"Iron Deficiency Without Anemia – Common, Important, Neglected Esa Soppi Depatrment of Internal medicine, Eira Hospital, Laivurinkatu 29, FI-00150 Helsinki, Finland DOI: 10.15761/CCRR.1000456 Article Article Info Author Info Figures & Data Abstract A serum ferritin concentration of <30 µg/L is the most sensitive and specific test for the identification of iron deficiency in patients with or without anemia. However, patients may be iron deficient at much higher concentrations of ferritin. Iron deficiency without anemia and with normal red blood count is a clinical challenge, and many patients have been diagnosed with a multitude of conditions ranging from hypothyroidism to depression to chronic fatigue syndrome over the years when they have sought help for their often debilitating symptoms. The key to a correct diagnosis are assessment of the serum ferritin concentration and a meticulous medical history focusing on the possibility of life-long blood losses and diseases such as celiac disease. Differential diagnostic causes for the symptoms must be sought for. The mainstay of therapy is oral iron in sufficient doses for at least 6 to 9 moths together with serum ferritin monitoring. Some patients who do not respond to oral iron treatment may need intravenous iron. The longer the iron deficiency has lasted, the more challenging the therapy may be. Some iron deficient patients without anemia may have had the condition for over a decade, and may not fully recover. The amount of human suffering, the loss of quality of life and the indirect costs to society caused by iron deficiency are huge....... During my 30-year carrier as a consulting internist I have met hundreds of patients, mainly menstruating females, who have sought medical advice for prolonged (1–35 years) fatigue, brain fog, muscle and joint pains, weight gain, headache, dyspnea, palpitations (sometimes associated with sleep disturbances), arrhythmia, lump in the throat or difficulty in swallowing or restless legs. Over time, the patients have often received a spectrum of diagnoses and corresponding treatments: subclinical hypothyroidism, fibromyalgia, burnout, overtraining, asthma, somber mood extending from melancholy to severe therapy-resistant depression, chronic fatigue syndrome and chronic Lyme disease. It is important to include iron deficiency without anemia as a differential diagnostic possibility, because this type of iron deficiency is very often associated with symptoms that severely impair the patient’s performance and quality of life and may even hinder the patient from overcoming the ordinary challenges of everyday life and may cause permanent disability." (my bolding) https://www.oatext.com/iron-deficiency-without-anemia-common-important-neglected.php This 2019 article is I think relevant to some with ME, who may also suffer from iron deficiency without anemia. As well as those with anemia. I believe that just as iron deficiency without anemia can masquerade as ME, so can ME mask iron deficiency without anemia. Several of the symptoms are similar, and this iron deficiency can go unsuspected by both patients and physicians. It's my understanding the go-to lab test for fatigue/anemic type symptoms does not include measuring the ferritin level. Something that the author of this article emphasizes as very important. Once missed, this iron deficiency is passed by, and other reasons may be sought for these symptoms, which may lead to further misdiagnoses. Thank you for your comments.