Are newly growing hairs thinner than mature ones?

Newly Growing Hairs

The "miniaturization" of hairs refers to a process where hairs get thinner and thinner over time. It is frequently seen in hairs from the scalps of individuals with androgenetic alopecia (male balding and female thinning). The confirmation that a given person has miniaturized hairs frequently evokes a great amount of worry and questions about whether the individual does in fact have androgenetic alopecia. One must always keep in mind that a few conditions can produce thinner hairs - and one must not be too quick to jump to the conclusion that the patient has androgenetic alopecia.

Telogen effluvium is a hair shedding condition where hair sheds from factors such as low iron, stress, thyroid disorders or crash diets. As the hairs start growing back, they appear smaller at first until they thicken up over time. A patient with a consider number of newly regrowing hairs could be mistaken for having miniaturization due to androgenetic alopecia.

When one looks at the following picture of two trees, one can appreciate that the tree on the right is probably older than the one on the left. There is no reason to believe that with time the tree on the left won't achieve the same thickness as the tree on the right.

In cases of massive telogen effluvium, hairs thicken up to some degree over time. Re-evaluation of the patient's scalp a few months later can be helpful if one is unsure whether the patient has a TE, AGA or both.