Dear Sun Doc THE SUN DOCTOR

has a line-up of specialist and general Your exciting and revealing paper your health concerns – and it is for practice doctors waiting to answer health bugs and let this week’s free! So come on, send in those nagging have to worry about revealing your Sun Doctor deal with it. You don’t fine! true identity. Give us a pseudo, it’s

I have been having a black streak line in my thumb fingernail for about a year now. What could be the underlying cause? Simon

You can get a black streak due to bleeding under the nail as a result of injury or if you are taking blood thinning medication. You can also get a dark line as a result of other health conditions including kidney disease, lung disease, problems with blood circulation or endocarditis (infection of the inner lining of the heart).You may also have melanonychia, darkening caused either by activation of melanocytes (cells that produce the pigment melanin) or by increase in the number of melanocytes. The melanocytes can be activated due to genetics (higher incidence of streaks in people from darkskinned races), pregnancy, poor nutrition, infections, inflammatory diseases, systemic illnesses, injury, medication such as chemotherapy, HIV medication and some malaria medications. Where there is increased multiplication of the melanocytes, it may be non-cancerous such as where there is a mole; or it may be cancerous, and a sample of the tissue needs to be taken to determine which it is. Most of the time, depending on the underlying cause, the darkening of the nail may be harmless and not require any treatment. Where treatment is needed, it will depend on the cause.

The entire surface of your skin is replaced every month, which put another way means you have about 1,000 different skins in your life!