What are the possible causes of hair loss in an unmarried, non‑pregnant woman?

Causes of Hair Loss in Unmarried, Non-Pregnant Women

Hair loss in unmarried, non-pregnant women is most commonly due to female pattern hair loss (FPHL), followed by chronic telogen effluvium, nutritional deficiencies, thyroid disorders, and autoimmune conditions like alopecia areata. 1

Primary Categories of Hair Loss

1. Female Pattern Hair Loss (FPHL) - Most Common

FPHL is the predominant cause of hair loss in women and presents with:

• Central scalp thinning with preservation of the frontal hairline 1
• Hair follicle miniaturization (variety of hair diameters and lengths in affected areas)
• Preserved follicular ostia (no scarring)
• No diffuse shedding across the entire scalp 1

Important distinction: Despite its name, FPHL is NOT always androgen-related. Most affected women have normal circulating androgen levels and no other signs of hyperandrogenism 1. The condition has even been reported in women with complete androgen deficiency or absent androgen receptors 1.

2. Chronic Telogen Effluvium (CTE)

This presents differently from FPHL:

• Diffuse scalp hair thinning affecting the entire scalp, not just central areas
• Persistent generalized shedding
• Positive hair pull test from multiple scalp areas, including the occiput
• Often triggered by stress, medications, or systemic illness 2
• Terminal-to-vellus hair ratio remains normal (9:1), indicating lack of miniaturization 1

3. Alopecia Areata

An autoimmune condition characterized by:

• Patchy hair loss with completely smooth skin in affected areas
• Exclamation mark hairs at margins of expanding patches
• Yellow dots visible on dermoscopy
• About 20% have family history 3
• 80% spontaneous remission within 1 year for limited patches, but only 10% recovery for extensive disease 3

4. Endocrine Disorders

Thyroid dysfunction: Hypothyroidism can cause telogen effluvium and impair hair regrowth in FPHL. Screen thyroid function in all women with hair loss 1.

Polycystic Ovary Syndrome (PCOS): Meta-analysis shows 28% of PCOS patients have FPHL 1. Look for irregular periods, hirsutism, acne, and metabolic abnormalities.

Hyperprolactinemia: Found in 7.2% of FPHL patients in one series, with 1.8% having prolactinomas 1. Can be secondary to hypothyroidism.

5. Nutritional Deficiencies

The evidence here is mixed but warrants evaluation:

Iron deficiency:

• Found in 29% of FPHL patients in one study 1
• However, a larger controlled study showed no significant increase in iron deficiency in FPHL patients versus controls 1
• Critical caveat: Iron supplementation in patients with low-normal ferritin (<70 mg/L) did NOT improve hair loss 1
• Despite weak evidence, check ferritin given the ease of testing

Vitamin D deficiency:

• 62% of FPHL patients had low 25-hydroxyvitamin D levels 1
• Causal relationship unproven but worth screening

Zinc deficiency:

• 15% of FPHL patients had low zinc levels 1
• Mean zinc levels lower in FPHL patients versus controls 1

Biotin: Avoid excessive supplementation as it interferes with diagnostic tests 4

6. Other Scarring Alopecias

Central Centrifugal Cicatricial Alopecia (CCCA):

• Primarily affects African American women
• Central/frontal/vertex hair loss progressing to frank baldness
• Loss of follicular ostia (scarring)
• May be triggered by hair care practices (hot combs, relaxers) in women with underlying FPHL 1

Frontal Fibrosing Alopecia (FFA):

• Receding hairline with perifollicular erythema
• Eyebrow loss
• Primarily postmenopausal white women
• Requires scalp biopsy showing lymphocytic infiltrate 1

Recommended Diagnostic Approach

Based on the 2019 Androgen Excess and PCOS Committee guidelines 1:

Initial Clinical Assessment:

1. Pattern of hair loss: Central (FPHL) vs. diffuse (CTE) vs. patchy (alopecia areata)
2. Hair pull test: Multiple scalp areas including occiput
3. Scalp examination: Check for follicular ostia preservation, inflammation, scarring
4. Dermoscopy: Look for hair diameter variation, yellow dots, perifollicular changes

Laboratory Evaluation:

Mandatory tests (Level of Evidence C) 1:

• Androgens: Total testosterone (LC/MS preferred), free testosterone, SHBG
• Thyroid profile: TSH, free T4
• Prolactin
• Iron studies: Ferritin, serum iron, TIBC
• Vitamin D: 25-hydroxyvitamin D
• Zinc level

When to Biopsy:

• Diagnosis uncertain after clinical examination
• Suspicion of scarring alopecia
• Need to differentiate FPHL from CTE (terminal-to-vellus ratio: <1.7:1 in FPHL vs. 9:1 in CTE) 1

Common Pitfalls to Avoid

1. Assuming all hair loss is androgenetic: Most women with FPHL have normal androgen levels 1

2. Over-supplementing iron: Iron supplementation doesn't improve FPHL even with low-normal ferritin 1

3. Missing scarring alopecias: Always check for follicular ostia preservation. Once scarring occurs, hair follicles are permanently lost 1

4. Ignoring psychological impact: Hair loss severely affects quality of life, anxiety, depression, and work productivity 2. Address mental health alongside physical treatment.

5. Confusing FPHL with CTE: FPHL has central pattern with miniaturization; CTE has diffuse shedding with positive hair pulls throughout scalp including occiput 1

6. Not screening for autoimmune diseases: While routine screening isn't recommended for all alopecia areata patients 3, consider it when clinical suspicion exists

Age-Related Considerations

• Reproductive age women: Consider PCOS, nutritional deficiencies (especially iron in premenopausal women), stress-related telogen effluvium
• Perimenopausal/postmenopausal: FPHL becomes more common, affecting over 50% of postmenopausal women 4; also increased risk of frontal fibrosing alopecia 5