Hair can maintain a normal appearance of fullness until a patient loses approximately 50 percent of his or her original hair. This long held and widely accepted dermatologic concept was verified in a study by Dr. Manny Marritt who demonstrated that parted hair in a 1 cm area did not begin to appear thin or to widen until approximately 50 percent of the original hair was lost. From clinical experience, the amount of hair that can be lost before hair appears thin will vary between 40 and 60 percent. A patient with good hair characteristics (i.e. coarse, curly, light-colored hair) may maintain an appearance of fullness until he loses 60 percent 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 percent hair loss.

In other words, a surgeon only needs to replace hair to approximately 40 to 60 percent 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 percent of its original density. This will give only a minimal aesthetic improvement and run 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 changes as we cross certain important thresholds. Below is a description of the appearance of thinning that occurs as we lose hair and cross these thresholds.

NORMAL DENSITY (80-100 FU/CM2)

Some patients can have higher or lower densities.

UNDETECTABLE HAIRLOSS (50-80 FU/CM2)

For most patients, as they decrease from 80 to 50 FU/CM2  their hair still looks full under most conditions. A patient doesn't notice any thinning at this phase and, from a practical standpoint, the hair loss is undetectable. Patients with poor hair characteristics may notice thinning earlier at 55-60 FU/CM. Patients with good characteristics may not notice thinning unit they have only 40 FU/CM2.

THRESHOLD 1

Early Thinning (25-50 FU/CM2)

In general, hair begins to look thin when it drops below 50 FU/CM2. This is the point when a person looks in the mirror and wonders if his hair is looking thin and the next day it looks fine. We call this the “situational” hair loss phase because the hair begins to look thin under different situations. For example, the hair looks full when dry but thin when wet, or full in low light but thin in bright light. During this phase, people can do things to camouflage the thinning like blow drying their hair. As one moves from 50 FU/CM down to 25 FU/CM, the number of situations during which the hair appears thin increases.

THRESHOLD 2

Late Thinning (10-25 FU/CM2)

When a patient drops below 20-25 FU/CM2, the hair looks thin and see-through all the time. When they drop below 10 FU/CM, they look bald.