Some conditions can cause hair loss, though in a different pattern to male pattern hair loss. If you think your hair loss is very rapid, unusual or not in the pattern described HERE, you should see your doctor. Patchy hair loss can be caused by ring worm, which is a fungal infection. The autoimmune condition Alopecia Areata can cause patches of baldness, and sometimes complete hair loss. General thinning of the hair can be caused by an underactive thyroid gland, low iron, lupus, or a side effect of various medications.