To determine if a woman has low serum ferritin levels, a blood
test is performed. (It is important to note that hemoglobin is the standard measure for iron in the blood, and while hemoglobin levels can diagnose anemia, they do not always correspond with low serum ferritin hair loss. A woman can have plenty of hemoglobin, yet still suffer from low serum ferritin levels.)
When it comes to ferritin levels and female hair, ferritin levels are simply more important to the body.