Cotsarelis and Trost say that what most doctors consider to be a normal ferritin level is, in fact, too low. Ferritin levels of 10-15 ng/mL are within the "normal" range. Cotsarelis says a ferritin level of at least 50 ng/mL is needed to help replenish hair. Trost and Bergfeld shoot for 70 ng/mL.
"Doctors see ferritin levels in the normal range, and don't do anything," Cotsarelis says. "But the normal range is wrong, I think. The normal range for women is 10-120 ng/ML, and for men it is 30-250 ng/mL. Why should a man's be lower than a woman's? Mostly because women are iron deficient. It is almost a public health problem. Hair loss is only an indication of this."
Cotsarelis and colleagues have found that women with hair loss have significantly lower iron stores than women without hair loss. Surprisingly, this was particularly true for women with alopecia areata, a form of hair loss caused by haywire immune responses.
"Our theory is that lower iron levels decrease the threshold for developing hair loss of any kind in genetically predisposed individuals," Cotsarelis says. "So people prone to develop even hereditary hair loss, if their iron levels are low, it accelerates that process. We think it's because the hair follicles grow so much, they require a lot of iron."
Women who frequently have heavy menstrual periods often become iron deficient. "If you have a healthy woman with hair loss, you can assume iron deficiency," Trost says.
Iron deficiency is less common in men and postmenopausal women than in women of childbearing age. But it's something Cotsarelis and Trost see often in people with hair loss. Especially when it gets to the point of anemia, iron deficiency can be a symptom of very serious illness. It's important for a doctor to find out why this is happening.
"If you have a man or a postmenopausal woman with iron-deficiency anemia, you need to do a workup to find out why," Trost says. "Say you have a 55-year-old man with iron-deficiency anemia -- it could be caused by bleeding due to coloncancer. Believe it or not, someone can come in complaining of hair loss, and find out it is something serious."