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Technical article · PRP standardization & reporting
Characterizing PRP correctly: platelet dose, recovery and cell profile
Two preparations can both be labeled as platelet-rich plasma (PRP) and yet differ significantly. Concentration, volume, absolute platelet count, recovery, leukocyte and erythrocyte percentage, and activation status each describe different properties. This article shows which parameters are relevant for a comprehensible characterization of PRP – and where their informative value ends.
Three preparations – one name
PRPlower WBC content
PRPhigher WBC content
PRPadditional RBC fraction
PlateletsLeukocytesErythrocytes
12.1%The musculoskeletal PRP studies examined described the production process as comprehensively reproducible.[1]
26.6%They reported the composition of the final PRP quantitatively.[1]
6Historical classification systems are compared in this article.
The most important points in brief
- Three key figures, three questions: Concentration factor, absolute platelet count and recovery describe different properties – none replaces the other.
- No volume, no dose: Only concentration multiplied by volume yields a total number. The volume obtained and the volume actually used must be separated.
- PRP is more than just platelets: Leukocytes, neutrophils, erythrocytes, activation and manufacturing parameters are part of the characterization.
- No ranking: Six classifications each represent specific aspects. MIBO supplements the requirements for study reporting.
1The fundamental problem
What does "PRP quality" actually mean?
The term "PRP quality" is used very differently. Sometimes it refers to a high platelet concentration, sometimes to a low leukocyte count, high recovery, or a particularly platelet-rich cell profile. Such an equation is problematic.
In this article, we refer to PRP quality primarily depends on the comprehensible characterization and documentation of a preparation.The more completely it is known what was obtained from which starting material using which method and subsequently used, the better it is possible to compare preparations and scientific papers.
A recent comprehensive review identifies precisely this variability as one of the central standardization problems: platelet and leukocyte counts, erythrocyte contamination, activation, recovery, as well as manufacturing and isolation methods differ considerably in some cases.[2]
Therefore, the following applies to this article:
A high concentration, recovery, or a specific classification level is no cross-indication efficacy or quality rankingThe key figures initially describe the product.
2Key figure 1
Concentration factor: Why “4× PRP” alone says little
The concentration factor describes the ratio between the platelet concentration in the extracted PRP and the initial concentration in whole blood. Our consistent calculation example uses 250,000 platelets/µl in whole blood and 1,000,000/µl in the extracted PRP.
Concentration factor=
Platelet concentration in PRPPlatelet concentration in whole blood
Master example: 1,000,000/µl ÷ 250,000/µl = 4×
What's missing from this number is the volume. That's precisely why a concentration factor alone doesn't tell you anything about how many platelets are actually contained in the extracted or used PRP.
Fig. 1 · Same concentration ≠ same total number
Preparation A
1,000,000/µl
× 1 ml
Preparation B
1,000,000/µl
× 3 ml
3Key figure 2
Absolute platelet dose: Concentration × Volume
If the volume is taken into account in addition to the concentration, the absolute platelet count can be determined.
Absolute platelet count=platelet concentration×considered volume
Master example: 1,000,000/µl × 3 ml (= 3,000 µl) = 3 billion Platelets
With 1,000,000 platelets/µl and 3 ml of PRP obtained, there are theoretically... 3 billion platelets in the total volume gained.
The linguistic distinction is important: The Total number won is not necessarily identical to the Total number actually used or appliedIf only a portion of the extracted PRP is used, the two values will differ.
What current studies on concentration and total number show
Total number · Knee osteoarthritis
1–5, 5–10 and >10 billion
Grouping of the meta-analysis; 5–10 billion showed the greatest functional effect estimate compared to hyaluronic acid in this knee osteoarthritis analysis – no general target specification.
A meta-analysis published in 2026 grouped PRP according to the total deliverable platelet doseIn this knee osteoarthritis analysis, the range of 5–10 billion was associated with the strongest functional effects compared to hyaluronic acid.[3]
No general target: The data are indication- and protocol-specific and do not define a universal PRP dose.
Concentration factor · Knee osteoarthritis
Moderate enrichment instead of "more is always better"
Concentration factor compared to whole blood; moderate ranges were more favorably associated in this knee osteoarthritis analysis – no general target range.
A meta-analysis published in 2025 ranked studies according to the concentration factor relative to whole blood. In this knee osteoarthritis analysis, moderate concentration ranges were associated with more favorable outcomes than very high concentrations.[4]
This also does not imply a general sweet spot. Concentration factor and total number are different quantities.
Why these findings do not necessarily contradict each other
A moderate concentration factor can yield a high absolute platelet count in a larger final volume. Conversely, a highly concentrated preparation in a very small volume can contain a lower total platelet count. Therefore, concentration factor and dose should not be equated.
Concentration factor
Preparation X8×
Preparation Y4×
Total total number
Preparation X2 billion
Preparation Y3 billion
Example calculation with a baseline of 250,000/µl: X = 2,000,000/µl × 1 ml · Y = 1,000,000/µl × 3 ml. Fictitious values, not a treatment recommendation.
4Key figure 3
Platelet Recovery: how many platelets are recovered?
Platelet recovery describes the proportion of platelets present in the processed starting blood that are recovered in the obtained PRP after processing.
Recovery (%)=
PRP concentration × PRP volume obtainedWhole blood concentration × processed blood volume×100
Master example: 3 billion ÷ 5 billion × 100 = 60%
In our master example, 20 ml of whole blood with 250,000 platelets/µl theoretically contains 5 billion platelets. The extracted PRP contains 3 billion. This results in a recovery of 60%.
The DEPA classification uses this size as a measure of Production efficiency.[5] A higher recovery rate initially means that a larger proportion of the original platelets were recovered in the extracted PRP. It is not a direct indicator of efficacy.
Concentration factor
How much has the concentration increased compared to baseline?
In the master example: 4×Recovery
What proportion of the original platelets were recovered?
In the master example: 60%Dose / Total number
How many platelets are in the volume under consideration?
In the master example: 3 billion wonInteractive
Understand PRP metrics using a numerical example.
The default values correspond to the master example. Changes are for mathematical illustration purposes only.
ml processed
×10³/µl
ml
×10³/µl
ml · max. volume obtained
4.0×Concentration factor
3.00 billionin the PRP gained
60.0%Platelet Recovery
2.00 billionin the volume used
Where do the platelets go?
In processed whole blood5.00 billion
In the won PRP3.00 billion
In the volume used2.00 billion
This is a calculation aid to explain key figures; it does not constitute a therapy, product, or dosage recommendation. Actual values must be measured; they must not be estimated based solely on tube or system properties.
5Key figure 4
Purity and cell profile: PRP consists of more than just platelets.
Depending on the preparation method, PRP preparations can contain varying proportions of platelets, leukocytes, and erythrocytes. Neutrophils are also considered separately in some classification systems.
In addition to dose and recovery, the DEPA classification also included the Purity One. This involves considering the relative proportion of platelets among the cellular components of the preparation. The original study distinguishes between >90%, 70–90%, 30–70%, and <30%.[5]
A>90%very pure
B70–90%pure
C30–70%heterogeneous
D<30%whole blood PRP
DEPA purity: relative platelet content of the cells considered – levels of description, not a ranking.
Pay attention to the nomenclature
Terms like "pure" and "very pure" are designations within the DEPA classification. They do not automatically mean "clinically better" or "more effective." The original paper itself warns against interpreting classification letters as a ranking of quality.[5]
High or low in leukocytes: Is one fundamentally better than the other?
The biological significance of leukocytes is complex. Furthermore, "leukocytes" is a collective term for various cell populations with different functions. Therefore, the leukocyte count cannot be meaningfully assessed using a simple rule of "present = bad" or "absent = good".
A network meta-analysis published in 2026 compared leukocyte-rich PRP, leukocyte-poor PRP, hyaluronic acid, and placebo in the treatment of knee osteoarthritis. Twenty-one randomized controlled trials with a total of 2,254 patients were included. The analysis did not show a statistically significant direct difference in efficacy between LP-PRP and L-PRP.[6]
21randomized trials included
2,254Patients with knee osteoarthritis
LP vs. Lno significant direct difference in effectiveness
This does not mean that the leukocyte count is irrelevant. Cell composition is a relevant preparation property; its clinical significance must be investigated in a manner specific to the indication and protocol.
The PAW classification already takes into account neutrophils in addition to total leukocytes.[7] In more detail: PRP beyond platelet count: Proteomics and metabolomics.
6Process parameters
Activation as a standalone parameter
Activation status
Activation status is also a recurring parameter in PRP classifications. It is relevant for a comprehensible characterization. whether and in what way exogenous activation was performedCalcium compounds or thrombin, for example, are described in the literature. Activation status is a component of Mishra, PAW, PLRA, DEPA, and MARSPILL.[9]–[11] However, "activated" or "not activated" does not imply any general ranking.
Single Spin and Double Spin: Manufacturing feature instead of quality seal
An additional centrifugation step can influence final volume, cell concentrations, and cell distribution. However, this does not automatically mean that double-spin PRP is clinically superior to a single-spin preparation. MARSPILL includes the number of centrifugation steps as a manufacturing parameter.[11]
Technical basics: PRP centrifugation: RCF, RPM, rotor radius and runtime.
Fig. 2 · From whole blood to characterized PRP
1 · Exit
20 ml whole blood
250,000 platelets/µl
= 5 bn baseline2 · Processing
Proceedings
System · RCF · Time
Spins · Activation
3 · Won
3 ml PRP
1,000,000 platelets/µl
= 3 bn obtained4 · Derived Values
- 4×Concentration factor
- 60%Recovery
- 2 billionused at 2 ml
Additionally, document:
WBCNeutrophilsRBCActivationFinal volumeTube systemCentrifugationvolume used
Only the combination of initial values, process data and end-product measurement makes PRP comprehensibly comparable.
7nomenclature
Six PRP classifications – and why none of them describes everything.
The well-known PRP classifications emerged at different times and with different focuses. They should not be understood as competing grades. Each describes a specific aspect of the preparation or manufacturing process.
Celebration2009
- Focus
- Leukocytes + fibrin architecture
- Distinctive feature
- P-PRP, L-PRP, P-PRF, L-PRF
Dohan Ehrenfest et al. classified platelet concentrates based on leukocyte content and fibrin architecture into P-PRP, L-PRP, P-PRF and L-PRF.[8] The system does not provide a universal numerical WBC threshold from which "leukocytes present" could be automatically derived based solely on the cell count.
Captures:WBCFibrin architecture
Mishra2012
- Focus
- WBC, activation, concentration level
- Distinctive feature
- historical 5× limit
Mishra et al. combined leukocyte count, exogenous activation and a historical concentration limit of about 5× compared to baseline.[9] This 5× limit is a classification limit and not proof of a therapeutically optimal concentration.
Captures:PlateletsWBCActivation
PAW2012
- Focus
- Platelets, Activation, White cells
- Distinctive feature
- Neutrophils considered separately
PAW stands for Platelets, Activation, and White Cells. The system describes platelet concentration/count, activation status, and leukocyte profile; neutrophils are also taken into account.[7] An absolute applied dose calculated as concentration × volume is not an independent PAW parameter.
Captures:PlateletsWBCNeutrophilsActivation
PLRA2015
- Focus
- Platelets, Leukocytes, RBC, Activation
- Distinctive feature
- Volume relevant for quantitative interpretation
PLRA stands for Platelets, Leukocytes, Red blood cells, and Activation. Mautner et al. also called for the volume used to be reported in such a way that quantitative differences between preparations become comprehensible.[10] Some historical boundary definitions still require explanation in their practical operationalization.
Captures:Plateletsapplied volumeWBCRBCActivation
DEPA2016
- Focus
- Dose, Efficiency, Purity, Activation
- Distinctive feature
- Recovery and relative cell purity
DEPA stands for Dose, Efficiency, Purity, and Activation. This classification combines absolute platelet count, recovery, relative cell composition, and activation status.[5] The categories are descriptions – not a universal effectiveness ranking.
Captures:Plateletsabsolute doseWBCRBCActivationRecovery
MARSPILL2017
- Focus
- Cell profile + process parameters
- Distinctive feature
- including spins, image guidance and light activation
MARSPILL expands the classification to include process parameters such as manufacturing method, activation, RBC, number of spins, platelets, image guidance, leukocytes and light activation.[11] This allows the system to answer different questions than a purely cellular classification.
Captures:PlateletsWBCRBCActivationProcess/Application
Fig. 3 · What do the six classifications cover?
| system | platelets | absolute dose | WBC | Neutrophils | RBC | Activation | Recovery | Fibrin architecture | Process/Application |
|---|---|---|---|---|---|---|---|---|---|
| Celebration2009 | not recorded | not recorded | recorded | not recorded | not recorded | not recorded | not recorded | recorded | not recorded |
| Mishra2012 | recorded | not recorded | recorded | not recorded | not recorded | recorded | not recorded | not recorded | not recorded |
| PAW2012 | recorded | not recorded | recorded | recorded | not recorded | recorded | not recorded | not recorded | not recorded |
| PLRA2015 | recorded | ◐Derivable from concentration and applied volume, not an independent PLRA category | recorded | not recorded | recorded | recorded | not recorded | not recorded | not recorded |
| DEPA2016 | recorded | recorded | recorded | not recorded | recorded | recorded | recorded | not recorded | not recorded |
| MARSPILL2017 | recorded | not recorded | recorded | not recorded | recorded | recorded | not recorded | not recorded | recorded |
| recorded in | 5/6 | 2/6 | 6/6 | 1/6 | 3/6 | 5/6 | 1/6 | 1/6 | 1/6 |
◐ PLRA: An absolute total number can be derived from platelet concentration × applied volume, but there is no independent PLRA category.
8Operationalization
Where classifications reach their limits
Historical classification systems are helpful, but not fully operationalized for every modern software logic. Therefore, job vacancies should be clearly indicated.
Celebration
No universal WBC limit
The classification is based on leukocyte count and fibrin architecture. A generally defined numerical threshold from which software could automatically deduce "leukocytes present" is not specified.[8]
DEPA
Volume recovered vs. volume actually used
The original paper refers to "dose of injected platelets," but calculates it from concentration × total volume of PRP obtained. The actual amount used may differ.[5]
PLRA / MARSPILL
Don't invent borderline cases
Where historical definitions do not clearly operationalize reference points or exact limiting cases, a digital classification should make this uncertainty visible instead of adding its own rules.
Interpreting your own PRP measurements
If baseline and final values are available, concentration factor, dose, recovery and cell profile can be calculated separately and then classified according to published classification systems.
9Reporting
MIBO: reporting rather than classification
MIBO stands for Minimum Information for Studies Evaluating Biologics in OrthopaedicsThe recommendations published in 2017 were developed through a Delphi consensus process and resulted in a 23-point checklist for PRP.[12]
2017published
DelphiConsensus process
23Points in the PRP checklist
MIBO is therefore no seventh PRP classificationClassification systems describe the properties of a preparation; MIBO describes what information a study should report so that its methodology can be assessed and reproduced in a comprehensible manner.
The reporting problem persists.
A recent analysis of 87 knee osteoarthritis RCTs found particularly low reporting rates for baseline whole blood, recovery, end-product analysis and activation.[13]
When differently composed preparations are grouped under the same collective term "PRP", it makes the interpretation and comparability of clinical studies more difficult.
10System information
What manufacturer and system specifications cannot determine
A PRP system or PRP tubes It can be described in precise technical detail. Manufacturer specifications can document, for example, tube volume, material, anticoagulant, separation gel, intended centrifugation conditions, or a planned final volume.
However, such information does not replace an actual quantitative analysis of the starting blood and the extracted PRP. Without corresponding measurement data, the following cannot be automatically determined for the individual processing procedure:
- actual baseline and PRP platelet concentration
- Concentration factor and recovery
- absolute platelet count obtained or actually used
- actual leukocyte and erythrocyte count
- Full classification according to DEPA, PAW or PLRA
A blanket statement – not reliable in this form.
This tube always produces 5× PRP.
Such a general statement would only be reliable if the necessary measurement data and conditions were properly documented.
11Evidence
What can be deduced from the current state of research – and what cannot.
Well-founded
- PRP preparations can differ significantly in their composition.
- Concentration factor and absolute platelet count are different quantities.
- The volume under consideration influences the absolute total number.
- Recovery describes the efficiency of platelet collection.
- Cell profile, activation and manufacturing parameters should be documented.
- Incomplete reporting makes it difficult to compare studies.
Not generally derivable
- a universally optimal concentration factor
- a universally optimal platelet dose
- a fundamentally superior LR/LP composition
- a clinically “best” recovery
- a fundamentally superior DEPA category
- a generally superior single or double spin method
12Conclusion
PRP should be measured and described, not just named.
The term "PRP" alone reveals relatively little about the actual preparation. Even a description like "4x concentrated" doesn't answer how many platelets were harvested or used, what the recovery rate was, or what other cell components were included.
The complete characterization chain
- 1Baseline
- 2concentration
- 3volume
- 4absolute platelet count
- 5Recovery
- 6Cell profile
- 7Activation
- 8Manufacturing parameters
Classifications such as Ehrenfest, Mishra, PAW, PLRA, DEPA, and MARSPILL represent different parts of this information. MIBO supplements these classifications with requirements for transparent scientific reporting.
None of these classifications is a general ranking of "good" and "bad" PRP. Their value lies in replacing the vague umbrella term PRP with measurable and documentable properties.
Don't just name PRP, document it in a comprehensible way.
The PRP classification and reporting calculator separates concentration factor, DEPA dose, actual dose used, recovery, and cell profile, and classifies existing data according to six published systems. Missing or ambiguous values are not estimated.
FAQAnswered briefly
Frequently asked questions about PRP characterization
A value of 5× generally means that the platelet concentration in the PRP is five times higher than in the baseline blood sample. It describes a concentration factor. Without volume, the absolute platelet count cannot be determined from this.
This cannot be stated generally. Current studies are investigating both concentration factors and absolute platelet counts. For knee osteoarthritis, the data do not show a simple linear rule of "more is better." Results from this indication cannot be readily transferred to other applications.
The absolute platelet count is calculated by multiplying the platelet concentration by the volume of PRP being considered. It is important to distinguish whether this refers to the total volume of PRP obtained or only the volume actually used.
Platelet recovery describes the proportion of platelets present in the processed whole blood that are recovered in the obtained PRP. It is therefore a measure of processing efficiency and not a direct indicator of clinical efficacy.
LR-PRP and LP-PRP differ in their leukocyte profile. The precise classification depends on the definition or classification used. Current evidence does not support a universally applicable superiority of one form over the other.
DEPA stands for Dose, Efficiency, Purity, and Activation. The system describes absolute platelet count, platelet recovery, relative cellular composition, and activation status. These categories are classification levels and not a general efficacy ranking.
None of the established classifications fully encompass all PRP parameters. Ehrenfest, Mishra, PAW, PLRA, DEPA, and MARSPILL each have different focuses. Therefore, for scientific reporting, the underlying measurements and manufacturing parameters should also be specified directly.
The number of centrifugation steps alone does not indicate a general clinical superiority. Both methods can produce different final volumes and cell profiles. The crucial factor is to characterize the actual resulting preparation and to document the protocol used in a traceable manner.
↗Read more
Further information can be found at PRPmed
Biological basis of PRPPlatelets, plasma and basic properties of PRP.
Impact, evidence and limitationsClinical classification of different research fields.
PRP injection techniquesApplication procedures and documentation parameters.
Proteomics & MetabolomicsMolecular differences beyond classical cell counts.
PRP centrifugationCorrectly classify RCF, RPM, rotor radius and runtime.
PRP classification & reportingCalculate key performance indicators and classify them according to six systems.
References
- Lim HC et al. Most Orthopaedic Platelet-Rich Plasma Investigations Don't Report Protocols and Composition: An Updated Systematic Review. Arthroscopy. PMID 38522650. PubMed
- Rath M et al. Platelet-rich plasma – A comprehensive review of isolation, activation, and application. Acta Biomaterialia. 2025;204:52–75. PMID 40712724. PubMed
- Hooper N et al. Platelet-rich plasma outcomes in knee osteoarthritis are associated with the amount of total deliverable platelets: A systematic review and meta-analysis. PM&R. 2026;18(2):210–222. PMID 40980837. PubMed
- Simental-Mendía M et al. Influence of platelet count on the clinical effectiveness of platelet-rich plasma in the treatment of knee osteoarthritis: A systematic review and meta-analysis. Orthop Traumatol Surg Res. 2025. PMID 41067625. PubMed
- Magalon J et al. DEPA classification: a proposal for standardising PRP use and a retrospective application of available devices. BMJ Open Sport Exerc Med. 2016;2:e000060. PMID 27900152. PMC
- Xu B et al. Leukocyte-rich versus leukocyte-poor platelet-rich plasma and hyaluronic acid for knee osteoarthritis: a systematic review and network meta-analysis. J Orthop Surg Res. 2026. PMID 41629990. PubMed
- DeLong JM, Russell RP, Mazzocca AD. Platelet-rich plasma: the PAW classification system. Arthroscopy. 2012;28(7):998–1009. PMID 22738751. PubMed
- Dohan Ehrenfest DM, Rasmusson L, Albrektsson T. Classification of platelet concentrates: from pure platelet-rich plasma (P-PRP) to leucocyte- and platelet-rich fibrin (L-PRF). Trends Biotechnol. 2009;27(3):158–167. PMID 19187989. PubMed
- Mishra A, Harmon K, Woodall J, Vieira A. Sports medicine applications of platelet rich plasma. Curr Pharm Biotechnol. 2012;13(7):1185–1195. PMID 21740373. PubMed
- Mautner K et al. A Call for a Standard Classification System for Future Biologic Research: The Rationale for New PRP Nomenclature. PM&R. 2015;7(4 Suppl):S53–S59. PMID 25864661. PubMed
- Lana JFSD et al. Contributions for classification of platelet rich plasma – proposal of a new classification: MARSPILL. Regen Med. 2017;12(5):565–574. PMID 28758836. PubMed
- Murray IR et al. Minimum Information for Studies Evaluating Biologics in Orthopaedics (MIBO): Platelet-Rich Plasma and Mesenchymal Stem Cells. J Bone Joint Surg Am. 2017;99(10):809–819. PMID 28509821. PubMed
- Nakagawa HF et al. Systematic Review of Randomized Controlled Trials Evaluating the Use of Platelet-Rich Plasma for Knee Osteoarthritis: Adherence to Minimum Information for Studies Evaluating Biologics in Orthopaedics. Am J Sports Med. 2025;53(5):1241–1253. PMID 39754417. PubMed
Note for professional users: This article provides a scientific and technical overview of PRP characterization parameters. It does not constitute a diagnosis, therapy, dosage, or treatment recommendation. Manufacturer specifications, intended use, and instructions for use of the medical devices employed, as well as professional assessment within the specific medical context, remain paramount.