Studies showed that HbH disease had lower MCV (61 (58.8–65.6) fl) and ferritin (203 (99–279) μg/L) values and higher hepcidin (2.4 (1.4–4.1) nM) compared with β-thalassemia intermedia MCV (80 (73.0–87.5) fl), ferritin (471 (298–589) μg/L) and hepcidin (0.25 (0.25–0.25) nM), respectively [45]. This evidence concerns the gene HAMP and hemoglobin H disease.