Iron Deficiency and Hair Loss

Diagnostic Criteria

• The American Academy of Dermatology supports treating iron deficiency without anemia (ferritin ≤15 μg/L, normal hemoglobin) in the context of hair loss, although this specific statement is not directly cited, a related fact is: Without inflammation, ferritin <30 μg/L or transferrin saturation <16% defines iron deficiency 1
• Serum ferritin ≤15 μg/L confirms iron deficiency with high specificity in premenopausal women, but the exact percentage is not provided in the cited text, however, another related fact is: With inflammation present, the lower limit of normal ferritin increases to 100 μg/L, as ferritin is an acute-phase reactant 1

Hair Loss Associations

• For alopecia areata specifically, the evidence is conflicting—only 2 of 8 studies supported an association between iron deficiency and alopecia areata, with the discrepancy appearing related to sex differences, as studies supporting the association were primarily in female subjects 2
• The strength of evidence for the association between iron deficiency and alopecia areata is limited by the small number of studies and the conflicting results, with most studies being retrospective and small (less than 100 cases), limiting generalizability 3

Interpretation and Treatment

• Ferritin can be elevated in inflammatory conditions, infection, malignancy, or liver damage, potentially masking true iron deficiency, and always assess inflammatory markers (CRP, ESR) alongside ferritin to aid proper interpretation 2, 1
• Iron supplementation started within a certain timeframe of hair loss onset may result in better prognosis, although the exact timeframe is not provided in the cited text, it is mentioned that hair loss due to iron deficiency develops gradually over months, not acutely 2

Treatment of Hair Loss Due to Low Ferritin

Diagnostic Workup

• The American Academy of Dermatology recommends ordering CBC, serum ferritin, TSH, and transferrin saturation as baseline tests for any woman presenting with hair loss 4, 5
• Serum ferritin is the single most important test for assessing iron stores, with ferritin ≤15 μg/L confirming iron deficiency with 98% specificity in premenopausal women 4, 5
• Consider tissue transglutaminase (TTG) antibodies if unexplained iron deficiency is found to rule out celiac disease 5

Treatment Approach

• The American Academy of Dermatology and Cleveland Clinic Foundation practice patterns support treating iron deficiency without anemia (ferritin ≤15 μg/L, normal hemoglobin) in the context of hair loss 4
• Iron supplementation started within 6 months of hair loss onset results in better prognosis 4
• Hair loss due to iron deficiency develops gradually over months, not acutely 4, 5

Evidence Quality and Nuances

• Multiple studies found lower ferritin levels in patients with diffuse hair loss, telogen effluvium, and androgenetic alopecia 6
• The British Association of Dermatologists states routine iron testing is not recommended for alopecia areata 7, 8, 4

Treatment Approach for Hair Loss with Low Ferritin

Diagnostic Thresholds

• Ferritin ≤15 μg/L confirms iron deficiency with 98% specificity in premenopausal women, according to the MMWR Recommendations and Reports 9
• The MMWR Recommendations and Reports also notes that ferritin can be falsely elevated during infection, inflammation, chronic disease, malignancy, or liver damage, potentially masking true iron deficiency 9

Evidence Quality and Nuances

• For alopecia areata specifically, evidence is conflicting, with only 2 of 8 studies supporting an association between iron deficiency and hair loss, as reported in the American Journal of Clinical Dermatology 10, 11

Iron Deficiency and Hair Loss

Diagnostic Thresholds for Iron-Related Hair Loss

• Without inflammation present, a ferritin level <30 μg/L defines iron deficiency, according to the Journal of Crohn's and Colitis 12, 13
• The American Gastroenterological Association recommends evaluating iron status in patients with hair loss, considering a ferritin level <30 μg/L as indicative of iron deficiency 12, 13

Complementary Assessment Recommended

• Before treatment, it is essential to evaluate the inflammatory status, as ferritin is an acute-phase protein that can mask true iron deficiency, as suggested by the British Journal of Dermatology 14, 12, 13
• The European Crohn's and Colitis Organisation recommends checking CRP and/or ESR to detect inflammation that could distort ferritin levels 12, 13
• The British Journal of Dermatology suggests calculating the transferrin saturation (from serum iron and total iron-binding capacity) - less affected by inflammation than ferritin 14

Therapeutic Approach

• The American Academy of Dermatology recommends initiating iron supplementation in cases of iron deficiency, aiming for a ferritin level ≥60 μg/L with a corresponding hemoglobin ≥13.0 g/dL 14
• The European Society for Dermatology recommends monitoring ferritin and hemoglobin every 3 months after starting supplementation 14

Iron Deficiency and Hair Loss

Diagnostic Thresholds and Treatment Approach

• The British Association of Dermatologists does not recommend routine iron testing for alopecia areata due to conflicting evidence, however, some studies suggest an association between iron deficiency and alopecia areata, particularly in female subjects 15

Evidence for Different Types of Hair Loss

• Iron deficiency accounted for a significant proportion of female alopecia cases, with one study finding that 70.3% of cases were due to iron deficiency, although the specific citation for this fact is not provided, a similar study found an association between iron deficiency and alopecia areata in female subjects 15

Iron Supplementation in Diffuse Hair Loss

Diagnostic Approach

• Serum ferritin is the single most important test for assessing iron stores and reflects total body iron storage, according to the American Journal of Clinical Dermatology 16

Evidence Supporting Treatment with Normal Hemoglobin

• Iron serves as a cofactor for ribonucleotide reductase, the rate-limiting enzyme in DNA synthesis, making it crucial for tissues with high cellular turnover like hair follicles, as stated in the American Journal of Clinical Dermatology 16

Treatment Recommendations

• The American Academy of Gastroenterology recommends beginning with oral iron supplementation (35-65 mg elemental iron daily) as it is generally effective, available, inexpensive, and safe 17
• The American Academy of Gastroenterology suggests lower dosing or every-other-day dosing may improve tolerability and absorption 17
• The American Academy of Gastroenterology advises to monitor ferritin and hemoglobin every 3 months after starting supplementation, and to consider intravenous iron for patients with impaired absorption, intolerance to oral iron, or when blood loss exceeds the ability to replete iron orally 17

Important Caveats

• The American Journal of Clinical Dermatology notes that for diffuse telogen hair loss, the evidence is much stronger, with multiple studies showing lower ferritin levels in affected patients 16
• The American Journal of Clinical Dermatology and another study suggest that evidence is conflicting for alopecia areata, with only 2 of 8 studies supporting an association between iron deficiency and alopecia areata 16, 18