The choice between single spin vs double spin PRP is usually presented to clinicians as a quality question — as though one protocol makes good platelet-rich plasma and the other makes a weaker imitation of it. That framing is wrong, and it leads to purchasing decisions made on marketing rather than on what is physically happening inside the tube.
"It's not that one is better than the other," Tatiana Sarmiento teaches. "One is just the concentration. How long it will take to process the blood." That is the whole answer, compressed. The rest of this piece unpacks why it is correct, what each protocol actually delivers, and how to decide which one belongs in your treatment room.
What a centrifuge is actually doing
Centrifugation is density-based separation. Spin anticoagulated whole blood and its components stratify by specific gravity: erythrocytes at the bottom, a thin intermediate buffy coat containing leukocytes and the densest platelet population, and plasma above. Platelets are the lightest cellular element, so they distribute through the plasma layer with a gradient — denser near the buffy coat interface, sparser at the top.
Everything that distinguishes PRP protocols follows from how you handle that gradient.
A spin does two things at once, and they oppose each other. Higher relative centrifugal force and longer duration drive more complete separation, pushing more platelets downward toward the interface where you can collect them. The same force also risks premature platelet activation and packs platelets into a pellet that does not fully resuspend. Every published protocol is a compromise between recovery and platelet integrity, which is why the parameters in the literature vary so widely and why device manufacturers guard their specific g-force and time settings.
The single spin: one separation, collected wide
In a single-spin ("soft spin") protocol, whole blood is spun once at relatively low force. Red cells sediment; the supernatant plasma, carrying most of the platelets in suspension, is drawn off. A published AGA trial used 3,000 rpm for 15 minutes as its single-spin arm (Legiawati et al., J Clin Aesthet Dermatol, 2023;16(12):39–44).
What you get is a larger volume of moderately concentrated plasma. Reported platelet concentration factors for single-spin, point-of-care systems commonly land in the two- to three-fold range over baseline whole blood, though well-engineered single-spin devices can do considerably better — one recent clinical device evaluation reported an eight-fold increase with an 83% platelet capture rate (Sussman et al., Bioengineering, 2026;13(7):780).
The important structural point is that a single spin gives you limited control over what else comes along. Where you place the pipette relative to the buffy coat determines your leukocyte and erythrocyte content, and that is a manual judgement made under time pressure. This is the parameter that matters most for skin and scalp work, and it is treated in full in the companion spoke on leukocyte-rich versus leukocyte-poor preparations.
The double spin: the second spin is not a second separation
The most common misunderstanding about double-spin protocols is that the second spin separates the blood again. It does not. The first spin has already removed the red cells. The second, harder spin acts on plasma alone, and its job is to pellet the platelets so that supernatant platelet-poor plasma can be discarded.
The same Legiawati protocol ran its double-spin arm at 1,500 rpm for 6 minutes followed by 2,500 rpm for 15 minutes. After the second spin, most of the plasma volume is removed and the platelet pellet is resuspended in the small volume that remains.
So the second spin is a volume-reduction step. You end with less liquid holding a higher density of platelets, and therefore a higher concentration of the alpha-granule growth factors that platelets carry — PDGF, TGF-β, VEGF, EGF and the rest of the cargo Tatiana describes as regulating "tissue response, angiogenesis and cellular communication."
This is exactly what she is describing when she says the double spin gives "more concentration of the growth factor than the single spin," and that with a single spin "you just need to use more volume in order to get the growth factor that you want to give to the patient."
The trade is concentration against volume, and dose is the product of both
Here is the arithmetic that resolves the debate.
What a follicle or a dermal plane receives is not a concentration. It is a dose — the absolute number of platelets delivered into the tissue, which is concentration multiplied by injected volume. A 3 mL preparation at 5× baseline and a 6 mL preparation at 2.5× baseline carry the same platelet payload.
That is why the classification systems that clinicians should be using report dose, not just concentration. The DEPA classification explicitly scores Dose of injected platelets, Efficiency of production, Purity of the preparation and Activation — precisely because earlier schemes reported concentration alone and made preparations look more different than they were (Magalon et al., BMJ Open Sport Exerc Med, 2016;2(1):e000060).
So the practical question is not "which spin is stronger." It is: can I deliver the platelet dose I want into the tissue volume the indication allows?
Two cases where that constraint bites:
- A small, defined treatment field. A discrete alopecic patch, a perioral field, the infraorbital skin. There is a ceiling on how much fluid you can place without creating unacceptable oedema or wheal distortion. If your volume ceiling is low, concentration is the only lever you have left, and the second spin earns its place.
- A large field. A full scalp, a whole face, the neck. Here volume is not the binding constraint, and a single spin that produces 6–8 mL of adequately concentrated plasma covers the field with platelet dose to spare.
What happens when you actually compare them in patients
This is where the evidence becomes useful and slightly uncomfortable.
A 2025 systematic review and meta-analysis pooled the randomised controlled trials comparing single-spin with double-spin PRP specifically in androgenetic alopecia — three RCTs, 90 participants. The results across every endpoint were null:
- Final platelet concentration: mean difference 66.14 favouring single spin (95% CI −372.96 to 505.25; p = 0.77; I² = 83.5%)
- Change in hair density: 4.10% (95% CI −4.74 to 12.93; p = 0.36)
- Terminal hair: 1.16 (95% CI −3.34 to 5.66; p = 0.61)
- Vellus hair: −3.59 (95% CI −12.49 to 5.30; p = 0.45)
(Ghanem et al., Frontiers in Medicine, 2025;12:1631087.)
Every confidence interval crosses zero. The honest reading is that in the published head-to-head trials, neither protocol has been shown to outperform the other on platelet yield or on clinical hair outcomes. The review's own stated conclusion — that single spin is superior — is not supported by its own confidence intervals, and the 83.5% heterogeneity on the platelet endpoint tells you the underlying protocols were not comparable enough to pool confidently in the first place. Read the intervals, not the abstract's last sentence.
That null result is not a failure of the question. It is the answer. If protocol choice were the dominant variable in PRP outcomes, three RCTs would have found a signal. The dominant variables sit elsewhere — in diagnosis, in dose delivered, in cell content, in treatment cadence, and in the pre-analytic handling covered in the spoke on why PRP protocols fail.
Processing time is a real clinical variable, not an afterthought
Tatiana raises processing time in the same breath as concentration, and clinicians routinely discount it. They should not.
Chair time. A single spin at 15 minutes versus a two-stage protocol at 6 plus 15 minutes, with a transfer and a resuspension step between them, is a difference of roughly 20 minutes per patient once handling is included. Across a hair-restoration day that is one or two additional treatment slots, and it determines whether PRP is a procedure you run in volume or a procedure you run occasionally.
Time from draw to injection. Every additional minute the sample spends in a tube is a minute of ongoing platelet activation, with progressive alpha-granule release into the plasma rather than into the patient. Longer protocols mean longer exposure. There is no consensus ceiling published for this interval, but the direction of the effect is not in dispute, and the operational rule follows: standardise the interval and keep it short, rather than letting it drift with how busy the room is.
Handling steps are error steps. The transfer between spins is a manual pipetting decision made by whoever is holding the syringe. More steps mean more opportunity for between-patient and between-operator variance — which, as the pre-analytic spoke details, is already wider than most clinicians assume even within a single patient.
Staffing. A two-stage protocol with a transfer step is harder to delegate safely than a closed single-spin device. If your workflow depends on a medical assistant processing while you are with another patient, protocol complexity is a staffing decision.
How to choose, in practice
Work through this in order.
- Fix the indication first. Scalp, facial skin quality, a small defined patch, or musculoskeletal work. This sets your volume ceiling and, more importantly, your leukocyte target.
- Set the cell content you want. For skin and scalp, a leukocyte-poor preparation. This constrains collection technique more than it constrains spin count.
- Work out the volume the field needs. Then ask whether your system can deliver an adequate platelet dose in that volume.
- Only now choose the spin protocol. If volume is constrained and you need concentration, double spin. If the field is large and throughput matters, a validated single-spin system is defensible and the comparative evidence does not contradict you.
- Standardise and stop changing it. The single greatest source of inconsistency in PRP practice is clinicians switching devices, kits and settings between patients and then trying to interpret outcomes across them. Whichever protocol you choose, run it the same way every time, with the same tube, the same anticoagulant, the same interval and the same operator technique.
What to document
Because there is no universal PRP, your chart note has to describe your product, not just name it. Record: volume of whole blood drawn, anticoagulant used, spin protocol (force and duration for each stage), final PRP volume, whether activation was used, and the volume injected per region. If you run periodic cell counts on your preparation, record those too.
That record is what lets you compare a responder to a non-responder six months later. Without it, every outcome you observe is uninterpretable — which is a far more expensive problem than choosing the "wrong" number of spins.
These figures and techniques reflect Tatiana Sarmiento's clinical practice as taught in Empire Medical Training's hands-on curriculum. Technique is learned under supervision; this article is educational and is not a substitute for training.
Preparation is one variable in a protocol that also includes diagnosis, cell content, injection pattern and maintenance. Empire's Platelet Rich Plasma Training and Medical Hair Loss Treatment, PDO Threads and PRP Hair Restoration Training cover preparation and delivery together, under supervision, which is the only way the handling variables above become reliable.
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This article reflects the clinical opinions and experience of Tatiana Sarmiento, Empire Medical Training faculty, an independent faculty member contributing to Empire Medical Training's curriculum. The views expressed are the author's own and do not necessarily represent those of Empire Medical Training.
It is professional education, not medical advice, and is no substitute for hands-on training or independent clinical judgment. Licensed clinicians remain responsible for their own patient selection, technique and outcomes, for verifying current product labelling, and for practising within their scope and applicable law. Empire Medical Training accepts no liability for reliance on this content.