If your doctor tells you your iron is normal, ask for the test results. There are two iron blood tests: hemoglobin and ferritin. For hemoglobin, the test range suggested as normal by your doctor is 117–160 g/L for women. Yet we know that a hemoglobin below 140 g/L will cause significant hair loss. Ferritin, which is your iron storage, has a suggested test range of 15–160 ug/L; but to prevent hair loss and ensure thick hair, your reading should be above 40 ug/L.