What are the most common causes of female hair loss?

Most Common Causes of Female Hair Loss

The most common causes of female hair loss include androgenetic alopecia, telogen effluvium, alopecia areata, nutritional deficiencies (particularly iron and vitamin D), hormonal imbalances, and stress-related factors. 1

Primary Types of Female Hair Loss

1. Androgenetic Alopecia (Female Pattern Hair Loss)

• Most prevalent form affecting over 50% of postmenopausal women and up to 40% of women of reproductive age 2
• Characterized by:
  • Diffuse thinning in the parietal or frontovertical areas with intact frontal hairline
  • Progressive miniaturization of hair follicles
  • Can be with or without excess androgens 3
• Diagnosis involves:
  • Clinical pattern recognition
  • Trichoscopy showing hair shaft diameter variation
  • Laboratory testing for hormonal abnormalities in some cases

2. Telogen Effluvium

• Common trigger-induced diffuse hair shedding
• Key triggers include: 1
  • Childbirth
  • Major surgery or severe illness
  • Sudden weight loss
  • Emotional stress
  • Iron deficiency
  • Thyroid disorders
  • Nutritional deficiencies
  • Certain medications (retinoids, antifungal agents, hormonal therapies)

3. Alopecia Areata

• Autoimmune condition causing patchy hair loss
• Often associated with:
  • Lower vitamin D levels 4
  • Possible genetic predisposition
  • Other autoimmune conditions

Nutritional and Hormonal Factors

Nutritional Deficiencies

• Iron deficiency: Most common nutritional deficiency associated with chronic diffuse telogen hair loss 4

  • Iron serves as a cofactor for ribonucleotide reductase, important for DNA synthesis in hair follicle matrix
  • Studies show mixed results but suggest stronger association in female patients 4

• Vitamin D deficiency: 4, 1

  • Multiple studies show lower serum 25(OH)D levels in alopecia patients
  • Vitamin D has established roles in normal hair follicle function
  • Vitamin D receptor (VDR) activity is greatest during the anagen (growth) phase

Hormonal Factors

• Androgens play a central role: 5
  • Dihydrotestosterone (DHT)
  • Testosterone
  • Androstenedione
  • Dehydroepiandrosterone (DHEA) and its sulfate (DHEAS)
• Estrogen deficiency (naturally occurring during menopause) 5
• Thyroid dysfunction (both hypothyroidism and hyperthyroidism) 5, 1
• Hypothalamic-pituitary-adrenal axis dysregulation (stress hormones) 5

Diagnostic Approach

When evaluating female hair loss, a systematic approach is recommended: 1, 6

1. Pattern assessment:

   • Diffuse thinning (telogen effluvium, nutritional deficiencies)
   • Patterned loss (androgenetic alopecia)
   • Focal patches (alopecia areata)

2. Laboratory testing:

   • Complete blood count
   • Ferritin levels (optimal >50 ng/mL for hair growth)
   • Thyroid stimulating hormone
   • Vitamin D 25OH levels
   • Hormonal panel when androgenic alopecia is suspected

3. Specialized tests:

   • Trichoscopy/dermoscopy
   • Hair pull test
   • Scalp biopsy (when scarring alopecia is suspected)

Clinical Pearls and Pitfalls

• Underrecognized impact: Hair loss significantly affects psychological well-being and quality of life, with increased rates of anxiety and depression 6
• Diagnostic challenges: Multiple causes often coexist (e.g., androgenetic alopecia with concurrent iron deficiency)
• Treatment expectations: Set realistic goals and timelines; most treatments require 3-6 months before visible improvement
• Avoid excessive supplementation: Particularly with biotin, which can interfere with laboratory testing 2
• Consider racial/ethnic variations: Central centrifugal cicatricial alopecia is more common in women of African descent 6

By understanding these common causes and implementing appropriate diagnostic strategies, clinicians can better address female hair loss and improve patient outcomes.