Dr Thomas Stuttaford's next online forum will be live after 1pm on March 12. The topic is: stroke prevention and treatment. To ask the doctor your question on this topic and to read other recent topics he has answered click here

Q1: My daughter suffered from rickets as a baby and she was treated with high dose of vitamin D, sunlight had been prescribed by her paediatricians in this regard. We followed all the instructions accordingly. For example to keep her in the sunlight for twnty minutes. After she was diagnosed with rickets we all got our blood tested for vitamin D and found our levels were extremely low. Even after having had the high dose of vitamin D (600000 iu) we are all at the boarder level which is around 40 nmol/l. It is really confusing the way media portrays the effects of sun exposure. I am now concerned about keeping my daughter in the sunlight and when I do so I feel as if I am doing something wrong. This may be because the ads about the dangers of sun exposure overtake those about the benefits of sunlight. Your answers are interesting, but I am not exactly getting an appropriate message as our family members are all of brown skin. Please help. At the time of diagnosis of rickets we lived in New Zealand and we currently live in Australia. Kamalini Kathir

A1: Thank you for your question. It raises a very important medical point. The dilemma is how to balance the need for absorbing enough sunlight to protect bones by laying down an adequate supply of vitamin D without running the risk of sustaining sunburn, and with it the hazard of skin malignancies later in life. As you rightly say the recent emphasis has understandably been on skin protection. I knew one well-known dermatologist who forbade his children to go out into the sun and kept the curtains drawn in his house all day. Achieving the correct balance affects not only the parents of small children but people of every age group and skin type. The anxiety about skin cancer is naturally at its most intense in Australia and in New Zealand for both countries were at one time heavily populated by fair skinned blond or reddish haired Celts from Scotland or Ireland. These skin types are especially vulnerable to sunburn. Furthermore the sun in the antipodes is much more intense than in Northern Europe. However being in an Australian or New Zealander doesn't protect against cancers such as prostate, breast, ovarian, and colon and nor will it ensure someone has adequate vitamin D manufactured from the body by sunlight unless they spend enough time out of doors.

Judging from your name I would be surprised if you were a Celt especially as you say you have brown skin. People of brown skin need thirty times as much sun as those fair skinned people whose ancestors originated in Northern Europe. Twenty minutes a day would be enough for your Celtic neighbours but not enough for your daughter. She would need at least an hour or two. The other problem is one of clothing. I don't know what your religion is but those religions in which it is customary keep much of the skin covered also need more sunlight than those who regularly have their sleeves rolled up, wear shorts, and have their faces exposed to the elements.

As well as providing more sunlight for your daughter you must also give her a diet rich in calcium and vitamin D. Adult members of your family shouldn't only be tested for vitamin D levels but should also have their bone density estimated. The diet in your household should be rich in dairy produce, eggs and fish. You should talk to your doctor about calcium and vitamin D supplements.

Those people who live in Britain rather than Australia might like to obtain a leaflet by emailing leaflet@realfactsoflife.co.uk or speak with a nurse from the National Osteoporosis Society on 0845 130 3076

Q2: The joint within my thumb (extensor pollicis longus) seems to become partially disconnected for no apparent reason and requires me to bend my thumb forward slightly to click it back into place with an audible sound similar to clicking ones fingers. This has happened since I was a teenager, I am 21 now and my GP suggested it was just flexibility within the joints and not to worry. However while it is not particularly painful it occurs several times a day and I am worried it will lead to arthritis or a lack of mobility in the future. Please could you advise me whether this would be the case and what course of action to take? Olly Clegg

A2: Without seeing your hand and thumb it is impossible to give a certain diagnosis. However the description you give could well be that of a trigger finger or trigger thumb. Usually in adults this trouble affects the fingers of adult women. In it the fibrous sheath around the tendon becomes thickened and this in turn distorts the tendon so it no longer slides easily within its sheath.

In children the digit that is affected more often than the fingers is the thumb. I notice that your thumb troubles started in your teenage years, this is rather later than usual. Trigger fingers and thumbs are very easily corrected by orthopaedic surgeons who are able to make a nick in the fibrous sheath so that it can again slide easily and doesn't require thought or any special measures. I would suggest that you return to see your GP and discuss the problem with the doctor and the possibility of a consultation with an orthopaedic surgeon. If the trouble is a trigger thumb it isn't likely to lead to arthritis in later life.

Q3: I was diagnosed as having hypermobility syndrome by a rheumatologist and I seem to suffer daily from lots of aches and pains, not helped by the fact I spend most of my day in front of a computer. The physio at the rheumatologists surgery told me that pretty much all forms of exercise, including swimming, were risky and likely to cause pain (something I really knew from experience), but I need to do something because my sedentary job, combined with amitriptyline for pain have caused me to put on weight which is affecting my knees, hips, ankles and feet! I feel stuck in a vicious circle - surely there is some form of exercise for me to take? Sophie Ewan-Roberts

A3: There are several different type of mobility syndromes and all of them are of varying severity. The ones that I have seen most often have been the consequence of one of two inherited disorders of collagen (elastic connective tissue) formation. One of these is known as Ehlers Danlos syndrome, the other as Marfan's syndrome. It shouldn't be forgotten that the degree of normal mobility in everybody's joints differs enormously and yours may be within normal limits. My joints are, for example, so rigid that it was difficult to perform all the standard drill movements while doing army service whereas other people's joints may be so bendy, hyper mobile that they were proud of being almost double jointed.