What characterizes trichorrhexis nodosa?

Trichorrhexis nodosa is characterized by brittleness and the presence of nodular swellings along the hair shaft. This condition is an indication of structural damage to the hair, where the hair strands become weak and prone to breakage due to these nodules. The nodular swellings represent localized points of weakness, which contribute to the hair's brittleness and increased likelihood of split ends and breakage. Understanding this condition is vital for estheticians, as it informs the appropriate care and treatment options to improve hair health.

The other choices describe conditions that do not specifically relate to trichorrhexis nodosa. Shiny hair with no dandruff suggests healthy hair rather than a damaged state. Scalp irritation and itching may indicate scalp conditions like dermatitis or fungal infections, and faded hair color typically relates to factors such as chemical treatments or sun exposure rather than structural hair damage.