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UNDERSTANDING DENSITY: Meeting a Patients Expectations of Density is the Second Most important Goal in Hair Transplantation.


Meeting a patient’s expectation of density is the second most important goal in goals in hair transplantation right behind naturalness. What a patient wants to know is how much area can be covered and how thick will it look. The answer to these questions varies extensively depending on a number of factors. The good news is that if a patient is a good candidate meeting expectations of density can be achieved.

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However, meeting density expectations can be difficult due to the constraints of a limited donor supply. The amount of hair available from the donor area is limited and less then the amount of hair that originally existed in the recipient area before hair loss started. Therefore we can never re-create the true,”hair for hair”,density (hair/unit area) that existed before hair loss started. As a consequence, a critical challenge in hair restoration surgery is to create the best illusion of density at lower than normal densities. Fortunately this illusion of density or appearance of fullness can be created with much less than the original amount of hair. The maximum degree of density that can be achieved varies from patient to patient and is determined by many factors including: donor supply, current hair loss, future hair loss and hair characteristics (color curl and caliber).

To achieve maximum density a physician must have the two distinct skill sets. First he must have the skill to move large numbers of delicate grafts in a way that ensures the maximum survival and minimal waste of each precious hair. However, simply being able to move large numbers hairs is not enough. A second, equally as important is to know how to move the hair in the most effective way possible. By effective we mean utilizing patterns, distributions and techniques that create the greatest appearance of fullness with the least amount of hair. Skill and experience in these two areas will determine if a surgeon is able to enable a patient to reach his maximum potential.

Shapiro Medical Group (SMG) is an expert in maximizing density as evidenced by the frequency Dr Shapiro has been asked to lecture on this topic at international conferences around the world (See CV). Some the specific factors that influence density are discussed in more detail in the sections below.


There are many factors that influence are ability to create density but probably the most important is the relationship between the finite donor supply and the extent of current hair loss. It can be looked at as a matter of” supply and demand (donor supply vs. recipient demand). If the donor supply was un-limited, creating density in hair transplantation would be a simple task and we could create a full head of hair on everyone. Unfortunately this is not the case. The donor supply varies significantly from patient to patient and is usually less than the amount needed to restore a bald area to the density that originally existed before hair loss started, especially in patients with extensive hair loss.


  • Average total donor supply hair can range from 4000 TO 8000 (or more) grafts.
  • The total recipient area in full male pattern balding (front and crown) may have had as much as 20,000-25,000 FU’s before hair loss started.
  • Comparing 8000 to 20,000 shows there is simply not enough donor hair to restore a full male pattern balding area “hair for hair” to its original pre-hair loss level.

Luckily, for reasons that will be explained later, a very good appearance of fullness can frequently be created within the constraints of this limited donor supply. If this was not true hair transplantation could not be done as successfully as it is today.

Most patients have enough donor hair to restore the appearance of fullness to the front two thirds (excluding the crown) of a totally bald scalp. Many patients can also obtain some coverage of their crown to varying degrees. Unfortunately there are patients that simply do not have enough donor hair to address their crown. And in extreme cases a patient may not be a candidate for hair restoration surgery at all. A similar situation exists with respect to hairline placement. Some patients need to keep a higher mature hairline while others have enough donor hair to be more aggressive and create a lower hairline. In general, if the donor supply is high and the severity of hair loss low good coverage can be provided in all areas of concern. However if the donor supply is low and balding area large the achievable coverage will be much more limited.


  • Good Candidate

    Good Donor- Average Recipient Area

  • Poor Candidate

    Poor Donor- Large Recipient Area


Another factor that influences density is future hair loss. Hair loss can progress at an unpredictable rate. Patients with mild hair loss today may have severe hair loss in the future. Physicians need to be careful to transplant hair in a pattern that will look natural not only today but also if the hair loss progresses and recedes away from the transplanted area. Areas of thinning that improved when initially transplanted may become thin again in the future as native hair is lost. In addition unnatural patterns may develop if native hair recedes away from transplanted hair as a patient ages. Patients need to be educated about the possibility of needing more work in the event of hair loss progression.

Physicians also have to leave enough donor hair has in reserve to treat any possible progression.It is very hard to predict how severe a patient’s final pattern will be when they are young. Family history helps a little but is not very reliable. Probably the best predictor is the age and severity at which hair loss begins. A patient that develops significant hair loss at a very early age will most likely end up with severe hair loss while patient that only begins to recede in his 40’s or 50’s will most likely have less severe pattern.


Hair Loss is Progressive & Unpredictable

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    Age 14

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    Age 32

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    Age 40

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    Age 60

Poor Planning Leads to Future Problems

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Patients that have the potential for severe hair loss or have more limited donor CAN do hair transplants. They just have to have more realistic expectations and create a plant that is more conservative and achievable with the amount of donor hair they have. Below is an example of a Type 7 patient who achieved a pleasing result by utilizing a proper conservative plan.


  • Age 27


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  • Age 50


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  • Conservative Plan


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  • Pleasing Result


A clinic needs to estimate and take into consideration a patients potential for future hair loss when planning and predicting coverage. In addition a clinic should try to minimize future hair loss as much a possible with the use of modern medications such as Rogaine and Propecia.

HAIR CHARACTERISTICS: The effect of Color, Curl, & Thickness

Curly hair and higher caliber (thicker) hair is more effective at creating the appearance of fullness because these characteristics increase the amount of hair surface area, in a given volume of space, that is interposed between the scalp and eye. This means the same amount of curly or thick hair will do a better job of hiding the scalp than thin straight hair. Although a physician can’t control thickness or curl, he does need to take these factors into consideration when predicting the results a patient can achieve. In addition patients may be able to improve their look by using products or medications that will increase the thickness or curl of their hair. Propecia© and Rogaine© owe a lot of their affect to the ability to thicken all the existing hair on a patients scalp. By the same token putting a slight waver or curl in a patients hair may also increase the illusion of density.

Hair color also influences the appearance of density. We see the scalp through the hair partially because we notice the contrast between the color of the hair and the color of the scalp. This is very obvious with strong contrast such as exists with black hair and white skin. However, when there is a low color contrast between the hair and scalp (such as with light blond hair on light skin) it is much more difficult to notice this contrast. This makes it more difficult to notice thinning and increases the illusion of density. Products such as Dermatch© which color the scalp exert their effect in this manner A physician does not have control over this factor but patients can use products or even color their hair in of modern medications such as Rogaine and Propecia


There is a fortunate truth in hair transplantation that helps with density. The “truth” is that the hair can maintain a normal “appearance of fullness” until a patient loses approximately 50% of our original hair. This long held and widely accepted dermatological concept was verified in a study by Dr. Manny Marritt who demonstrated that “parted” hair in a 1cm area did not begin to appear “thin” or to “widen” until approximately 50% of the original hair was lost. From clinical experience the amount of hair that can be lost before hair appears thin will vary slightly between 40% and 60%. A patient with very good hair characteristics (i.e. coarse, curly, light colored hair) may maintain an appearance of fullness until he loses 60% of his native hair. On the other hand a patient with poor hair characteristics (i.e. fine, straight, black hair) may begin to appear thin with as little as 40% hair loss.The take home message however is that same principle applies in reverse when surgically replacing hair. In other words we only need to replace hair to approximately 40-60% of its original volume (depending on hair characteristics) to create an appearance of fullness. A corollary to this principle is that it is potentially ‘wasteful’ to replace a thinning area to greater than 50% of its original density. Replacing hair to greater than 50% of pre-hair loss levels will give only minimal aesthetic improvement and runs the risk of depleting the limited donor supply and depriving the patient of the ability to use the hair in other areas in the future.

The appearance of hair loss seems to change as we cross certain important “thresholds” . Below is a description of the appearance of thinning that occurs as we lose our hair and cross certain thresholds.




NORMAL DENSITY (80-100FUCM2): Normal Density is usually 80 to 100 FU/CM2. Some patients can have higher or lower densities
UNDETECTABLE HAIR LOSS (50-80 FU/CM2): For most patients as they decrease from 80 to 50 FU/CM2 their hair still looks full under most situations. A patient does notice any thinning at this phase but, from a practical standpoint the hair loss is “undetectable” . Hair characteristics influence at what point hair loss will be detectable. Patient with very poor hair characteristics may notice thinning earlier at 55-60 FU/CM. On the other hand, patients with great characteristics may not notice thinning unit they have only 40 FU/CM2.
Early Thinning or (25-50 Fu/cm2): In general our hair begins to look thin when we drop below ~ 50FU/CM2. This is the point when a person looks in the mirror one day and he wonders if his hair is looking thin and the next day it looks fine. I call this the phase of “situational” hair loss hair loss t because it is the point where the hair begins to look thin under different situations. For example the hair looks full when dry but thin when wet. Or hair looks full in low light but thin under bright light. During this phase people can do things to camouflage the thinning like blow dry their hair. As one moves from 50 FU/CM down to 25 FU/CM the number of situations during which the hair appears thin increase
**THRESHOLD 2Late Thinning ( 10-25 FU/CM2): When a patient drops below 20 to 25 FU/DM2 the basically look thin all the time. They still look like they have hair but it is see through all the time. When they drop below 10 FU/CM for all practical purpose they look bald.

Another concept that is important to understand is the concept of “social observation” vs. “critical observation”. A hair transplant that achieves a density of 40-50 FU/cm2 will achieve social fullness, which means that the patient will look full most social situation. This includes casual observation from across the room to about a foot away. It is not meant to eliminate the ability to see any scalp under all“critical” observations which mean very close up, orparted. If one critically examines the scalp of people without hair loss, some scalp can be often seen.Patients who agonize about never seeing any scalp under any situation have unrealistic expectations about the purpose of hair transplants and will never be satisfied. A patient can be made to look full under most situations… but the scalp can be found under critical close up observation


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“Thank you very much for your attention. I am very happy with the results of the surgery. After 3 months only I already have full hair coverage in all the affected areas and don’t need to use the hair clips like I used to do for many years. Please give my beast regards to Dr. Shapiro and the team...”Read More

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