Always tired? How to know if you are iron deficient

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More people are low in iron than in any other micronutrient, according to the American Society of Hematology. But many live with fatigue, weakness, brain fog and other symptoms for months or years before a deficiency is caught.

Nearly one-third of adults in the United States may be iron deficient, according to a 2024 study. And routine screening among children and pregnant women — who are at high risk — may miss more than 70% of cases .

Some people online are self-diagnosing, citing dark under-eye circles and pale skin as evidence that they are low in iron. Social media influencers call the look “ ferritin face ,” named after a protein that stores the element in the body.

Iron deficiency is common, prevalent and underrecognized , said Dr. Ariela Marshall, associate professor of medicine at the University of Minnesota. New diagnostic recommendations, which ASH released in September, aim to ensure more patients secure early treatment.

Anemia is a condition that occurs when there are not enough red blood cells to carry oxygen to the body’s organs and tissues. Patients with anemia may feel tired, dizzy or short of breath, and they may have heart palpitations, cold hands and feet, pale skin, brittle nails or hair loss.

Anemia is often caused by a lack of iron, which supports brain and muscle function and is used to make hemoglobin, the molecule that transports oxygen in the blood. Stored in the protein ferritin, iron is recruited to make the hemoglobin in new red blood cells. When ferritin is low, it means there isn’t enough iron available to make red blood cells, which can lead to anemia.

But iron deficiency can cause the same sorts of symptoms without affecting hemoglobin or red blood counts. Having low iron can also cause restless leg syndrome and pica — cravings for nonfood items such as ice or clay. (Doctors are not sure why; it may be a sign that the body is seeking out iron from the environment.)

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If you’re constantly tired, these health conditions could be the reasons why, experts say

It is “a common misperception” that iron deficiency without anemia can’t cause symptoms, “and one that we definitely need to correct,” Marshall said.

Standard blood tests that count how many red blood cells a person has won’t catch iron deficiency that has not progressed into anemia.

“The symptoms of iron deficiency can be very subtle, or they can be attributed to many different things,” said Dr. Jacquelyn Powers, section chief of hematology at Texas Children’s Hospital and lead author of the 2026 guidelines. “Providers are not always thinking, ‘Oh, I need to check iron labs.’”

The amount of iron in a person’s blood cannot provide an accurate diagnosis of deficiency because it will vary depending on what they have eaten and how recently. Ferritin tests are the gold standard for assessing iron levels, Powers said. But until now, there has not been a single agreed-upon results threshold to determine who has iron deficiency.

The World Health Organization recommends using a ferritin concentration below 15 ng/mL for diagnosing school-age children and adults with iron deficiency. But researchers have questioned that math , expressing concern that such a low threshold misses many people whose iron stores are higher than that but still insufficient.

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Some blood-testing laboratories use even lower cutoffs, meaning some patients’ lab tests may come back as “normal” even if their ferritin levels are very low.

The new ASH guidelines establish 20 ng/mL or less as the appropriate cutoff for children, 30 ng/mL for most adults, and 50 ng/mL or less for those with heavy menstrual bleeding or other risk factors such as a vegan diet or long-term antacid use for reflux. For adults with inflammatory issues, the new limit is 100 ng/mL, and the group suggests an additional test, called transferrin saturation.

“One of the goals of the guidelines was to highlight why testing for iron deficiency — regardless of whether the patient is anemic or not — is important because there are interventions that you can do to prevent later complications and address more subtle symptoms,” Powers said.

People with iron deficiency may have “a whole range of symptoms, from tiredness and fatigue to brain fog or cloudy thinking to feeling like you want to chew on things like ice,” Marshall said. “Somebody can have all of those. They can have one of them. They can have none of them.”

Social media posts claim that the signs of iron deficiency, including a pale complexion, hair loss and dry skin are identifiable as ferritin face. But Powers and Marshall were skeptical that it is possible to diagnose low iron via selfie.

Though some people with restrictive diets may have trouble getting enough iron each day, Marshall said that isn’t usually the cause of deficiency in the US. More common causes are blood loss and digestive conditions.

Women are more likely than men to have iron deficiency because of the loss of blood that comes with menstruation. Women who experience heavy periods are particularly susceptible.

Children and pregnant people are also at higher risk for iron deficiency because they use a lot of iron for growth and development. Rates of iron deficiency among pregnant people increase every trimester, Powers said.

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People with chronic gastrointestinal conditions such as irritable bowel syndrome and Celiac disease may not be able to absorb enough of the iron they get from their diet. Deficiency may also come about from gastrointestinal blood loss, which can be an early sign of colon cancer.

Endurance athletes require more iron than most people, so they are also more likely to be deficient. One of the signs of deficiency is not being able to exercise as hard as you used to.

If a person eats well, gets good sleep and is “doing everything else that you associate with optimal health, but they’re still really tired, then I think it’s very reasonable to check their ferritin,” Powers said. “It’s an easy test, and there’s an easy intervention.”

Taking oral iron supplements can alleviate symptoms in weeks or months. If that course of action helps, it means low iron was contributing to your health problems. But it’s important to work with your doctor to figure out why your iron levels were low to begin with, Marshall said.

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据美国血液学会称，缺铁的人数比缺其他任何微量营养素的人数都多。但许多人在发现缺铁之前，会忍受疲劳、虚弱、思维迟钝和其他症状数月甚至数年。

根据2024年的一项研究，美国近三分之一的成年人可能缺铁。而对儿童和孕妇（高危人群）进行的常规筛查可能会漏诊超过70%的病例。

一些网友自行诊断缺铁，认为黑眼圈和肤色苍白是缺铁的证据。社交媒体上的网红们把这种现象称为“铁蛋白脸”，这个名字来源于一种在体内储存铁元素的蛋白质。

明尼苏达大学医学副教授阿里埃拉·马歇尔博士表示，缺铁性贫血很常见，但往往未被充分认识。美国血液学会（ASH）于9月发布的新诊断指南旨在确保更多患者能够及早接受治疗。

贫血是指体内红细胞数量不足以将氧气输送到身体器官和组织的一种疾病。贫血患者可能会感到疲倦、头晕或呼吸急促，也可能出现心悸、手脚冰凉、皮肤苍白、指甲脆弱或脱发等症状。

贫血通常是由缺铁引起的。铁是维持大脑和肌肉功能所必需的，也是制造血红蛋白（血液中运输氧气的分子）的必要元素。铁储存在铁蛋白中，并被募集用于制造新生成的红细胞中的血红蛋白。当铁蛋白水平低时，意味着没有足够的铁来制造红细胞，这会导致贫血。

但缺铁也会导致类似的症状，而不会影响血红蛋白或红细胞计数。低铁还会导致不宁腿综合征和异食癖——渴望食用冰块或黏土等非食物物品。（医生尚不确定原因；这可能是身体正在从环境中获取铁的信号。）

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专家表示，如果你经常感到疲倦，以下这些健康状况可能是原因所在。

马歇尔说：“人们普遍误认为，没有贫血的缺铁不会引起症状，这绝对是一个需要纠正的错误观念。”

常规血液检查（例如检测红细胞数量的检查）无法发现尚未发展成贫血的缺铁性贫血。

“缺铁的症状可能非常轻微，或者可能由多种不同的原因引起，”德克萨斯儿童医院血液科主任、2026年指南的主要作者杰奎琳·鲍尔斯博士说。“医务人员并不总是会想到，‘哦，我需要检查一下铁指标。’”

血液中铁的含量无法准确诊断缺铁，因为它会受到饮食和进食时间的影响。鲍尔斯说，铁蛋白检测是评估铁水平的金标准。但迄今为止，还没有一个公认的检测结果阈值来判断谁缺铁。

世界卫生组织建议使用血清铁蛋白浓度低于15 ng/mL作为诊断学龄儿童和成人缺铁的指标。但研究人员对这一计算方法提出质疑，他们担心如此低的阈值会漏诊许多铁储备高于该值但仍不足的人群。

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有些血液检测实验室甚至使用更低的临界值，这意味着即使某些患者的铁蛋白水平非常低，他们的实验室检测结果也可能显示“正常”。

美国血液学会 (ASH) 最新指南规定，儿童的转铁蛋白浓度临界值应为 20 ng/mL 或更低，大多数成人为 30 ng/mL，而对于月经量过多或其他风险因素（例如素食或长期服用抗酸剂治疗反流）的患者，临界值应为 50 ng/mL 或更低。对于存在炎症问题的成人，新的临界值为 100 ng/mL，该学会建议进行一项名为转铁蛋白饱和度的额外检测。

“该指南的目标之一是强调，无论患者是否贫血，检测缺铁都非常重要，因为可以通过干预措施来预防后期并发症并解决更隐匿的症​​状，”鲍尔斯说。

马歇尔说，缺铁患者可能会出现“一系列症状，从疲倦乏力到思维迟钝或思维混乱，再到感觉想嚼冰块之类的东西”。“一个人可能出现所有这些症状，也可能只出现其中一种，或者一种症状都没有。”

社交媒体上的帖子声称，面色苍白、脱发和皮肤干燥等缺铁症状被称为“铁蛋白脸”。但鲍尔斯和马歇尔对通过自拍诊断缺铁的可能性表示怀疑。

马歇尔表示，虽然一些饮食受限的人可能难以每日摄入足够的铁，但这通常不是美国铁缺乏症的成因。更常见的原因是失血和消化系统疾病。

由于月经期间失血，女性比男性更容易出现缺铁性贫血。月经量大的女性尤其容易出现这种情况。

儿童和孕妇也更容易缺铁，因为他们生长发育需要大量铁。鲍尔斯说，孕妇缺铁的发生率在每个孕期阶段都会增加。

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专家教你了解营养补充剂的那些事

患有慢性胃肠道疾病（例如肠易激综合征和乳糜泻）的人可能无法吸收足够的膳食铁。胃肠道出血也可能导致铁缺乏，而胃肠道出血可能是结肠癌的早期征兆。

耐力运动员比大多数人需要更多的铁，因此他们也更容易缺铁。缺铁的症状之一就是无法像以前那样进行高强度运动。

鲍尔斯说：“如果一个人饮食健康、睡眠充足，并且‘做了所有你认为对保持最佳健康状态至关重要的事情，但他们仍然感到非常疲倦，那么我认为检查一下他们的铁蛋白水平是非常合理的。这是一个简单的检查，而且也很容易进行干预。”

服用口服铁剂补充剂可以在几周或几个月内缓解症状。如果这种方法有效，则意味着缺铁是导致您健康问题的原因之一。但马歇尔表示，重要的是要与医生合作，找出您最初缺铁的原因。

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