To diagnose female pattern hair loss, a physician will take the patient’s medical history and perform a physical examination, during which time the scalp will be closely examined for signs of disease (e.g., scarring, plugging of hair follicles).

Other causes of diffuse hair loss may be considered (e.g., illness, medications, trauma) before diagnosing female pattern hair loss. Diagnosis may be slightly more challenging in women than in men, as female pattern hair loss is less defined and tends to consist of broad thinning over large areas of the scalp. A skin biopsy or other procedures (e.g., blood tests) may be used to diagnose medical disorders that can cause balding (e.g., hyperthyroidism, iron deficiency) or that may be confused with female pattern hair loss (e.g., telogen effluvium, alopecia areata).

In most cases, extensive hormonal testing is not needed unless additional signs or symptoms of a hormonal imbalance are present (e.g., hirsutism). In most cases, hairs observed with different degrees of thickness or length are often sufficient to diagnose the disease. An increase in vellus (nonpigmented) hairs may also be noted. Extensive balding for an extended period of time may cause connective tissue (scar tissue) to replace follicles.

Women with female pattern hair loss may be generally classified as having early- or late-onset alopecia, with or without excessive androgen (male sex hormones) levels. These categories may require alternate treatments or result in variable responses to treatment.

The Ludwig classification system may also be used to describe the extent of a patient’s hair loss. However, it is insufficient to diagnose the cause of hair loss. The Ludwig system organizes levels of hair loss in the following manner:

• Grade I. A minimal widening of the part width.
  
• Grade II. Moderate thinning or widening of the part.
  
• Grade III. Extensive thinning and widening of the part width.