6 Year Old Developed Very Smooth Bald Spot

My 6 yr old son has developed a small, oblong bald spot around 3 months ago. The spot has no signs of hair growth and is very smooth as if no hair was ever there. What could be the cause and should I take him for blood work?

You should have it look at by a good dermatologist. The possibilities are extensive, and infections are not uncommon. Ringworm (a fungal infection) is one of the more common causes in a six year old.