grafts to heal better. It’s a challenge of hair transplants because grafts don’t always survive, and the donor area has a tendency to scar, especially with traditional strip approach. What was a serendipitous observation was thinning hair became thicker when we used platelet-rich plasma and Acellular matrix. Acellular matrix became something I felt I can work on to develop as a system to try to stimulate hair growth. With a lot of interesting challenges being overcome, we developed a system we call TrichoStem™ Hair Regeneration or Hair Regeneration. With this injection method, we’re able to  stop the progression of hair loss, reactivate hair that’s not growing, and induce the shed of thinning hairs so thicker hairs can grow in.
How is this different from PRP? I use PRP a lot in my practice to help people with acne scars, wrinkles, dark under eye circles, and all kinds of ways to improve skin quality and complexion. It has been my observation that PRP alone will only stimulate hair growth for short-term, and it doesn’t help with hair loss progression.
Our clinical experience with our method of Hair Regeneration, with a single injection, we are able to keep people from losing hair, and regain hair for the duration of 5 years for 99% of pattern hair loss patients, both men and women. We customize for each individual patient because people come with different degrees of hair loss and different genetics. I would say the stability of this procedure has been remarkable. Interestingly, because of a lot of fear about the long-term sexual side-effects of taking finasteride, we have been able to do this without the benefit of a DHT blocker. So what was essentially revealed through this development is there is more to hair loss than just DHT.
I support the concept that if someone can tolerate taking finasteride and do Hair Regeneration, there’s actually a synergistic benefit. We’ve had many patients who took finasteride before coming to us because they were still losing hair. They probably significantly slowed down their hair loss by using finasteride, but they were still losing hair. So taking finasteride alone was good, but when they did Hair Regeneration, they had more growth, had better outcome in terms of overall scalp coverage, and real significant improvement.
I would say the question of mechanism is not really valid, but the question of approach to maximizing and saving your hair, stopping hair from going away, and regrowing your hair is now an opportunity for you to further explore medical therapy, PRP, and the technology we developed, Hair Regeneration with PRP + Acellular matrix. Learn more about these, and hopefully you’ll find a solution that fits your lifestyle. I hope that was helpful, I wish you the best of luck, and thank you for your question.