Alopecia areata is diagnosed through a medical history and physical examination. Your doctor will ask you questions about your hair loss, look at the pattern of your hair loss, and examine your scalp. And he or she may tug gently on a few hairs or pull some out.
If the reason for your hair loss is not clear, your doctor may do tests to check for a disease that could be causing your hair loss. Tests include:
Hair analysis. Your doctor will take a sample of your hair and examine it under a microscope. A scalp sample is also sometimes taken.
Blood tests, including testing for a specific condition, such as an overactive or underactive thyroid gland (hyperthyroidism or hypothyroidism).