Abnormal hair loss is technically referred to as:

Alopecia is the technical term for abnormal hair loss, which can have many causes. (Trichology is the study of hair, pediculosis is a lice infestation, and canities is the technical term for gray hair.) Cosmetologists may notice signs of hair thinning or loss during services; while they can recommend gentle care and suitable styles, diagnosing the cause of significant or unusual hair loss is outside their scope and may warrant referral to a physician. Knowing the term alopecia and related hair conditions is tested hair science.