Most Common Cause of Hair Loss in Women
Androgenetic alopecia (female pattern hair loss) is the most common cause of hair loss in women, affecting approximately 50% of women over their lifetime and up to 40% of healthy women by reproductive age. 1, 2
Understanding Androgenetic Alopecia
Androgenetic alopecia is caused by androgens in genetically susceptible women, with dihydrotestosterone (DHT) binding to androgen receptors in hair follicles, causing progressive miniaturization of terminal follicles. 3 The condition typically presents with:
- Diffuse thinning over the mid-frontal and parietal scalp with preservation of the frontal hairline 3, 4
- Retention of occipital scalp density 3
- Presence of miniaturized hairs within follicular units 4
- Onset typically between ages 12-40 years with polygenic inheritance 3
The key pathophysiologic difference in women compared to men is that women have significantly higher levels of cytochrome p-450 aromatase in frontal follicles, which partially protects against complete baldness—explaining why women develop diffuse thinning rather than complete baldness until very late stages. 3
Other Important Causes to Consider
While androgenetic alopecia is most common, several other conditions frequently cause hair loss in women:
Telogen Effluvium
- Stress-induced shedding triggered by physiologic or emotional stressors (illness, surgery, childbirth, rapid weight loss) 5
- Characterized by diffuse shedding without the miniaturization pattern seen in androgenetic alopecia 5
Alopecia Areata
- Autoimmune condition causing patchy, non-scarring hair loss with characteristic exclamation mark hairs 5, 6
- Associated with other autoimmune diseases in 20% of cases 5
- 34-50% recover spontaneously within one year 5
Nutritional Deficiencies
- Iron deficiency (low ferritin) is the most common nutritional deficiency worldwide causing chronic diffuse telogen hair loss 5
- Vitamin D deficiency (<20 ng/mL) affects 70% of alopecia areata patients versus 25% of controls 5
- Zinc deficiency impairs hair follicle function 5, 6
Diagnostic Approach
Most women with androgenetic alopecia have normal menses and pregnancies, and extensive hormonal testing is unnecessary unless signs of androgen excess are present. 3 The American Academy of Family Physicians recommends targeted testing only when specific clinical features suggest underlying pathology:
When to Order Laboratory Tests
- Test for testosterone, SHBG, and consider PCOS evaluation only if signs of androgen excess exist (hirsutism, severe acne, irregular periods) 5
- Check TSH to rule out thyroid disease 5, 6
- Measure serum ferritin, vitamin D, and zinc levels to identify nutritional deficiencies 5, 6
- Consider prolactin if hyperprolactinemia suspected 5
Clinical Diagnosis Features
- Early age of onset with frontal/parietal thinning pattern and occipital preservation strongly suggests androgenetic alopecia 3
- Dermoscopy can differentiate androgenetic alopecia from alopecia areata (which shows yellow dots and exclamation mark hairs) and telogen effluvium 5
Common Pitfalls to Avoid
Avoid ordering excessive laboratory tests when the clinical diagnosis of androgenetic alopecia is evident based on pattern and age of onset. 5 The diagnosis is primarily clinical in most cases. 3
Do not overlook the psychological impact—hair loss causes significant stress and reduced quality of life in women, who typically do not anticipate age-related hair loss unlike men. 4, 2 Assessment for anxiety and depression may be warranted. 5
Remember that baldness in women occurs only when all hairs within follicular units are miniaturized, which is a relatively late event—early intervention with treatment is most effective. 4
Treatment Considerations
Topical minoxidil is the only FDA-approved medication for promoting hair growth in women with androgenetic alopecia, with efficacy demonstrated in double-blind studies. 3 Other options include: