Why are ferritin and zinc levels checked in patients with vitiligo?

Why Ferritin and Zinc Levels Are Checked in Vitiligo

Ferritin and zinc levels are checked in vitiligo patients primarily to screen for associated autoimmune conditions and nutritional deficiencies that may contribute to disease activity, rather than as part of routine diagnostic workup recommended by major guidelines.

Guideline-Based Screening Recommendations

The British Association of Dermatologists' vitiligo guidelines focus primarily on thyroid screening rather than routine ferritin or zinc testing:

• Thyroid function testing is the main recommended screening in adults with vitiligo, given that 34% have autoimmune thyroid disease 1
• The guidelines do not specifically recommend routine ferritin or zinc testing as part of standard vitiligo evaluation 1

Rationale for Ferritin Testing in Vitiligo

While not specifically addressed in vitiligo guidelines, ferritin testing may be considered based on several factors:

Association with Autoimmune Conditions

• Iron deficiency is found in approximately 19.7% of vitiligo patients, with 12% having low iron levels and 9.9% having anemia 2
• Since vitiligo is an autoimmune condition with high rates of other autoimmune diseases (40.3% of patients), screening for iron deficiency may identify concurrent autoimmune gastritis or celiac disease 2

Clinical Context from Related Guidelines

• The British Association of Dermatologists recommends ferritin testing for chronic pruritus without rash, as iron deficiency can cause dermatologic symptoms 1
• Ferritin is an acute-phase protein and may be falsely elevated during inflammation, so interpretation requires clinical context 1, 3

Rationale for Zinc Testing in Vitiligo

Zinc testing is based on research evidence rather than guideline recommendations:

Research Findings on Zinc Deficiency

• Serum zinc levels are significantly lower in vitiligo patients (80.11 ±17.10 μg/dl) compared to healthy controls (96.10 ±16.16 μg/dl, p = 0.0001) 4
• Zinc levels show significant negative correlation with inflammatory cytokines (IL-4, IL-6, IL-17) that are elevated in vitiligo 5
• Zinc decreases significantly after narrow-band UVB phototherapy, suggesting increased utilization during treatment 6

Mechanistic Rationale

• Zinc functions as an antiapoptotic factor and cofactor for antioxidant defense systems, both of which may be impaired in vitiligo pathogenesis 7
• Zinc plays an important role in melanogenesis, the process of melanin production that is disrupted in vitiligo 7

Important Clinical Caveats

Testing Interpretation

• If ferritin appears normal but microcytic anemia is present, check serum iron and total iron binding capacity to confirm true iron status 1, 3
• Consider tissue transglutaminase (TTG) antibodies if unexplained iron deficiency is found to rule out celiac disease 1, 3

Limitations of Current Evidence

• No high-quality guidelines specifically recommend routine zinc or ferritin testing in vitiligo 1
• The evidence for zinc supplementation improving vitiligo outcomes requires further large-scale studies 4, 5
• Testing may be most appropriate when clinical suspicion exists for nutritional deficiency or when patients have treatment-resistant disease 2

Practical Approach

• Prioritize thyroid function testing first as this has the strongest guideline support in vitiligo 1
• Consider ferritin and zinc testing in patients with: extensive disease, poor treatment response, symptoms suggesting nutritional deficiency, or other autoimmune conditions 2
• If ferritin is below 15-25 μg/L or zinc is significantly reduced, consider supplementation while investigating underlying causes 1, 4