Hair disorders are common. Whether you are losing your hair, growing hair in unwanted places, or having a problem with your scalp, these are conditions that dermatologists diagnose and treat. Hair loss can occur at all ages, and for many different reasons. Hair loss can be due to shedding or hair breaking, and there are different patterns. Some hair loss can be permanent, but others are reversible. A biopsy and lab testing may be required in many cases.