Is There Really No Clear Association Between Low Serum Ferritin and Chronic Diffuse Telogen Hair Loss?

The document discussed the debate over the association between low serum ferritin levels and chronic diffuse telogen hair loss. Dr. Sinclair's study concluded there was no clear link, based on the assumption that a serum ferritin level of >20 µg/L indicated adequate iron stores. However, this position was challenged, suggesting that the 'normal' ranges for serum ferritin and hemoglobin were derived from populations with a high proportion of iron-deficient women. Supporting this, a large-scale study of 12,828 participants by Waalen et al. found 38% of San Diego women were iron deficient, indicating that reference ranges might have normalized abnormal iron levels.