What is the optimal platelet‑rich plasma (PRP) protocol—including preparation method, platelet concentration, activation, injection technique, and treatment schedule—for adult patients (approximately 25‑55 years) with androgenetic alopecia undergoing hair transplantation?

Optimal PRP Protocol for Hair Transplantation

For adult patients undergoing hair transplantation for androgenetic alopecia, use a manual double-spin centrifugation method to prepare PRP with 1.0–1.5 million platelets/µL, deliver 5–7 mL per session without activation, and administer three sessions at transplant (month 0), month 1, and month 3, followed by maintenance injections every 6 months indefinitely. 1, 2

Preparation Method

Use the manual double-spin centrifugation technique exclusively for preparing PRP in hair transplant patients. 1, 3 This method consistently produces superior platelet concentrations compared to single-spin protocols. 4, 5

Technical Specifications:

• First spin: 1,500 rpm for 6 minutes 5
• Second spin: 2,500 rpm for 15 minutes 5
• Anticoagulant: Citrate-anticoagulated whole blood (avoid EDTA) 1
• Target concentration: 1.0–1.5 million platelets per microliter 1

The double-spin method yields 4–5 times baseline platelet counts and produces significantly higher terminal hair density improvements compared to single-spin preparations. 4, 5

Platelet Concentration

Target 1.0–1.5 million platelets/µL as the therapeutic range. 1, 6 Higher platelet concentrations within this range correlate directly with greater hair density, follicle diameter, and terminal hair improvements. 6 Concentrations below this threshold lead to treatment failure. 3, 6

Activation Status

Do NOT activate PRP before injection. 1, 2 This is a critical technical point: nonactivated PRP demonstrates 31% greater increases in hair count and density compared to activated preparations. 2, 3 The collagen-rich scalp tissue provides sufficient endogenous activation. 1 Adding calcium gluconate or other activators before injection provides no clinical benefit and reduces efficacy. 4

Injection Technique for Hair Transplant Patients

Timing and Coverage:

• First injection: At time of hair transplantation (month 0) 2
• Coverage area: Inject across the entire recipient zone where follicular units were transplanted, not isolated spots 2
• Pre-treatment option: Consider PRF pre-treatment 7 days before surgery with follicles soaked in PRF during the procedure for enhanced early regrowth 1

Technical Execution:

• Needle: 30-gauge × 4 mm 1, 2, 3
• Angle: 90 degrees perpendicular to scalp surface 1, 2
• Depth: 2–4 mm (full bevel of needle) to reach dermal papilla cells 1, 2
• Spacing: Injections 1 cm apart in systematic grid pattern 1, 2
• Volume per session: 5–7 mL total PRP 1, 2
• Dosing: 0.05–0.1 mL/cm² of scalp surface 1, 2

Pre-Injection Preparation:

• Map and clearly mark all transplanted areas before injection 1, 2
• Patient must shampoo and detangle hair, avoiding all styling products 1, 3
• Apply pharmaceutical-grade topical anesthetic cream due to significant injection pain 1, 3
• Position patient for 360-degree scalp access 1

Treatment Schedule

Initial Phase (Post-Transplant):

• Session 1: At time of transplant (month 0) 2
• Session 2: One month after transplant 2
• Session 3: Three months after transplant 2

Maintenance Phase:

Administer maintenance injections every 6 months indefinitely after completing the initial three sessions. 1, 2, 3, 6 This maintenance schedule is essential—discontinuation leads to reversal of benefits. 3

Alternative Timing for Non-Transplant AGA:

For patients receiving PRP without transplant surgery, use 1 session every 4–6 weeks for 3 sessions total per year, then evaluate after one year before transitioning to 6-month maintenance. 1

Combination Therapy for Optimal Outcomes

Always combine PRP with topical minoxidil 5% for superior results. 2, 3, 6 The combination produces 57% median increase in terminal hair density versus 48% with minoxidil alone at 32 weeks. 3

Concurrent Medications:

• Minoxidil 5%: Apply 1 mL twice daily throughout treatment and continue indefinitely 2, 3
• Finasteride: Consider starting 1 month before transplant as background therapy 2, 6
• Triple combination (PRP + minoxidil + finasteride) represents the most effective evidence-based approach 2

Expected Timeline and Outcomes

• Initial improvements: Visible 2–3 months after treatment 2
• Peak response: Maximum effect typically achieved by 6 months 3
• Hair density increase: 1.74 times baseline 2
• Hair diameter increase: 14.3 times baseline 2
• Early predictor: 25% improvement in hair density at 2 months predicts sustained response at 6 months 3, 6

Critical Pitfalls to Avoid

Technical Errors:

• Incomplete coverage: Do not skip sub-areas within the recipient zone; incomplete coverage reduces efficacy 2
• Superficial injection: Maintaining 2–4 mm depth is essential for targeting dermal papilla cells 2
• Using activated PRP: Activation reduces efficacy by 31% 2, 3
• Single-spin preparation: Produces inferior platelet concentrations and clinical outcomes 4, 5

Protocol Errors:

• Low platelet concentration: Below 1.0 million/µL leads to treatment failure 3, 6
• Inadequate injection volume: Less than 5 mL per session reduces efficacy 6
• Insufficient treatment frequency: Skipping maintenance sessions causes benefit reversal 2, 3
• Omitting combination therapy: PRP monotherapy is significantly less effective than combination with minoxidil 2, 3, 6

Monitoring Failures:

• Evaluate treatment response using standardized photographs, trichoscopy for hair density and diameter, and patient self-assessment 3, 6
• Key positive indicators include increased hair density per cm², increased shaft diameter, decreased telogen proportion, and improved patient satisfaction 3, 6

Emerging Alternative: Platelet-Rich Fibrin (PRF)

PRF shows theoretical advantages over PRP including lower cost, easier preparation, and sustained growth factor release. 3 For hair transplant applications, PRF can be used with pre-treatment 7 days prior to surgery and for soaking follicles during the procedure, demonstrating substantial early hair regrowth by month 6. 1 However, the evidence base for PRF remains limited compared to PRP, and standardized protocols are still needed. 6