Tests and diagnosis

Before making a diagnosis, your doctor will likely give you a physical exam and ask about your medical history and family history. Your clinician may also perform tests, such as the following:

• Blood test. This may help uncover medical conditions related to hair loss, such as thyroid disease.
• Pull test. Your doctor gently pulls several dozen hairs to see how many come out. This helps determine the stage of the hair 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. 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.