Dr. Greene, I read your comments concerning school age children's hair loss. My situation is a little different. I have an 18-month-old girl and she has been losing her hair for about 6 weeks. The dermatologist says she has symptoms of trichorrhexis invaginata and trichorrhexis nodosa. He says her nails and teeth are fine and does not expect anything more than hair loss. This hair disorder has an autosomal-recessive mode of inheritance. My husband and I have checked back at least three generations and no one has ever had anything like this. Please let me know of any information on causes and treatments you may know of. I have checked local libraries and I have to be a medical student to get information from a college library. I bought a computer hoping to find information on the internet, but your article was the closest I came. Please, if you can give me any information I would greatly appreciate it. I am very concerned and would just like to be more educated about this condition and what I can expect in the months to come. Thank you for your time.

We all know how much we hate to have a bad hair day. Our hair is an important part of our self-esteem. Advertisements for hair care products call out to us from television and magazines. When someone changes her hair, people often feel compelled to comment.

Trichorrhexis (pronounced trick-o reck sis) is not a word you are likely to hear tossed around in casual conversation. It comes from two old Greek words: trichos -- meaning hair, and rhexis -- meaning fracture. People with trichorrhexis have hair that breaks easily.

Trichorrhexis nodosa is the most common hair shaft disorder. The hair is especially fragile, owing to the presence of tiny grayish-white nodules along the shaft. People with trichorrhexis nodosa have dry, flat, short hair that breaks easily, leaving short, stubbly broken ends and patches of partial baldness. The trichorrhexis may affect only isolated patches of hair, or may affect the entire scalp. Even gentle bending of an affected hair can break it off.

Some people are born with trichorrhexis nodosa, and others acquire it along the way. The congenital form is sometimes associated with tooth or nail abnormalities, which thankfully your daughter does not have. Congenital trichorrhexis nodosa may run in families, or may occur spontaneously. When it does run in families, it is occasionally associated with mental retardation from an underlying metabolic problem (argininosuccinic aciduria -- don't worry about the name). This can be diagnosed with a urine test, but would already be evident from your daughter's development. The great majority of people with trichorrhexis nodosa have no underlying disease, and no problem other than fragile scalp hair.

The acquired form of trichorrhexis nodosa comes in two types: proximal (where the hair breaks close to the scalp) and distal (where the hair breaks farther out). Proximal trichorrhexis nodosa is common in people of African descent. Those with a genetic predisposition to this have hair that becomes more fragile in response to hair straightening, braiding, tight headwear, or harsh brushing. Distal trichorrhexis nodosa is seen mostly in people of European and Asian descent. The hair becomes more fragile with prolonged sun exposure, immersion in saltwater, or mechanical trauma. Both acquired forms of trichorrhexis nodosa will disappear within about 4 years, if the trauma to the hair shafts is stopped. In the meantime, cream rinses and protein conditioners are helpful.

Trichorrhexis invaginata, also called bamboo hair, is a rare abnormality of the hair in which the hair shaft telescopes in on itself (invaginates) at several points along the shaft. Under a microscope, the hair shaft looks like a stalk of bamboo, or a partially-lowered car antenna. The problem with the hair is that the outer wall of the shaft is too soft, allowing the distal part to slip back into the proximal part of the shaft. This rare disorder is more common in girls than in boys. It appears in infancy, and affects all the hairs of the body -- not just those of the scalp. The hair is usually dry, flat, short, sparse, and easily breakable. As yet, there is no specific treatment for trichorrhexis invaginata, but in many children it disappears by itself, beginning at about age 6.