Iron deficiency is common in premenopausal women. Evaluation of CBC, serum iron, iron saturation, and ferritin may be warranted. Note that CBC results may be completely normal in women with mild iron deficiency and hair loss. Blood is more essential than hair, and the body will shed hair before red cell indices become microcytic. Also, note that ferritin behaves as an acute phase reactant.
Inflammation can produce normal ferritin levels in an individual who is iron deficient.
Although a low ferritin is proof of iron deficiency, a normal ferritin level does not exclude iron deficiency. Some experts in the field regard iron saturation as the most sensitive indicator of iron deficiency. Occasionally, screening for renal and hepatic enzymes may detect a systemic cause of hair shedding. This process can educate the patient in the normal hair cycle and can confirm the spontaneous resolution of the process. The patient should be instructed to collect all hairs shed in a 24-hour period.