Hair and scalp evaluation techniques can be classified into 3 categories: noninvasive methods (clinical history, general examination, inspection and palpation of the hair and scalp, photography, dermoscopy, etc.); semi-invasive methods (the trichogram); and invasive methods (biopsy).

A trichogram is a semi-intrusive method of hair analysis that involves plucking 50 to 100 hairs from different parts of the scalp, sticking them to a slide and examining them under a microscope. The aim is to determine the rate of hair loss progression by establishing how much of your hair is in each of the three stages of the hair growth cycle ...

There are many resources available for the assessment of patients who present with hair loss. Evaluations can be categorized as invasive (eg, scalp biopsies), semi-invasive (eg, trichogram), or noninvasive (eg, hair counts, microscopic evaluation, trichoscopy).

This semi-invasive technique is commonly employed to evaluate hair loss. It allows the analysis of the proportion of hair in different phases of the cycle. The patient should not wash their hair for 3 days prior to examination.

We discuss three different categories of hair evaluation options: invasive methods (biopsy), semi-invasive methods (trichogram) and noninvasive methods.