Many patients with fatigue as a main complaint are eventually diagnosed as having an endocrine problem. However, an often overlooked reason for fatigue in women who are menstruating is iron deficiency. Iron is needed for thyroid hormone biosynthesis, including the conversion from the inactive thyroid hormone, T4, to the active hormone, T3. Women taking thyroid hormone are especially likely to benefit from treating iron deficiency. Men are unlikely to be iron deficient, as the
main reason for low iron in younger patients is loss through menses.
That severe iron deficiency leads to anemia, as manifested by low hemoglobin and hematocrit on a CBC blood test is well-known. However, mild iron-deficiency leads to low ferritin in blood tests BEFORE a drop in hemoglobin and hematocrit occurs. An article published in the May 2003 British Medical Journal showed that patients with low ferritin, but normal hemoglobin and hematocrit, have fatigue that is reversed by iron treatment. Since Dr. Friedman’s goal is early diagnosis of treatable diseases, he recommends measuring a ferritin level in all women who have fatigue. Performing a CBC is not needed.
Colon cancer can also give a low ferritin level, but it is unlikely in younger females whose main complaint is fatigue and who do not have weight loss. In men or older women, a low ferritin may warrant a colon cancer work-up, depending on evaluation by the patient’s primary doctor.
The normal range for ferritin is usually between 30 and 300 mg/dL, but Dr. Friedman recommends iron treatment for everyone with a ferritin less than 60 mg/dL. The goal of treatment is to raise ferritin levels to a value between 70 and 90 mg/dL and is usually achieved with oral iron treatment. Raising ferritin levels to this range may be needed for patients with hypothyroidism to have an optimal response to thyroid hormone treatment. Dr. Friedman’s philosophy is proper ferritin levels are crucial for good hormone health, and he advocates attempting to raise them fairly rapidly.
Ferrous sulfate (325 mg orally, available over the counter) has usually been the recommended treatment; however, this preparation is often poorly tolerated.