PRP Hair Treatment: The Science Behind Hair Restoration and Skin Rejuvenation
In recent years, PRP hair treatment has emerged as a groundbreaking approach to combat hair loss and promote regrowth. This innovative therapy harnesses the power of platelet-rich plasma, a concentrated source of growth factors derived from the patient's own blood, to stimulate hair follicles and enhance hair density. As more individuals seek natural and effective solutions for hair restoration, PRP injections for hair loss have gained significant attention in the medical community and among those struggling with thinning hair or androgenetic alopecia.
The science behind PRP hair treatment is rooted in the body's natural healing processes. By using a patient's own platelets, this therapy aims to jump-start hair growth and improve overall hair health. Throughout this article, we'll explore the biological mechanisms that make PRP an effective hair growth therapy, discuss its success rate, and compare it to traditional hair loss treatments. We'll also delve into the PRP treatment process, its potential benefits, and what patients can expect in terms of results and cost. By understanding the science and application of PRP for hair loss, readers will gain valuable insights into this promising approach to hair restoration.
The Biology of Hair Growth and Loss
Understanding the intricate biology of hair growth and loss is crucial for comprehending the mechanisms behind hair restoration treatments such as PRP hair treatment. This section delves into the hair growth cycle, causes of hair loss, and factors affecting hair health.
Hair Growth Cycle
The hair growth cycle consists of four primary phases: anagen, catagen, telogen, and exogen. The anagen phase, or growth phase, is characterized by active hair production and can last from two to eight years [1]. During this phase, hair follicles are highly mitotic, producing new hair shafts. Approximately 80% to 90% of the hair is in the anagen phase at any given time .
The catagen phase, also known as the regression phase, follows anagen and lasts about two weeks. During this brief transitional period, the hair follicle regresses and moves upward towards the hair-follicle bulge . If the dermal papilla fails to reach the bulge during catagen, follicle cycling terminates, resulting in hair loss .
The telogen phase, or resting phase, typically lasts two to three months. About 9% of total scalp hair resides in this phase . During telogen, new hair begins to develop at the base of the follicle, eventually pushing out the old hair .
The final phase, exogen, marks the shedding of old hair and the initiation of a new anagen phase. Normal shedding occurs at a rate of 100 to 150 telogen hairs per day .
Causes of Hair Loss
Hair loss can result from various factors, with differences observed between men and women. In men, genetic factors often contribute to male-pattern baldness, while in women, hormonal changes during pregnancy, menopause, or conditions like polycystic ovary syndrome (PCOS) can cause hair loss [4].
Androgenetic alopecia (AGA) is a common form of hair loss characterized by progressive miniaturization of hair follicles. It affects approximately 50% of Caucasian men by age 50 and up to 50% of women over their lifetime [5]. In men, baldness typically starts with frontal recession and thinning of hair on the vertex area, while in women, hair loss is characterized by reduced hair density and smaller hair shaft diameter over the crown without frontal hairline recession [5].
Other causes of hair loss include medical conditions such as thyroid disorders, anemia, autoimmune diseases, and certain medications or treatments [4]. Telogen effluvium, a type of diffuse hair loss, can occur 1 to 6 months after a stressor causes a larger portion of hair to shift from the anagen phase to the telogen phase [6].
Factors Affecting Hair Health
Several factors can influence hair health and the balance between anagen and telogen phases:
Inflammation: Chronic inflammation can promote anagen to telogen transition and has been associated with various types of alopecia, including stress-induced hair loss, alopecia areata, and androgenetic alopecia [7].
Hormones: Thyroid hormones, dihydrotestosterone (DHT), estrogen, and testosterone play crucial roles in hair growth. For instance, hypo- and hyperthyroidism can cause reversible, diffuse hair loss by promoting premature transition from anagen to telogen [8].
Stress: Psychological stress can foster anagen to telogen transition and is closely related to telogen effluvium [9].
Nutrition: Proper nutrition is essential for maintaining the anagen and telogen balance. Caloric or nutritional deficiencies can negatively impact hair structure, growth, and pigmentation. Studies have found associations between nutritional deficiency and various types of hair loss, including chronic telogen effluvium, androgenetic alopecia, and alopecia areata .
Blood Flow: Increased blood flow to the scalp can promote telogen to anagen transition and subsequent hair growth .
Understanding these biological factors is essential for developing effective hair restoration treatments, including PRP hair treatment, which aims to stimulate hair growth by targeting various aspects of the hair growth cycle and addressing underlying causes of hair loss.
Platelet-Rich Plasma: A Natural Approach to Hair Restoration
Platelet-rich plasma (PRP) has emerged as a promising treatment for various conditions, including hair loss. This innovative therapy harnesses the body's natural healing processes to stimulate hair growth and improve overall hair health. PRP injections have gained significant attention in the medical community, particularly in the field of trichology, for their potential to address androgenetic alopecia and other forms of hair loss.
Definition and Composition of PRP
Platelet-rich plasma is defined as a small volume of plasma containing a higher concentration of platelets than that found in peripheral blood [1]. It is derived from whole blood and consists of two main components: plasma, the liquid portion of blood, and platelets, blood cells that play a crucial role in healing throughout the body . The concentration of platelets in PRP is typically two to six times higher than the normal platelet count, which is essential for optimal therapeutic outcomes .
Platelets contain alpha-granules, which store and release numerous growth factors and cytokines when activated. These bioactive proteins, including platelet-derived growth factor (PDGF), transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF), are responsible for stimulating cell proliferation, differentiation, and angiogenesis .
Extraction and Preparation Methods
The preparation of PRP involves a standardized process, although there may be variations in specific protocols. The general steps include:
Blood collection: A peripheral blood sample, typically 10 to 60 mL, is drawn from the patient [4].
Anticoagulation: The blood is mixed with an anticoagulant, such as acid citrate dextrose or sodium citrate, to prevent premature clotting and alpha-granule secretion [4].
Centrifugation: The anticoagulated blood is centrifuged to separate its components based on specific gravity [4].
Separation: After centrifugation, the blood is divided into three layers: red blood cells at the bottom, PRP in the middle, and platelet-poor plasma (PPP) at the top [4].
Some clinics use commercial PRP kits to simplify the preparation process. These kits may result in varying platelet concentrations, leukocyte content, and the presence of platelet activators [7].
Activation of Platelets
Activation is a crucial step in the PRP protocol, as it initiates the platelet degranulation process and the release of growth factors. There are several methods of activation:
Calcium chloride (CaCl2): This method results in a gradual release of growth factors over time, with levels increasing progressively up to 24 hours after activation [10].
Autologous thrombin: Thrombin activation leads to a rapid release of growth factors, with the highest levels observed within the first hour [10].
Combination of CaCl2 and thrombin: This method creates platelet-rich fibrin, resulting in a soft gel that can be applied to increase post-operative wound healing [11].
Collagen type I: This method mimics in situ activation but may result in lower growth factor release compared to other activators .
Some practitioners prefer to rely on endogenous collagen present in the connective tissues to activate platelets naturally upon injection . However, studies have shown that this method may result in significantly lower growth factor release compared to exogenous activation methods [13].
The choice of activation method can influence the formation of the platelet clot and the kinetics of growth factor release. This, in turn, may affect the therapeutic efficacy of the PRP treatment for hair restoration. The optimal activation strategy may depend on the specific condition being treated and the desired release profile of growth factors.
Mechanism of Action: How PRP Stimulates Hair Growth
Growth Factors and Cytokines
Platelet-rich plasma (PRP) contains a high concentration of platelets, which are rich in growth factors and cytokines. These chemical messengers play a crucial role in cellular communication and tissue regeneration [1]. When activated, platelets release over 300 biologically active molecules from their α-granules and dense granules . Among these, several growth factors are particularly important for hair growth stimulation:
Platelet-derived growth factor (PDGF)
Vascular endothelial growth factor (VEGF)
Epidermal growth factor (EGF)
Fibroblast growth factor (FGF)
Insulin-like growth factor-1 (IGF-1)
Transforming growth factor-β (TGF-β)
These growth factors have been shown to have a powerful effect on hair follicles, promoting cell proliferation, differentiation, and angiogenesis . For instance, VEGF is a potent hair growth stimulator that induces angiogenesis, while IGF-1 prolongs the anagen phase of the hair growth cycle .
Cellular Signaling Pathways
The growth factors and cytokines in PRP activate various cellular signaling cascades that contribute to hair follicle stimulation and regeneration. Some key pathways include:
ERK Signaling: PRP activates the extracellular signal-related kinase (ERK) pathway, which promotes the proliferation of dermal papilla cells .
Wnt/β-catenin Pathway: PRP upregulates β-catenin signaling, which is crucial for hair follicle development and cycling .
Akt Signaling: The activation of Akt signaling by PRP has anti-apoptotic effects, prolonging the survival of dermal papilla cells .
EGFR Pathway: PRP constituents, such as prolidase (PEPD), can interact directly with the epidermal growth factor receptor (EGFR), inducing EGFR-dependent signaling [4].
PI3K/Akt/mTOR Axis: PRP treatment increases the levels of total and phosphorylated forms of proteins in this signaling axis, promoting cell growth and proliferation [4].
These signaling pathways work in concert to stimulate hair growth by inducing follicular stem cell differentiation, prolonging the anagen phase, and enhancing cell survival.
Effects on Hair Follicle Cells
PRP exerts multiple beneficial effects on various cell types within and surrounding the hair follicle:
Dermal Papilla Cells: PRP induces the proliferation of dermal papilla cells, which are crucial for hair follicle function and cycling .
Stem Cells: Growth factors in PRP act on stem cells in the bulge area of the follicles, stimulating the development of new follicles [5].
Keratinocytes: PRP accelerates the proliferation and migration of keratinocytes, which are essential for hair shaft formation [4].
Endothelial Cells: VEGF in PRP promotes angiogenesis, increasing the number of small blood vessels around hair follicles [6].
Fibroblasts: PRP stimulates fibroblasts to produce extracellular matrix components, supporting the hair follicle structure .
The combined effects of PRP on these cell types result in:
Increased hair follicle count and density
Prolonged anagen phase of the hair growth cycle
Enhanced hair shaft thickness
Improved vascularization around hair follicles
Reduced apoptosis of hair follicle cells
Microscopic examination of PRP-treated scalp tissue has revealed an increase in the number of follicular bulge cells, hair follicles, epidermal thickening, and a higher number of Ki67+ basal keratinocytes compared to placebo-treated areas [7].
In conclusion, PRP stimulates hair growth through a complex interplay of growth factors, signaling pathways, and cellular responses. By promoting cell proliferation, extending the anagen phase, and enhancing blood supply to hair follicles, PRP offers a promising approach to hair restoration and regeneration.
The PRP Hair Treatment Process
Initial Consultation
The PRP hair treatment process begins with an initial consultation. During this crucial step, a board-certified dermatologist or hair restoration specialist evaluates the patient's hair loss and overall health to determine if PRP therapy is a suitable option [1]. The expert examines the treatment area and identifies the underlying cause of hair loss, which is essential for developing an effective treatment plan .
Blood Collection and PRP Preparation
Once the patient is deemed a suitable candidate for PRP therapy, the next step is blood collection. A small amount of blood, typically ranging from 10 to 60 mL, is drawn from the patient's arm . The blood is then placed into tubes containing an anticoagulant, such as acid citrate dextrose or sodium citrate, to prevent premature clotting and platelet activation .
The blood sample undergoes a centrifugation process to separate its components based on specific gravity. This process results in three distinct layers:
The bottom layer containing red blood cells and leukocytes
The middle layer, known as the buffy coat, rich in platelets and white blood cells
The top layer consisting of platelet-poor plasma (PPP)
The platelet-rich plasma is then extracted from the middle layer. The concentration of platelets in PRP is typically two to six times higher than the normal platelet count, which is considered optimal for therapeutic outcomes [4].
Injection Techniques and Protocols
Before administering the PRP injections, a topical anesthetic may be applied to the treatment area to minimize discomfort [5]. The prepared PRP is then injected into the scalp using one of two main techniques:
Subdermal depo bolus injections: This method involves injecting PRP as small deposits beneath the skin, allowing for diffusion and requiring fewer injections [6].
Intradermal injections: In this technique, PRP is injected directly into the dermis at a concentration of approximately 0.1 cc/cm² in the affected areas [7].
The injection process is relatively quick, typically taking less than 30 minutes to complete [8].
While there is no standardized protocol for PRP hair treatment, many practitioners follow a general treatment schedule:
Initial phase: Monthly sessions for the first three months
Maintenance phase: Sessions every three months for the first year [9]
This results in a total of six treatment sessions in the first year, occurring at months 1, 2, 3, 6, 9, and 12 [9].
It's important to note that PRP is often recommended as a complementary treatment for androgenetic alopecia. Patients are encouraged to continue using other hair loss therapies, such as minoxidil or finasteride, as PRP does not address the hormonal component of hair loss .
After the treatment, patients may experience mild discomfort, swelling, or redness at the injection sites, but these side effects typically subside within a day or two . There is usually no downtime required, allowing patients to return to their normal activities immediately after the procedure [14].
Efficacy of PRP in Different Hair Loss Conditions
Male Pattern Baldness
Platelet-rich plasma (PRP) treatment has shown promising results in addressing male pattern baldness, also known as androgenetic alopecia (AGA). This condition affects approximately 50% of Caucasian men by the age of 50 years [1]. Multiple meta-analyzes have demonstrated the efficacy of PRP injections in increasing hair count and density. One study involving 177 patients revealed a significant increase in the number of hairs per cm2 after PRP injections compared to control groups, with a mean difference of 17.90 (95% CI 5.84–29.95, P=0.004) [1].
The effectiveness of PRP in male pattern baldness is attributed to its ability to activate the WNT/β-Catenin signaling pathway, which promotes hair follicle cell proliferation and differentiation [1]. This counteracts the suppression of canonical WNT signaling caused by dihydrotestosterone in dermal papilla cells, which is responsible for defective hair growth and retarded hair cycling in AGA [1].
Female Pattern Hair Loss
Female pattern hair loss (FPHL) is the most common cause of hair loss in middle-aged women, characterized by progressive follicular miniaturization and conversion of terminal follicles into vellus-like follicles [1]. PRP has demonstrated positive effects in treating FPHL, as evidenced by several studies. A systematic review comprising 92 patients from 6 randomized controlled clinical trials showed that PRP has a positive effect on FPHL treatment by increasing hair thickness and hair density [1].
A meta-analysis involving 776 female participants from 16 randomized controlled trials and 26 observational trials demonstrated that PRP has a good therapeutic effect on FPHL in terms of hair density compared to control groups (OR 1.61, 95% CI 0.52–2.70) and compared to baseline (OR 1.11, 95% CI 0.86–1.37) [1]. Moreover, PRP treatment has been associated with high levels of satisfaction and improvement in the quality of life for patients affected by FPHL [1].
Alopecia Areata and Other Types
Alopecia areata (AA) is an autoimmune disorder causing nonscarring alopecia in both males and females, with a lifetime risk of around 2% [1]. PRP has shown potential in treating AA due to its anti-inflammatory effects and ability to suppress cytokine release [1]. A randomized, double-blind, placebo-controlled study involving 45 patients with AA demonstrated that PRP significantly increased hair regrowth and Ki-67 levels (a marker for cell proliferation) compared to triamcinolone acetonide or placebo injections [1].
Several randomized controlled trials have shown that PRP can stimulate hair regrowth to a similar extent as intralesional injection of triamcinolone acetonide in AA treatment [1]. However, some studies have found that PRP may be less effective than intralesional steroid injections, possibly due to the stronger immunosuppressive effect of steroids on T lymphocyte activation [1].
PRP has also shown promise in treating other types of hair loss, including telogen effluvium . It has been reported to be effective in improving hair growth, hair count, and hair thickness in patients with various forms of alopecia .
In conclusion, while PRP has demonstrated efficacy in treating different types of hair loss, including male pattern baldness, female pattern hair loss, and alopecia areata, it's important to note that treatment protocols and preparation methods can vary. This variability may influence the effectiveness of PRP therapy . Further standardization of PRP preparation and administration methods could help optimize its efficacy across different hair loss conditions.
Combining PRP with Other Hair Restoration Techniques
PRP and Hair Transplantation
Platelet-rich plasma (PRP) therapy has shown promising results when combined with hair transplantation techniques. Several studies have demonstrated the beneficial effects of this combination. In one experimental study involving 20 patients with male pattern baldness, areas pretreated with PRP showed a 15% greater hair yield in follicular unit density compared to areas treated with normal saline (18.7 follicular units per cm2 vs 16.4 follicular units per cm2) [1].
Another comparative study revealed that transplanted follicular unit grafts in conjunction with platelet lysate (PL) or activated PRP (AA-PRP) resumed growth faster than those treated with normal saline. At four months post-operation, 99% of follicle regeneration had occurred in PL-treated areas, 75% in AA-PRP-treated areas, and 71% in saline-treated areas .
Furthermore, a randomized controlled study showed that preserving hair grafts in PRP before implantation enhances hair density, graft uptake, and hair thickness compared to preservation in normal saline . PRP has also been successfully combined with follicular unit extraction (FUE) hair transplantation. A single-blind, prospective randomized study involving 40 FUE hair transplant patients demonstrated that intra-operative PRP therapy significantly improved hair density and quality, reduced catagen loss of transplanted hair, and promoted faster recovery and appearance of new anagen hair .
PRP and Low-Level Laser Therapy
The combination of PRP therapy and low-level laser therapy (LLLT) has emerged as a powerful option for treating hair loss, particularly in cases of female pattern hair loss. LLLT has been used for over 20 years to treat female hair loss and has shown to prolong the growth phase of hair follicles and increase blood flow to the follicles, reversing miniaturization and leading to thicker, healthier hair .
When combined with PRP, LLLT can enhance the overall effectiveness of the treatment. While both therapies have shown efficacy on their own, they work in different ways to heal the hair follicle, providing patients with a better chance of success and stronger results . Some clinics recommend using industry-leading laser cap devices that provide optimal energy and output, as research has shown these to be necessary for effective hair loss treatment .
PRP and Topical Treatments
Combining PRP with topical treatments, such as minoxidil, has shown promising results in the treatment of androgenetic alopecia (AGA). A comparative study evaluated the clinical efficacy of minoxidil, PRP therapy, and their combination in men with AGA. The study divided patients into three groups: one receiving a combination of 5% minoxidil solution and PRP injections, another receiving PRP injections alone, and a control group receiving only 5% minoxidil solution .
The results demonstrated that the combination therapy significantly exceeded the clinical effects of both PRP monotherapy and topical minoxidil applications. The effectiveness of the combined therapy surpassed traditional minoxidil therapy in terms of hair density by 1.74 times, hair shaft thickness by 14.3 times, proportion of telogen hair by 9.3 times, and the share of vellus hair by 19.1 times .
Moreover, the effects of combination therapy exceeded those of PRP monotherapy in terms of hair density by 2.9 times, hair shaft diameter by 2.2 times, and the share of telogen hair by 2.9 times . These findings suggest that PRP and minoxidil potentiate each other's actions when used together, making their combined application a promising approach for treating androgenetic alopecia .
In conclusion, combining PRP with other hair restoration techniques such as hair transplantation, low-level laser therapy, and topical treatments has shown significant potential in enhancing the overall efficacy of hair loss treatments. These combinations offer synergistic effects, leading to improved hair growth, density, and quality for patients seeking effective solutions for hair restoration.
Safety Profile and Potential Risks of PRP Hair Treatment
Platelet-rich plasma (PRP) hair treatment is generally considered a safe and low-risk procedure. However, as with any medical intervention, it is essential to understand the potential side effects and safety considerations associated with this therapy.
Common Side Effects
While PRP injections are typically well-tolerated, patients may experience some minor and temporary side effects. These commonly include:
Pain and discomfort at the injection site
Bruising and redness
Swelling and inflammation
Itching
Temporary discoloration of the treated area
These side effects are usually mild and resolve within 2-5 days following the treatment [1]. Some patients may also experience a tingling sensation during the activation of platelets .
It is important to note that every individual reacts differently to injection therapies [1]. In rare cases, more severe side effects may occur, such as:
Infection
Nerve injuries
Tissue damage
To manage discomfort, patients can take Tylenol or other acetaminophen-containing products as directed . It is advisable to avoid applying ice to the injected area, as it may interfere with the inflammatory process crucial for the treatment's effectiveness .
Long-term Safety Considerations
While PRP therapy has shown promising results in treating hair loss, long-term safety data is still limited. However, the use of autologous platelets significantly reduces the risk of allergic reactions compared to other injectable medications like corticosteroids .
To ensure optimal safety and efficacy, patients should:
Choose a qualified healthcare professional for the procedure
Disclose their complete medical history and current medications
Follow post-treatment care instructions carefully
Attend follow-up appointments as scheduled
Contraindications and Precautions
Certain conditions and factors may increase the risk of side effects or contraindicate PRP treatment. Patients should not undergo PRP hair treatment if they have:
Blood disorders or bleeding disorders (e.g., hemophilia, thrombocytopenia)
Skin cancer or systemic cancer
Active skin infections or open wounds in the treatment area
Pregnancy or are breastfeeding
Certain autoimmune diseases
Additionally, patients should inform their healthcare provider if they:
Are taking blood thinners or nonsteroidal anti-inflammatory drugs (NSAIDs)
Have recently undergone steroid therapy
Have a history of blood clotting disorders
It is crucial for patients to consult with a healthcare professional before starting PRP treatment to assess their individual risk factors and determine if they are suitable candidates for the therapy .
In conclusion, while PRP hair treatment is generally safe and well-tolerated, patients should be aware of potential risks and follow their healthcare provider's instructions carefully to minimize complications and achieve optimal results.
Conclusion
PRP hair treatment has emerged as a promising approach to combat hair loss and promote regrowth. This innovative therapy harnesses the power of the body's natural healing processes, offering a safe and effective alternative to traditional hair restoration methods. By utilizing a patient's own platelets, PRP treatment stimulates hair follicles, extends the growth phase, and improves overall hair density and thickness. Its effectiveness in treating various types of hair loss, including male and female pattern baldness, has been supported by numerous scientific studies.
The combination of PRP with other hair restoration techniques has shown even more impressive results. Whether used alongside hair transplantation, low-level laser therapy, or topical treatments, PRP enhances the overall efficacy of these interventions. To consider PRP treatment, patients should consult with qualified healthcare professionals, such as those at Mediccess in Turkey, known for their high-quality service and patient satisfaction. As research continues to evolve, PRP hair treatment stands out as a cutting-edge solution for those seeking to restore their hair and boost their confidence.
FAQs
Is there scientific evidence supporting PRP for hair growth?
Yes, scientific studies have demonstrated positive outcomes with PRP treatments, particularly noting an increase in hair density. PRP injections have been shown to significantly boost hair growth on the scalp.
What should you know about PRP treatments for hair?
PRP (Platelet-Rich Plasma) injections are found to be effective in treating conditions like male pattern baldness by both preventing hair loss and encouraging new hair growth. Additionally, PRP can enhance hair regeneration following hair transplants.
How effective is PRP in restoring hair?
PRP hair restoration is highly effective. It not only prevents hair loss and thinning but also stimulates the regrowth of hair, leading to thicker and healthier hair.
Can PRP rejuvenate hair effectively?
PRP hair rejuvenation has proven effective, particularly when compared to drug-based therapies that require ongoing daily treatment. PRP treatments typically involve a series of injections over four to six months, followed by two to three maintenance treatments annually, which have shown to regrow and maintain hair effectively.
References
[1] - https://www.healthline.com/health/prp-for-hair-loss
[2] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8922312/
[3] - https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/plateletrich-plasma-prp-treatment
[4] - https://www.skincaredrs.com/blog/introducing-prp-hair-restoration/
[5] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9917549/
[6] - https://westoverhillsdermatology.com/unlocking-the-magic-the-timeline-of-prps-hair-transformation-journey/
[7] - https://www.pittsburghhandandnerve.com/blog/prp-for-hair-loss-how-biologics-can-regrow-your-hair
[8] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8965895/
[9] - https://www.ncbi.nlm.nih.gov/books/NBK430924/
[10] - https://www.everydayhealth.com/skin-beauty/what-platelet-rich-plasma-therapy-prp-hair-loss/
[11] - https://pubmed.ncbi.nlm.nih.gov/28216604/
[12] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7832888/
[13] - https://journals.sagepub.com/doi/10.1177/0363546516637176
[14] - https://www.selphyl.com/post/understanding-the-prp-hair-treatment-success-rate
Back