Thumb nail issue

I have one thumb (left) that is cracked and concave from the center to both sides.  Color seems normal.  The nail is thin and it never grows without splitting right up the middle.  It's sore and now it's bleeding a bit through the crack.  None of my other nails are the least bit problematic.  All nails on both hands other than that left thumb are just fine and dandy.
What is wrong with my thumb?  I never hit it or banged it or injurde it in any way.
Thanks  - -
RD

[Bhupinder Kaur, MD]

Hello,

Your symptoms are suggestive of koilonychias.Koilonychia is usually caused by iron deficiency anemia.These nails show raised ridges and are thin and concave.I wouyld suggest that you get your Hb levels estimated and also take some iron supplements for some days.If the symptoms persist then pls consult a dermatologist.

Hope it helps. Take care and pls do keep me posted on how you are doing or if you have any additional queries.Kind regards.