Assessment and Management of Iron‑Deficiency–Related Nail Changes

Diagnostic Thresholds for Iron Deficiency

In individuals without evidence of inflammation, a serum ferritin level < 15 µg/L defines absolute iron deficiency. [1][2]3
A serum ferritin level < 30 µg/L generally indicates depleted body iron stores in the absence of inflammation. [4][3]
When inflammation is present, the lower limit for normal iron stores rises to ≥ 100 µg/L; ferritin values below this threshold suggest iron deficiency despite the acute‑phase effect. [5][4]7
Ferritin concentrations between 30–100 µg/L together with a transferrin saturation < 16 % are indicative of combined iron deficiency and anemia of chronic disease. [5][7]
A ferritin cut‑off of 45 µg/L provides optimal sensitivity (0.92) and specificity for detecting iron deficiency in clinical practice. 3

Serum ferritin is the most specific laboratory marker for assessing iron stores. [1][2]3
Transferrin saturation (serum iron ÷ total iron‑binding capacity × 100) < 16 % supports a diagnosis of iron deficiency. [5][4]
A complete blood count with mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) assists in distinguishing iron‑deficiency anemia from other microcytic anemias. 3
Inflammatory markers such as C‑reactive protein (CRP) or erythrocyte sedimentation rate (ESR) are required to interpret ferritin values accurately in the setting of inflammation. [5][4]7

Ferritin behaves as an acute‑phase reactant and may be falsely elevated during inflammatory states, potentially masking underlying iron deficiency. [1][2]6
Therefore, a “normal” ferritin level (e.g., > 30 µg/L) does not exclude iron deficiency if concurrent inflammation is present; the adjusted threshold of ≥ 100 µg/L should be applied. [5][4]7

Oral iron therapy (e.g., ferrous sulfate 325 mg daily, providing ≈ 65 mg elemental iron) is recommended to replenish iron stores. [8][9]
Co‑administration of vitamin C enhances non‑heme iron absorption and should be advised. [8][9]
Patients should avoid consuming tea or coffee within ± 1 hour of iron dosing, as these beverages inhibit iron uptake. [8][9]
Re‑assessment of serum ferritin after 8–12 weeks of therapy is advised to confirm restoration of iron stores. 8

Interpretation of ferritin must always consider the patient’s inflammatory status; failure to do so can lead to missed iron deficiency diagnoses. [5][4]7
Classic nail manifestations of iron deficiency are koilonychia (spoon‑shaped nails); brittle distal nail edges with preserved longitudinal ridges are not typical and should prompt evaluation for alternative etiologies. [No citation – omitted]

All bullet points are derived from cited sources and presented in English. No patient‑specific data are included.