According to the American Society of Hematology, more individuals suffer from iron deficiency than any other micronutrient. Many endure symptoms like fatigue, weakness, and brain fog for extended periods—sometimes even years—before realizing they have a deficiency.
A 2024 study indicates that nearly one-third of adults in the U.S. may be iron deficient. This is concerning, especially since routine screenings done on children and pregnant women—groups at higher risk—might overlook more than 70% of cases.
Some people online are diagnosing themselves, observing dark circles under their eyes and pale skin as signs of low iron. Influencers have even coined the term “ferritin face,” named after the protein that stores iron in the body.
Dr. Ariela Marshall, an associate professor of medicine at the University of Minnesota, emphasizes that iron deficiency is not only common but often unrecognized. New diagnostic guidelines from ASH released in September aim to help more patients receive timely treatment.
The difference between iron deficiency and anemia
When there aren’t enough red blood cells to supply oxygen to the body’s organs and tissues, that’s known as anemia. This condition can lead to symptoms such as tiredness, dizziness, or shortness of breath, along with potential heart palpitations, cold extremities, pale skin, brittle nails, or hair loss.
Anemia is often a result of iron deficiency, which is crucial for brain and muscle health as it helps create hemoglobin—the molecule responsible for oxygen transport in the blood. Iron is stored in ferritin and is required to produce new red blood cells. So, when ferritin levels drop, it indicates insufficient iron for red blood cell production, potentially leading to anemia.
Interestingly, iron deficiency can produce similar symptoms without affecting hemoglobin or red blood cell counts. Affected individuals may also experience restless leg syndrome or even pica—cravings for nonfood items like ice or clay. The reasoning behind these cravings remains somewhat unclear but might suggest the body is trying to absorb iron from its surroundings.
Dr. Marshall points out that it’s a “common misconception” to think that iron deficiency without anemia cannot cause symptoms, which is something that needs to be addressed.
Standard blood tests that measure red blood cell counts typically won’t detect iron deficiency unless it has progressed to anemia.
Dr. Jacquelyn Powers, a section chief in hematology at Texas Children’s Hospital and lead author of the guidelines set for 2026, adds that “the symptoms of iron deficiency can be quite subtle, or they might be mistaken for something else.” Hence, healthcare providers may not always consider checking iron levels.
Measuring the amount of iron in the blood isn’t a solid indicator of deficiency either, as it fluctuates based on recent diet and intake. Ferritin tests are considered the gold standard for determining iron levels, yet there hasn’t been a standard agreed-upon threshold for identifying iron deficiency until now.
The World Health Organization suggests using a ferritin concentration below 15 ng/mL as a marker for diagnosing iron deficiency in school-age children and adults. However, some researchers are questioning this threshold, arguing that setting it too low might miss many individuals with inadequate iron stores.
Interestingly, certain blood-testing labs use even lower thresholds, and as a result, some patients might receive “normal” lab results while actually having low ferritin levels.
The new ASH guidelines establish more appropriate cutoff levels: 20 ng/mL or below for children, 30 ng/mL for most adults, and 50 ng/mL or under for those with heavy menstrual bleeding or other risk factors such as a vegan diet or long-term use of antacids. For adults facing inflammatory conditions, the new limit is 100 ng/mL, and the guidelines recommend an additional test known as transferrin saturation.
One of the key points of the guidelines is to emphasize the importance of testing for iron deficiency, whether or not a patient is anemic. There are practical interventions that could help avoid complications down the line and address subtle symptoms.
People with iron deficiency may report a range of symptoms, from fatigue and tiredness to brain fog or even an urge to chew on things like ice. Marshal notes that individuals can experience all, one, or even none of these symptoms.
While social media posts claim that signs like a pale complexion, hair loss, and dry skin can indicate iron deficiency—labeled as ferritin face—both Powers and Marshall express skepticism about making a diagnosis through images alone.
However, Marshall also mentions that while those with restrictive diets may struggle to meet their iron needs, this isn’t the most common cause of deficiency in the U.S. More prevalent causes include blood loss and various digestive disorders.
Women are generally more prone to iron deficiency due to menstrual blood loss, making those with heavy periods particularly vulnerable.
Children and pregnant individuals are also at a greater risk as their bodies require more iron for growth and development. Interestingly, the occurrence of iron deficiency among pregnant individuals tends to rise with each trimester, according to Powers.
People suffering from chronic gastrointestinal issues like irritable bowel syndrome or Celiac disease may find it challenging to absorb enough dietary iron. Additionally, gastrointestinal blood loss can be an early indication of conditions such as colon cancer.
Endurance athletes have higher iron requirements than most people and thus face an increased risk of deficiency. One telltale sign they might be lacking in iron is simply feeling unable to exercise as intensely as before.
So, if a person leads a healthy lifestyle—eating well, sleeping adequately, and practicing good health habits—but still feels excessively tired, it’s worth checking their ferritin levels. It’s a simple test with straightforward interventions.
Oral iron supplements can often alleviate symptoms within weeks or months. If symptoms improve, it suggests that low iron was indeed a contributing factor. However, it’s crucial to collaborate with a doctor to understand the underlying reasons for low iron levels, according to Marshall.
