Diagnosis

Before making a diagnosis, your doctor will likely give you a physical exam and ask about your diet, your hair care routine, and your medical and family history. You might also have tests, such as the following:

• Blood test. This might help uncover medical conditions that can cause hair loss.
• Pull test. Your doctor gently pulls several dozen hairs to see how many come out. This helps determine the stage of the shedding process.
• Scalp biopsy. Your doctor scrapes samples from the skin or from a few hairs plucked from the scalp to examine the hair roots under a microscope. This can help determine whether an infection is causing hair loss.
• Light microscopy. Your doctor uses a special instrument to examine hairs trimmed at their bases. Microscopy helps uncover possible disorders of the hair shaft.