Thumb nail

I am a 45 yr old man. Since I could remember my right thumb nail has had ridges on it. My right thumb nail is slightly darker than my left, but not totally black.  Also it looks flakey.  The nail looks like it has been slammed in a door.  The nail grows ok from the bottom and just when I think the new nail will be okay it turns the same way as if something is wrong under the nail.       All of my other nine fingers are ok.  Noone else in my immediate family share this problem.  I have been a chronic nail biter most of my life.  Since I do a great deal of hand shaking and use my right hand to do so, it has become very embarrasing.  If there is any suggestions please share.  I have been dealing with this for some time now and its mentally frustrating.  I have read post comments but none seem to fit my problem.      

[Bhupinder Kaur, MD]

Hello,
This horizontal ridge can be due to Beau’s lines. They are horizontal and going across the nail. It may be caused by an infection or problem in the nail fold, trauma, coronary occlusion, hypocalcaemia, skin disease, and may be a sign of systemic disease. It may also be caused by an illness of the body, such as diabetes, psoriasis or certain medicines. I would like you to consult a dermatologist and get investigated for all these causes.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.