What are the common causes of alopecia in a 70-year-old woman?

Causes of Alopecia in 70-Year-Old Women

Androgenetic alopecia (female pattern hair loss) is the most common cause of hair loss in 70-year-old women, affecting up to 50% of women during their lifetime, followed by nutritional deficiencies (particularly iron deficiency), telogen effluvium, alopecia areata, and thyroid disease. 1, 2

Most Common Causes in This Age Group

Androgenetic Alopecia (Female Pattern Hair Loss)

• This is the single most common cause, affecting up to 50% of women over their lifetime 2
• Presents as diffuse thinning of the crown region with maintenance of the frontal hairline (Ludwig pattern) 2
• Results from effects of dihydrotestosterone (DHT) on androgen-sensitive hair follicles 2
• Diagnosis is primarily clinical, with dermoscopy showing hair diameter diversity and miniaturization 2

Nutritional Deficiencies

• Iron deficiency accounts for 70.3% of female alopecia cases in recent studies and is the most common nutritional deficiency worldwide 3
• Serum ferritin <60 ng/mL is associated with hair loss, even when hemoglobin levels appear normal 3
• The adequate ferritin level for hair growth is 40-60 ng/mL, corresponding to hemoglobin ≥13.0 g/dL 3
• Vitamin D deficiency shows 70% prevalence in alopecia patients versus 25% in controls, with inverse correlation to disease severity 4
• Zinc deficiency is associated with lower serum levels in alopecia patients 4

Telogen Effluvium

• Common cause of diffuse hair shedding triggered by physiological stress, illness, or medications 1
• Often self-limited but requires identification of underlying trigger 1
• Can be acute or chronic in nature 5

Alopecia Areata

• Autoimmune condition mediated by T lymphocytes targeting hair follicles 6, 4
• Presents as patchy, non-scarring hair loss with exclamation mark hairs at margins 6
• About 20% have family history of the disease 6, 4
• Associated with other autoimmune diseases including thyroid disease and vitiligo 7

Thyroid Disease

• Both hypothyroidism and hyperthyroidism can cause diffuse hair loss 4
• TSH screening is essential to rule out thyroid dysfunction 4
• Thyroid peroxidase (TPO) antibody testing warranted if biochemical hypothyroidism confirmed 4

Less Common but Important Causes

Scarring Alopecias

• Frontal fibrosing alopecia, lichen planopilaris, and discoid lupus erythematosus 8
• These permanently destroy hair follicles and require prompt diagnosis 8
• Scalp shows signs of inflammation, scarring, or loss of follicular openings 9

Medication-Induced Hair Loss

• Anagen effluvium from chemotherapy or systemic treatments 6, 7
• Various medications can trigger telogen effluvium 7

Systemic Conditions

• Systemic lupus erythematosus can present with patchy hair loss 6, 7
• Secondary syphilis should be considered in appropriate clinical context 6, 7

Diagnostic Approach

Clinical Examination

• Determine if hair loss is scarring versus non-scarring, as this fundamentally directs all subsequent decisions 9
• Look for exclamation mark hairs (indicate active alopecia areata) 6, 9
• Assess for scalp inflammation, scaling, or follicular destruction 9
• Perform hair pull test to assess active shedding 7

Dermoscopy

• Regular round yellow dots commonly seen in alopecia areata 6
• Hair diameter diversity and miniaturization in androgenetic alopecia 2
• Helps differentiate between conditions like trichotillomania and alopecia areata 6

Laboratory Testing (When Indicated)

• Serum ferritin is the single most important nutritional test, with target level ≥60 ng/mL for adequate hair growth 3
• TSH to exclude thyroid disease 4
• Vitamin D level (deficiency defined as <20 ng/mL or <50 nmol/L) 4
• Serum zinc level 4
• Complete blood count to assess for anemia 3
• Consider fungal culture if tinea capitis suspected 6, 4
• Skin biopsy for difficult cases, early scarring alopecia, or when diagnosis uncertain 6, 4

Critical Pitfalls to Avoid

• Do not assume all hair loss in older women is androgenetic alopecia without excluding nutritional deficiencies, particularly iron deficiency 3
• Do not order extensive laboratory panels when clinical diagnosis is evident 9
• Do not overlook the psychological burden—assess mental health impact and provide support resources 9
• Do not miss scarring alopecia, as delayed diagnosis leads to permanent hair loss 8
• Initiation of iron supplementation within 6 months results in better prognosis for iron deficiency-related alopecia 3
• Do not confuse trichotillomania with alopecia areata—broken hairs in trichotillomania remain firmly anchored unlike exclamation mark hairs 9