Dr Kerryn Phelps, Health Editor, Channel Nine, 'Today'

PHELPS: Good morning Tracey.

GRIMSAHW: Lets start talking about men. Why do some men go bald and not others, and is it their mothers fault?

PHELPS: This is one area where you can blame your parents, but not necessarily your mother. There is certainly no question that in male pattern baldness that testosterone is the culprit, because we know that if a male is castrated that he wont lose his hair. Now, that's a little bit of an excessive way to prevent baldness, so we do need to look at perhaps other ways of protecting hair.

GRIMSHAW: The baldness gene, if indeed there is one, is it true that it is carried by women, by mothers?

PHELPS: It can be carried by either side, but what's interesting is that baldness can occur in men and women. If you're looking at the male type of pattern baldness, and this is the common type of baldness, they'll lose their hair around the hair line, and around the crown. Whereas in women, who can also lose their hair in this way, in terms of pattern baldness, will loose it in terms of thinning all over the scalp.

GRIMSHAW: In the case of women, is it testosterone?

PHELPS: No, it's not. It's where the hairs themselves, they will be lost but they don't regenerate at the same rate, and that generally comes on with age, although hair loss can actually start in your teens.

GRIMSHAW: If you start losing hair and you don't have a family history of it, what other causes could there be?

PHELPS: There is a whole vast range of causes, and this is really quite interesting because, if you are suddenly losing your hair and you don't know why and it doesn't seem to be running in your family, you do need to look for causes. Illnesses like diabetes, Lupus, which is an auto-immune disease, thyroid disorders can cause it, you can also…

GRIMSHAW: We have a list, perhaps we can pop that list up…

PHELPS: Sure, women who have a baby, after pregnancy, quite often find that they lose their hair for up to a year afterwards, so hormonal changes can do it. If you've had a serious illness, a flu for example or a high fever, or surgery you can lose your hair for up to several months later. Obviously, if you've had chemotherapy or radiotherapy, poor nutrition, women, or men who go on fad or crash diets, particularly if they are low in iron, they can actually lose their hair because of that. If people have excessive shampooing and blow drying of their hair it can actually damage the hair follicles, emotional and physical stress can precipitate it as well. And in children, if they suddenly seem to be losing their hair in patches, it might be because they're under stress and they are pulling their hair out.

GRIMSHAW: If it's say something like stress, that may be a short term thing, or perhaps you've been stressed for a particular reason for a few months, and you elevate the stress, does your hair grow back, or is it gone forever?

PHELPS It grows back eventually, once the precipitating factor is gone, and sometimes people find once the medication that they have been started on, that creates the hair loss, and there is a whole range of medications that can do this, from antidepressants to blood pressure medications, as well as the chemotherapy type drugs. Then, people will find, sometimes even if they stay on the medication, the hair loss will continue for a period of time and then it'll start to grow back, but other people will find that so distressing that they'll have a change of medication.

GRIMSHAW: What's a reasonable amount of hair to lose in a day, and how much should make you sit back and think 'I better do something about this'?

PHELPS: Each person has an average of a hundred thousand hairs on their head, and you can expect to loose between fifty and a hundred hairs each day, and each hair is on your head for about an average of four and half years, and then it goes through a resting phase of several months, and then the hair will fall out, and then a new hair will regrow, if it is going to regrow.

GRIMSHAW: It's astonishing, we know so much about how quickly hairs grow and how often we lose them, isn't it?

PHELPS: And little we know about what to do about it.

GRIMSHAW: Yeah.

PHELPS: There are some medications that are available. There's a drug call Minoxidil which was originally a heart disease medication, but is available in lotion form and you can rub it on your hair and it will grow back - not the same quality of hair - it is sort of downy, almost like baby hair, yet a lot of men find that is quite useful just to cover up bald patches, but it only works while you are using it. If you stop using it the hair will fall out again. There is also another drug which will block testosterone and some men will find that that will help stop the hair loss, but it will also affect their sexual function, so it's quite often a side effect that they're not happy at all to be involved with. Other people head for surgery and some people will be quite happy with one of the newer technology hair pieces

GRIMSHAW: The fusion things, they seem to be popular these days, too.

PHELPS: There is all sorts of methods.

GRIMSHAW: Some people go - and I guess I'm speaking mostly about men here - some people will go shiny bald, and some people will go fluffy bald. What makes the texture of the hair change if there is a follicle there, and it's growing hair, why does it suddenly change texture?

PHELPS: I don't think we know the answer to that one, and it's quite interesting. I've spoken to a large number of people who have had chemotherapy and their hair has all fallen out, and they might have had red curly hair, and when it's grown back its, grown black or silver or a completely different colour and texture. So we don't know a lot about what actually happens in the hair follicle to make it change that way. But there's another type of hair loss which is a type of auto-immune disease where the hair actually falls out in circular clumps called alopecia, and that one can just keep on happening for about six months to two years, and then that will all just grow back again, as it was before.

GRIMSHAW: We know a lot about what happens, we don't know how to fix it, but thanks Kerryn.

PHELPS: Thank you.

Ends