To answer you question - I agree with Dr Weiner, my concentration is between 5-6 times the normal platelet concentration. The amount of blood needed will be dependent on the surface area one is treating. Given the large surface area, I do recommend a test patch first to see how you respond. It only makes sense to see how good you respond to this procedure in a small area, rather than treating a large area.
Old stretch marks are harder to treat- my preferred option for old, white, silvery- papery stretch marks is a combination of CO2 fractional laser, or with INFINI RF and PRP. I also use Fraxel ReStore 1550, and also lasers in the 1540 wavelength. Of all the methods I find microneedling with RF energy and PRP the best, as it has the lowest rate of skin colour changes, and the fastest healing time. Results wise, it outperforms CO2 laser!
The truth is that stretch mark treatments are HIGHLY variable, depending on your own immune system, your skin type and the age of the stretch marks. Some get a 30% improvement, others up to 80%. An assessment is the very first step
Dr Davin Lim, Laser and aesthetic dermatologist.
This is a very important question. Please read the link. In short, most advertised PRP is not very concentrated. The ideal concentration is 6X normal platelet concentration which is 1.5 million platelets per ml. My machine requires 60cc to make 8cc. Any machine that draws 10cc will get you less than 2cc of the concentrated PRP. So to do a large surface area with 6X PRP, you need a lot of blood being drawn and the proper PRP kit. The Magellan TruPRP is my recommendation and I would draw 180cc. It is not cost effective to use many of the other machines nor are they going to get you the right platelet concentration. Remember that you can't draw much more than 180cc without really feeling the effects of the blood loss. Consider adding Infini for stretch mark correction