Differential Diagnosis for Significant Hair Loss

• Single most likely diagnosis
  • Androgenetic alopecia: This is the most common cause of hair loss in both men and women, characterized by a gradual thinning of hair due to the conversion of testosterone to dihydrotestosterone (DHT), which affects hair follicles.
• Other Likely diagnoses
  • Alopecia areata: An autoimmune condition that leads to patchy hair loss, often on the scalp, but can also affect other areas of the body.
  • Telogen effluvium: A condition that causes excessive hair shedding due to a disruption in the normal hair growth cycle, often triggered by stress, hormonal changes, or certain medications.
  • Tinea capitis (ringworm of the scalp): A fungal infection that can cause hair loss, typically accompanied by itching, redness, and scaling on the scalp.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Thyroid disorders (hypo- or hyperthyroidism): Both underactive and overactive thyroid glands can lead to hair loss, among other symptoms, and require prompt treatment to prevent long-term complications.
  • Lupus: A chronic autoimmune disease that can cause hair loss, along with a variety of other symptoms including skin rashes, joint pain, and kidney problems.
  • Syphilis: A sexually transmitted infection that can cause hair loss in its secondary stage, along with other symptoms like rash, fever, and swollen lymph nodes.
• Rare diagnoses
  • Trichotillomania: A psychological disorder characterized by an irresistible urge to pull out one's own hair, leading to noticeable hair loss.
  • Lichen planopilaris: A rare inflammatory condition that causes hair loss, typically on the scalp, due to inflammation and scarring of hair follicles.
  • Frontal fibrosing alopecia: A condition that causes hair loss and scarring on the scalp, particularly affecting the frontal area, often accompanied by eyebrow loss.