There is no clear association between low serum ferritin and chronic diffuse telogen hair loss

In a study from 1997 to 1999 with 194 women suffering from chronic diffuse telogen hair loss, researchers found no clear link between hair loss and low serum ferritin levels (≤ 20 µg L−¹). Only 6.2% of the participants had such low ferritin levels, and even with iron supplementation that increased ferritin levels above the threshold, there was no improvement in hair loss among those with low iron stores and normal scalp histology. The study concluded that low serum ferritin does not directly cause hair loss, and that iron supplementation may not be an effective treatment for this condition. It also suggested that other causes of hair loss should be considered before attributing it to low iron stores.