Editing Iron deficiency

{{Short description|State in which a body lacks enough iron to supply its needs}}
{{Other uses}}
{{Use dmy dates|date=July 2020}}
{{Infobox medical condition (new)
| name            = Iron deficiency
| image           = Heme B.svg
| caption         = [[Iron]] in [[heme]]
| field           = [[Hematology]]
| pronounce       = 
| synonyms        = Sideropenia, hypoferremia
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| causes          =
| risks           =
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'''Iron deficiency''', or '''sideropenia''', is the state in which a body lacks enough [[iron]] to supply its needs. Iron is present in all [[cell (biology)|cell]]s in the [[human body]] and has several vital functions, such as carrying [[oxygen]] to the tissues from the [[human lung|lung]]s as a key component of the [[hemoglobin]] protein, acting as a transport medium for electrons within the cells in the form of [[cytochrome]]s, and facilitating oxygen [[enzyme]] reactions in various tissues. Too little iron can interfere with these vital functions and lead to [[morbidity]] and [[death]].<ref name="MMWR_1998">{{cite journal | vauthors =  | title = Recommendations to prevent and control iron deficiency in the United States. Centers for Disease Control and Prevention | journal = MMWR. Recommendations and Reports | volume = 47 | issue = RR-3 | pages = 1–29 | date = April 1998 | pmid = 9563847 | url = https://www.cdc.gov/mmwr/preview/mmwrhtml/00051880.htm }}</ref>

Total body iron averages approximately 3.8 g in men and 2.3 g in women. In [[blood plasma]], iron is carried tightly bound to the protein [[transferrin]]. Several mechanisms control [[iron metabolism]] and safeguard against iron deficiency. The main regulatory mechanism is situated in the gastrointestinal tract. Most iron absorption occurs in the [[duodenum]], the first section of the small intestine. Several dietary factors may affect iron absorption. Iron deficiency develops when iron loss is not sufficiently compensated by the intake of iron from the diet. When this state is uncorrected, it leads to [[iron-deficiency anemia]], a common type of anemia.<ref name="MMWR_1998"/> Before [[anemia]] occurs, the medical condition of iron deficiency without anemia is called [[latent iron deficiency]] (LID).

Anemia is a condition characterized by inadequate [[red blood cells]] (erythrocytes) or hemoglobin. When the body lacks sufficient amounts of iron, the production of the protein hemoglobin is reduced. Hemoglobin binds to oxygen, enabling red blood cells to supply oxygenated blood throughout the body. Women of childbearing age,<ref name="WHOInt">{{cite web |title=Women of reproductive age (15-49 years) population (thousands) |url=https://www.who.int/data/maternal-newborn-child-adolescent/indicator-explorer-new/mca/women-of-reproductive-age-(15-49-years)-population-(thousands) |website=www.who.int |language=en}}</ref> children, and people with poor diet are most susceptible to the disease. A primary cause of iron deficiency in non-pregnant women is menstrual bleeding, which accounts for their comparatively higher risk than men.<ref name=":0" /> Most cases of iron deficiency anemia are mild, alongside physical symptoms such as dizziness and shortness of breath, women with iron deficiency may also experience anxiety, depression, and restless leg syndrome.<ref name=":0">{{Cite web |last=Medrano |first=Lourdes |date=26 August 2024 |title=Maybe She's Just Tired, Maybe It's Undiagnosed Iron Deficiency |url=https://undark.org/2024/08/26/women-undiagnosed-iron-deficiency/ |website=undark.org/}}</ref> If not treated can cause problems like an [[Arrhythmia|irregular heartbeat]], [[pregnancy complication]]s, and [[Growth delay|delayed growth]] in infants and children that could affect their cognitive development and their behavior.<ref>{{cite web|website=Centers for Disease Control and Prevention|date=23 February 2011|title=Iron and Iron Deficiency|url=https://www.cdc.gov/nutrition/everyone/basics/vitamins/iron.html|access-date=12 August 2014|archive-url=https://web.archive.org/web/20140908003331/http://www.cdc.gov/nutrition/everyone/basics/vitamins/iron.html|archive-date=8 September 2014|url-status=dead}}</ref><ref>{{Cite journal |last1=McCann |first1=Samantha |last2=Perapoch Amadó |first2=Marta |last3=Moore |first3=Sophie E. |date=2020-07-05 |title=The Role of Iron in Brain Development: A Systematic Review |journal=Nutrients |language=en |volume=12 |issue=7 |pages=2001 |doi=10.3390/nu12072001 |doi-access=free |issn=2072-6643 |pmc=7400887 |pmid=32635675}}</ref>

==Signs and symptoms==
[[File:Iron-deficiency anaemia world map-Deaths per million persons-WHO2012.svg|thumb|upright=1.3|Deaths due to iron-deficiency anemia per million persons in 2012 {{Div col|small=yes|colwidth=10em}}{{legend|#ffff20|0}}{{legend|#ffe820|1}}{{legend|#ffd820|2–3}}{{legend|#ffc020|4–5}}{{legend|#ffa020|6–8}}{{legend|#ff9a20|9–12}}{{legend|#f08015|13–19}}{{legend|#e06815|20–30}}{{legend|#d85010|31–74}}{{legend|#d02010|75–381}}{{div col end}}]] [[File:Iron-deficiency anaemia world map - DALY - WHO2004.svg|thumb|upright=1.3|[[Disability-adjusted life year]] for iron-deficiency anemia per 100,000&nbsp;inhabitants in 2004<ref>{{cite web |url=https://www.who.int/entity/healthinfo/statistics/bodgbddeathdalyestimates.xls |title=Mortality and Burden of Disease Estimates for WHO Member States in 2002|format=xls |website=World Health Organization|year=2002 }}</ref>{{Div col|small=yes|colwidth=10em}}
{{legend|#b3b3b3|no data}}
{{legend|#ffff65|less than 50}}
{{legend|#fff200|50–100}}
{{legend|#ffdc00|100–150}}
{{legend|#ffc600|150–200}}
{{legend|#ffb000|200–250}}
{{legend|#ff9a00|250–300}}
{{legend|#ff8400|300–350}}
{{legend|#ff6e00|350–400}}
{{legend|#ff5800|400–450}}
{{legend|#ff4200|450–500}}
{{legend|#ff2c00|500–1000}}
{{legend|#cb0000|more than 1000}}
{{div col end}}]]

<ref name=":5">{{Cite journal |last1=Smith |first1=Graham A. |last2=Fisher |first2=Sheila A. |last3=Doree |first3=Carolyn |last4=Di Angelantonio |first4=Emanuele |last5=Roberts |first5=David J. |date=2014-07-03 |title=Oral or parenteral iron supplementation to reduce deferral, iron deficiency and/or anaemia in blood donors |journal=The Cochrane Database of Systematic Reviews |volume=2014 |issue=7 |pages=CD009532 |doi=10.1002/14651858.CD009532.pub2 |issn=1469-493X |pmid=24990381|pmc=11019466 }}</ref> Symptoms of iron deficiency can occur even before the condition has progressed to iron deficiency anemia.

Symptoms of iron deficiency are not unique to iron deficiency (i.e. not [[pathognomonic]]). Iron is needed for many enzymes to function normally, so a wide range of symptoms may eventually emerge, either as the secondary result of the anemia or as other primary results of iron deficiency. Common symptoms of iron deficiency include:<ref name=":3">{{Cite web |date=2017-10-23 |title=Iron deficiency anaemia |url=https://www.nhs.uk/conditions/iron-deficiency-anaemia/ |access-date=2025-01-03 |website=nhs.uk |language=en}}</ref>
* [[Fatigue (physical)|fatigue]]
* [[dizziness]]/[[lightheadedness]]
* [[pallor]]
* headache
* shortness of breath
Less common symptoms of iron deficiency include:<ref name=":3" />
* [[hair loss]]
* [[Myoclonus|twitches]]
* [[irritability]]
* [[Muscle weakness|weakness]]
* [[Pica (disorder)|pica]]
* [[Brittle nails|brittle]] or [[Nail disease#Shape and texture|grooved nails]]
* hair thinning
* [[Plummer–Vinson syndrome]]: painful atrophy of the [[mucous membrane]] covering the [[tongue]], the [[human pharynx|pharynx]] and the [[esophagus]]
* impaired [[immune function]]<ref>{{cite journal | vauthors = Wintergerst ES, Maggini S, Hornig DH | title = Contribution of selected vitamins and trace elements to immune function | journal = Annals of Nutrition & Metabolism | volume = 51 | issue = 4 | pages = 301–23 | year = 2007 | pmid = 17726308 | doi = 10.1159/000107673 | s2cid = 1108612 | url = http://doc.rero.ch/record/304705/files/S0029665108006939.pdf }}</ref>
* [[pagophagia]]
* [[desiderosmia]]<ref>{{Cite journal |last1=Hansen |first1=Bryar R. |last2=Bottner |first2=Wayne A. |last3=Ravindran |first3=Aishwarya |last4=DeJesus |first4=Ramona |last5=Go |first5=Ronald S. |date=2017 |title=Desiderosmia (olfactory craving): A novel symptom associated with iron deficiency anemia |url=https://onlinelibrary.wiley.com/doi/10.1002/ajh.24706 |journal=American Journal of Hematology |language=en |volume=92 |issue=6 |pages=E93–E94 |doi=10.1002/ajh.24706 |pmid=28240803 |issn=1096-8652}}</ref><ref>{{Cite journal |last=Yanardag Acik |first=Didar |date=May 2019 |title=Recognizing the unusual findings: Cases of desiderosmia |journal=Clinical Case Reports |language=en |volume=7 |issue=5 |pages=953–954 |doi=10.1002/ccr3.2126 |issn=2050-0904 |pmc=6509666 |pmid=31110722}}</ref>
* [[restless legs syndrome]] 
* in chronic cases, increase in blood pressure<ref>{{Cite journal |last1=Galan |first1=Pilar |last2=Vergnaud |first2=Anne-Claire |last3=Tzoulaki |first3=Ioanna |last4=Buyck |first4=Jean-François |last5=Blacher |first5=Jacques |last6=Czernichow |first6=Sébastien |last7=Hercberg |first7=Serge |date=2010 |title=Low total and nonheme iron intakes are associated with a greater risk of hypertension |url=https://pubmed.ncbi.nlm.nih.gov/19923383/ |journal=The Journal of Nutrition |volume=140 |issue=1 |pages=75–80 |doi=10.3945/jn.109.114082 |issn=1541-6100 |pmid=19923383}}</ref>

Continued iron deficiency may progress to [[anemia]] and progressive fatigue. Iron deficiency can also cause an elevated [[platelet]] count ([[thrombocytosis]]). Low iron levels in the blood may make some people ineligible to donate blood.

===Signs and symptoms in children===
Iron deficiency in children can progress slowly and the signs and symptoms may not be obvious. The most common symptom in children is appearing tired and pale.<ref>{{Cite journal |last1=Touhy |first1=Patrick C. |last2=Albertini |first2=Laurie W. |last3=Thompson |first3=Lindsay A. |date=2023-06-01 |title=What Parents Should Know About Iron-Deficiency Anemia in Children |url=https://jamanetwork.com/journals/jamapediatrics/fullarticle/2804208 |journal=JAMA Pediatrics |volume=177 |issue=6 |pages=651 |doi=10.1001/jamapediatrics.2023.0653 |pmid=37093592 |issn=2168-6203}}</ref>
* [[Pallor|pale skin]]
* [[fatigue]]
* slowed growth and development
* [[Anorexia (symptom)|poor appetite]]
* decrease in the size of testes
* [[Behavior|behavioral problems]]
* abnormal rapid breathing
* frequent [[infection]]

=== Iron requirements in young children to teenagers ===
{| class="wikitable"
!Age group
!Recommended daily<br>amount of iron<ref name=":4">{{Cite web|url=https://www.mayoclinic.org/healthy-lifestyle/childrens-health/in-depth/iron-deficiency/art-20045634|title=Is your child getting enough iron?|website=Mayo Clinic|access-date=26 April 2019}}</ref>
|-
|7–12 months
|11&nbsp;mg
|-
|1–3 years
|7&nbsp;mg
|-
|4–8 years
|10&nbsp;mg
|-
|9–13 years
|8&nbsp;mg
|-
|14–18 years, girls
|15&nbsp;mg
|-
|14–18 years, boys
|11&nbsp;mg
|}

==Causes==
Iron deficiency can be caused by many factors and health conditions and in many cases it can be treated with iron supplements.<ref name=":3" /> In women, blood loss from heavy periods is a common cause of iron deficiency.<ref name=":3" /> Pregnant women are at risk of iron deficiency.<ref name=":3" /> Internal bleeding such as from an ulcer in the stomach or intestines is another common cause.<ref name=":3" /> Blood loss from donating blood can contribute to iron deficiency.<ref name=":5" /> There are also other factors that put people at risk including:
* blood loss ([[hemoglobin]] contains iron)
** donation
** excessive [[menstrual bleeding]]
** non-menstrual [[bleeding]]
** bleeding from the [[gastrointestinal tract]] (anus) ([[Peptic ulcer|ulcers]], [[hemorrhoid]]s, [[ulcerative colitis]], [[stomach cancer|stomach]] or [[colon cancer]], etc.)
** rarely, [[laryngological]] bleeding or from the [[respiratory tract]]
** cancer
* Diet: inadequate iron intake {{crossreference|(see {{slink||Inadequate dietary intake}} below)}}
* substances (in diet or drugs) interfering with iron absorption
** Fluoroquinolone antibiotics<ref>{{cite journal | vauthors = Badal S, Her YF, Maher LJ | title = Nonantibiotic Effects of Fluoroquinolones in Mammalian Cells | journal = The Journal of Biological Chemistry | volume = 290 | issue = 36 | pages = 22287–97 | date = September 2015 | pmid = 26205818 | pmc = 4571980 | doi = 10.1074/jbc.M115.671222 | doi-access = free }}</ref>
* [[malabsorption]] syndromes
* [[inflammation]] where it is [[Evolutionary medicine|adaptive]] to limit bacterial growth in infection, but is also present in many other chronic diseases such as [[Inflammatory bowel disease]] and [[rheumatoid arthritis]]
* parasitic infection
Though [[genetic defects]] causing iron deficiency have been studied in rodents, there are no known genetic disorders of [[human iron metabolism]] that directly cause iron deficiency.{{Citation needed|date=January 2025}}

===Athletics===
Possible reasons that athletics may contribute to lower iron levels include mechanical [[hemolysis]] (destruction of red blood cells from physical impact), loss of iron through sweat and urine, gastrointestinal blood loss, and haematuria (presence of blood in urine).<ref name="Nielson">{{cite journal | vauthors = Nielsen P, Nachtigall D | title = Iron supplementation in athletes. Current recommendations | journal = Sports Medicine | volume = 26 | issue = 4 | pages = 207–16 | date = October 1998 | pmid = 9820921 | doi = 10.2165/00007256-199826040-00001 | s2cid = 25517866 }}{{dead link|date=December 2017|bot=medic}}{{cbignore|bot=medic}}</ref><ref name=Chatard>{{cite journal | vauthors = Chatard JC, Mujika I, Guy C, Lacour JR | title = Anaemia and iron deficiency in athletes. Practical recommendations for treatment | journal = Sports Medicine | volume = 27 | issue = 4 | pages = 229–40 | date = April 1999 | pmid = 10367333 | doi = 10.2165/00007256-199927040-00003 | series = 4 | s2cid = 32504228 }}</ref> Although small amounts of iron are excreted in sweat and urine, these losses can generally be seen as insignificant even with increased [[sweat]] and [[urine]] production, especially considering that athletes' bodies appear to become conditioned to retain iron better.<ref name="Nielson"/> [[Mechanical hemolytic anemia|Mechanical hemolysis]] is most likely to occur in high-impact sports, especially among long-distance runners who experience "foot-strike hemolysis" from the repeated impact of their feet with the ground. Exercise-induced [[gastrointestinal bleeding]] is most likely to occur in endurance athletes. [[March hemoglobinuria|Haematuria in athletes]] is most likely to occur in those that undergo repetitive impacts on the body, particularly affecting the feet (such as running on a hard road, or Kendo) and hands (e.g. [[Conga]] or [[Candombe]] drumming). Additionally, athletes in sports that emphasize weight loss (e.g. [[ballet]], [[gymnastics]], [[marathon running]], and [[cycle sport|cycling]]) as well as sports that emphasize high-[[carbohydrate]], low-[[fat]] diets, may be at an increased risk for iron deficiency.<ref name="Nielson"/><ref name="Chatard"/>

===Inadequate dietary intake===
A U.S. federal food consumption survey determined that for women and men over 19, average iron consumption from foods and beverages was 13.1 and 18.0&nbsp;mg/day, respectively. For women, 16% in the age range 14–50 years consumed less than the Estimated Average Requirement (EAR), and for men ages 19 and up, fewer than 3%.<ref>{{cite report | vauthors = Moshfegh A, Goldman J, Cleveland L | title = What we eat in America, NHANES 2001-2002: usual nutrient intakes from food compared to dietary reference intakes. | work = National Health and Nutrition Examination Survey (NHANES) | publisher = US Department of Agriculture, Agricultural Research Service | date = September 2005 | chapter-url = https://www.ars.usda.gov/SP2UserFiles/Place/80400530/pdf/0102/usualintaketables2001-02.pdf/ | archive-url = https://web.archive.org/web/20150106010550/https://www.ars.usda.gov/SP2UserFiles/Place/80400530/pdf/0102/usualintaketables2001-02.pdf | archive-date=6 January 2015 | chapter = Table A12: Iron}}</ref> Consumption data were updated in a 2014 U.S. government survey and reported that for men and women ages 20 and older the average iron intakes were, respectively, 16.6 and 12.6&nbsp;mg/day.<ref>{{cite web | url = https://www.ars.usda.gov/ARSUserFiles/80400530/pdf/1314/Table_1_NIN_GEN_13.pdf | title = What We Eat In America, NHANES 2013-2014 | work = National Health and Nutrition Examination Survey (NHANES) | publisher = US Department of Agriculture, Agricultural Research Service }}</ref> People in the U.S. usually obtain adequate amounts of iron from their diets.  However, subgroups like infants, young children, teenaged girls, pregnant women, and premenopausal women are at risk of obtaining less than the EAR.<ref name=NIHODS>{{Cite web |url=https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/ |title=Iron |work=Fact Sheet for Health Professionals |publisher=Office of Dietary Supplements. National Institutes of Health |date=February 2020 }}</ref> Socio-economic and racial differences further affect the rates of iron deficiency.<ref name=NIHODS/>

==Bioavailability==
Iron is needed for [[bacterial growth]] making its [[bioavailability]] an important factor in controlling [[infection]].<ref>{{cite journal | vauthors = Kluger MJ, Rothenburg BA | title = Fever and reduced iron: their interaction as a host defense response to bacterial infection | journal = Science | volume = 203 | issue = 4378 | pages = 374–6 | date = January 1979 | pmid = 760197 | doi = 10.1126/science.760197 | bibcode = 1979Sci...203..374K }}</ref> [[Blood plasma]] as a result carries iron tightly bound to [[transferrin]], which is taken up by cells by endocytosing transferrin, thus preventing its access to bacteria.<ref name="Nesse_1996">{{cite book | vauthors = Nesse RM, Williams GC | title = Why We Get Sick: The New Science of Darwinian Medicine |date=1996 |location=New York |edition=First | publisher = Vintage Books | isbn = 978-0-679-74674-4}}</ref>{{rp|30}} Between 15 and 20 percent of the protein content in [[human milk]] consists of [[lactoferrin]]<ref>{{cite book | vauthors = Lien EL | chapter = Modification of Infant Formula: The Case ofLactoferrin| chapter-url = https://link.springer.com/content/pdf/10.1007%2F978-1-4612-3956-7_24.pdf | veditors = Hutchens TW, Lönnerdal B | title = Lactoferrin: Interactions and Biological Functions | series = Experimental Biology and Medicine| url =  | page = 379 |date=1997 |publisher=Humana Press |location=Totowa, NJ | doi = 10.1007/978-1-4612-3956-7_24|isbn=978-1-4612-3956-7}}</ref> that binds iron. As a comparison, in cow's milk, this is only 2 percent. As a result, [[Breastfeeding|breast-fed]] babies have fewer infections.<ref name= "Nesse_1996" /> Lactoferrin is also concentrated in tears, saliva, and wounds to bind iron to limit bacterial growth. [[Egg white]] contains 12% [[conalbumin]] to withhold it from bacteria that get through the eggshell (for this reason, before antibiotics, egg white was used to treat infections).<ref name= "Nesse_1996" />{{rp|29}}

To reduce bacterial growth, plasma concentrations of iron are lowered in a variety of systemic inflammatory states due to increased production of [[hepcidin]] which is mainly released by the liver in response to increased production of pro-inflammatory cytokines such as [[interleukin-6]]. This functional iron deficiency will resolve once the source of inflammation is rectified; however, if not resolved, it can progress to [[anemia of chronic disease|anemia of chronic inflammation]].  The underlying inflammation can be caused by [[fever]],<ref>{{cite journal | vauthors = Weinberg ED | title = Iron withholding: a defense against infection and neoplasia | journal = Physiological Reviews | volume = 64 | issue = 1 | pages = 65–102 | date = January 1984 | pmid = 6420813 | doi = 10.1152/physrev.1984.64.1.65 }}</ref> [[inflammatory bowel disease]], infections, [[Heart failure|chronic heart failure]] (CHF), carcinomas, or following surgery.

Reflecting this link between iron bioavailability and bacterial growth, taking oral [[iron supplement]]s over 200&nbsp;mg/day causes a relative overabundance of iron that can alter the types of bacteria present within the gut. There have been concerns regarding [[parenteral iron]] being administered whilst [[bacteremia]] is present, although this has not been borne out in clinical practice.  A moderate iron deficiency, in contrast, can protect against acute infection, especially against organisms that reside within hepatocytes and macrophages, such as [[malaria]] and [[tuberculosis]]. This is mainly beneficial in regions with a high prevalence of these diseases and where standard treatment is unavailable.{{citation needed|date=November 2021}}

==Diagnosis==
* A [[complete blood count]] can reveal [[microcytic anemia]],<ref>{{cite book  | vauthors = Longmore M, Wilkinson IB, Rajagoplan S | title = Oxford Handbook of Clinical Medicine|edition= 6th  | publisher = [[Oxford University Press]]  | year = 2004  | pages = 626–628  | isbn = 0-19-852558-3 }}</ref> although this is not always present{{spaced ndash}}even when iron deficiency progresses to iron-deficiency anemia.
* Low serum [[ferritin]] (''see below'')
* Low [[serum iron]]
* High [[TIBC]] (total iron binding capacity), although this can be elevated in cases of anemia of chronic inflammation.
* It is possible that the [[fecal occult blood]] test might be positive if iron deficiency is the result of [[gastrointestinal bleeding]]; although the sensitivity of the test may mean that in some cases it will be negative even with enteral blood loss.

As always, laboratory values must be interpreted with the lab's [[reference values]] in mind and considering all aspects of the individual clinical situation.

Serum ferritin can be elevated in inflammatory conditions; so a normal serum ferritin may not always exclude iron deficiency, and the utility is improved by taking a concurrent C-reactive protein (CRP). The serum ferritin level viewed as "high" depends on the condition. For example, in [[inflammatory bowel disease]] the threshold is 100, whereas in [[heart failure|chronic heart failure]] (CHF) the levels are 200.{{citation needed|date=November 2021}}

==Treatment==
Before commencing treatment, there should be a definitive diagnosis of the underlying cause of iron deficiency.  This is particularly the case in older patients, who are most susceptible to [[colorectal cancer]] and the gastrointestinal bleeding it often causes. In adults, 60% of patients with iron-deficiency anemia may have underlying gastrointestinal disorders leading to chronic blood loss.<ref name="pmid8179652">{{cite journal | vauthors = Rockey DC, Cello JP | title = Evaluation of the gastrointestinal tract in patients with iron-deficiency anemia | journal = The New England Journal of Medicine | volume = 329 | issue = 23 | pages = 1691–5 | date = December 1993 | pmid = 8179652 | doi = 10.1056/NEJM199312023292303 | doi-access = free }}</ref>
It is likely that the cause of the iron deficiency will need treatment as well.

Upon diagnosis, the condition can be treated with [[iron supplements]]. The choice of the supplement will depend upon both the severity of the condition, the required speed of improvement (e.g. if awaiting elective surgery), and the likelihood of treatment being effective (e.g. if the patient has underlying [[Inflammatory bowel disease|IBD]], is undergoing [[Kidney dialysis|dialysis]], or is having [[erythropoiesis-stimulating agent|ESA]] therapy).

Examples of oral iron that are often used are [[ferrous sulfate]], [[ferrous gluconate]], or amino acid chelate tablets. Recent research suggests the replacement dose of iron, at least in the elderly with iron deficiency, may be as little as 15&nbsp;mg per day of elemental iron.<ref name="pmid16194646">{{cite journal | vauthors = Rimon E, Kagansky N, Kagansky M, Mechnick L, Mashiah T, Namir M, Levy S | title = Are we giving too much iron? Low-dose iron therapy is effective in octogenarians | journal = The American Journal of Medicine | volume = 118 | issue = 10 | pages = 1142–7 | date = October 2005 | pmid = 16194646 | doi = 10.1016/j.amjmed.2005.01.065 }}</ref>

Low-certainty evidence suggests that IBD-related anemia treatment with [[Intravenous iron infusion|Intravenous (IV) iron infusion]] may be more effective than [[Oral iron|oral iron therapy]], with fewer people needing to stop treatment early due to adverse effects.<ref name=":02">{{Cite journal |last1=Gordon |first1=Morris |last2=Sinopoulou |first2=Vassiliki |last3=Iheozor-Ejiofor |first3=Zipporah |last4=Iqbal |first4=Tariq |last5=Allen |first5=Patrick |last6=Hoque |first6=Sami |last7=Engineer |first7=Jaina |last8=Akobeng |first8=Anthony K |date=2021 |title=Interventions for treating iron deficiency anaemia in inflammatory bowel disease |journal=Cochrane Database of Systematic Reviews |volume=1 |issue=1 |pages=CD013529 |doi=10.1002/14651858.CD013529.pub2 |pmc=8092475 |pmid=33471939}}</ref> The type of iron preparation may be an important determinant of clinical benefit. Moderate-certainty evidence suggests response to treatment may be higher when IV [[ferric carboxymaltose]], rather than IV [[iron sucrose]] preparation is used, despite very-low certainty evidence of increased adverse effects, including bleeding, in those receiving ferric carboxymaltose treatment.<ref name=":02"/>

[[Ferric maltol]], marketed as ''Accrufer'' and ''Ferracru,'' is available in oral and IV preparations. When used as a treatment for IBD-related anemia, very low certainty evidence suggests a marked benefit with oral ferric maltol compared with placebo. However, it was unclear whether the IV preparation was more effective than oral ferric maltol.<ref name=":02"/>

A Cochrane review of controlled trials comparing [[Intravenous iron infusion|intravenous (IV) iron therapy]] with [[Iron supplement|oral iron]] supplements in people with [[chronic kidney disease]], found low-certainty evidence that people receiving IV-iron treatment were 1.71 times as likely to reach their target [[hemoglobin]] levels.<ref name=":1">{{Cite journal |last1=O'Lone |first1=Emma L |last2=Hodson |first2=Elisabeth M |last3=Nistor |first3=Ionut |last4=Bolignano |first4=Davide |last5=Webster |first5=Angela C |author-link5=Angela Webster |last6=Craig |first6=Jonathan C |date=2019 |editor-last=Cochrane Kidney and Transplant Group |title=Parenteral versus oral iron therapy for adults and children with chronic kidney disease |journal=Cochrane Database of Systematic Reviews |language=en |volume=2019 |issue=2 |pages=CD007857 |doi=10.1002/14651858.CD007857.pub3 |pmc=6384096 |pmid=30790278}}</ref> Overall, hemoglobin was 0.71g/dl higher than those treated with oral iron supplements. Iron stores in the liver, estimated by serum [[ferritin]], were also 224.84&nbsp;μg/L higher in those receiving IV-iron.<ref name=":1" /> However there was also low-certainty evidence that allergic reactions were more likely following IV-iron therapy. It was unclear whether the type of iron therapy administration affects the risk of death from any cause, including cardiovascular, nor whether it may alter the number of people who may require a blood transfusion or dialysis.<ref name=":1" />

===Food sources===
Mild iron deficiency can be prevented or corrected by eating iron-rich foods and cooking in an iron skillet. Because iron is a requirement for most plants and animals, a wide range of foods provide iron. Good sources of dietary iron have [[heme]] iron, as this is most easily absorbed and is not inhibited by medication or other dietary components. Two examples are [[red meat]] and [[poultry]].<ref>{{cite journal | vauthors = Defoliart G | year = 1992 | title = Insects as Human Food | journal = Crop Protection | volume = 11 | issue = 5| pages = 395–99 | doi=10.1016/0261-2194(92)90020-6}}</ref><ref>{{cite journal | vauthors = Bukkens SG | year = 1997 | title = The Nutritional Value of Edible Insects | journal = Ecol. Food. Nutr. | volume = 36 | issue = 2–4| pages = 287–319 | doi=10.1080/03670244.1997.9991521| bibcode = 1997EcoFN..36..287B }}</ref> Non-heme sources contain iron, though the iron is less bioavailable. Examples are [[lentil]]s, [[bean]]s, [[leafy vegetable]]s, [[pistachio]]s, [[tofu]], fortified bread, and fortified breakfast cereals.

Iron from different foods is absorbed and processed differently by the body; for instance, iron in meat (heme iron source) is more easily absorbed than iron in grains and vegetables ("non-heme" iron sources).<ref>{{cite web | url = http://www.eatwell.gov.uk/healthissues/irondeficiency/ | title = Iron deficiency | archive-url = https://web.archive.org/web/20060808184739/http://www.eatwell.gov.uk/healthissues/irondeficiency/ | archive-date=8 August 2006 | work = UK Food Standards Agency }}</ref> Minerals and chemicals in one type of food may also inhibit absorption of iron from another type of food eaten at the same time.<ref>{{cite web | url = https://www.nlm.nih.gov/medlineplus/ency/article/002422.htm | title = Iron in diet | work = MedlinePlus | publisher = U.S. National Library of Medicine }}</ref> For example, [[oxalate]]s and [[phytic acid]] form insoluble complexes which bind iron in the gut before it can be absorbed.

Because iron from plant sources is less easily absorbed than the heme-bound iron of animal sources, [[vegetarian]]s and [[vegan]]s should have a somewhat higher total daily iron intake than those who eat meat, fish, or poultry.<ref>{{cite web | vauthors = Reed M | author-link1 = Reed Mangels | url = http://www.vrg.org/nutrition/iron.htm | title = Iron in the vegan diet | work = The Vegetarian Resource Group }}</ref> [[Legume]]s and dark-green leafy vegetables like [[broccoli]], [[kale]] and Asian greens are especially good sources of iron for vegetarians and vegans. However, [[spinach]] and [[Swiss chard]] contain oxalates that bind iron, making them almost entirely unavailable for absorption.{{citation needed|date=July 2017}} Iron from non-heme sources is more readily absorbed if consumed with foods that contain either heme-bound iron or [[vitamin C]]. This is due to a hypothesized "meat factor" which enhances iron absorption.<ref>{{cite web | url = http://www.merckmanuals.com/home/disorders-of-nutrition/minerals/iron-deficiency-and-toxicity | title = Iron | work = The Merck Manuals Online Medical Library | access-date = 27 October 2015 | archive-date = 17 October 2015 | archive-url = https://web.archive.org/web/20151017034423/http://www.merckmanuals.com/home/disorders-of-nutrition/minerals/iron-deficiency-and-toxicity | url-status = dead }}</ref> The benefits of eating seasonings or condiments that have been fortified with iron for people with iron deficiencies are not clear.<ref name=":2">{{Cite journal |last1=Jalal |first1=Chowdhury SB |last2=De-Regil |first2=Luz Maria |last3=Pike |first3=Vanessa |last4=Mithra |first4=Prasanna |date=2023-09-01 |editor-last=Cochrane Public Health Group |title=Fortification of condiments and seasonings with iron for preventing anaemia and improving health |journal=Cochrane Database of Systematic Reviews |language=en |volume=2023 |issue=9 |pages=CD009604 |doi=10.1002/14651858.CD009604.pub2 |pmc=10472972 |pmid=37665781}}</ref> There is some evidence that iron-fortified condiments or seasonings may help reduce an iron deficiency, however, whether this improves a person's health and prevents the person from developing anemia is not clear.<ref name=":2" />

Following are two tables showing the richest foods in heme and non-heme iron.<ref>{{cite web |title=Food Sources of Iron |url=https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials/food-sources-select-nutrients/food-1 |url-status=live |archive-url=https://web.archive.org/web/20240326182848/https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials/food-sources-select-nutrients/food-1 |archive-date=26 Mar 2024 |work=[[Dietary Guidelines for Americans]] |publisher=[[Center for Nutrition Policy and Promotion|USDA CNPP]]; [[United States Department of Health and Human Services|HHS Office of Disease Prevention and Health Promotion]]}}</ref> The "% RDA" column is based on the [[USDA]] [[Recommended Dietary Allowance]] of 18&nbsp;mg for women aged between 19 and 50, and 8&nbsp;mg for men aged 19 and older as well as women aged 51 and older.<ref>{{cite web | url = http://www.iom.edu/Activities/Nutrition/SummaryDRIs/~/media/Files/Activity%20Files/Nutrition/DRIs/5_Summary%20Table%20Tables%201-4.pdf | title = Dietary Reference Intakes: Recommended Intakes for Individuals | archive-url = https://web.archive.org/web/20130906180147/http://www.iom.edu/Activities/Nutrition/SummaryDRIs/~/media/Files/Activity%20Files/Nutrition/DRIs/5_Summary%20Table%20Tables%201-4.pdf | archive-date = 6 September 2013 | work = National Academy of Sciences. Institute of Medicine. Food and Nutrition Board }}</ref>
{| class="wikitable"
|+Richest foods in ''heme iron''
!
!
!
! colspan="2" |% RDA
|-
!Food
!Serving size
!Iron
!18&nbsp;mg
!8&nbsp;mg
|-
|[[Pork|pork liver]]
|align="right" |3 oz (85 g)
|align="right" |15.2&nbsp;mg
|align="right" |84%
|align="right" |190%
|-
|[[lamb and mutton|lamb kidney]]
|align="right" |3 oz (85 g)
|align="right" |10.2&nbsp;mg
|align="right" |57%
|align="right" |128%
|-
|[[octopus]]
| align="right" |3 oz (85 g)
| align="right" |8.1&nbsp;mg
| align="right" |45%
|align="right" |101%
|-
|[[lamb and mutton|lamb liver]]
| align="right" |3 oz (85 g)
| align="right" |7&nbsp;mg
| align="right" |39%
|align="right" |88%
|-
|[[oyster|cooked oyster]]
| align="right" |3 oz (85 g)
| align="right" |6.6&nbsp;mg
| align="right" |37%
|align="right" |83%
|-
|[[mussel]]
| align="right" |3 oz (85 g)
| align="right" |5.7&nbsp;mg
| align="right" |32%
|align="right" |71%
|-
|[https://fdc.nal.usda.gov/fdc-app.html#/food-details/1098653/nutrients beef liver]
|align="right" |3 oz (85 g)
|align="right" |5.5&nbsp;mg
|align="right" |31%
|align="right" |69%
|-
|[[Duck as food|duck breast]]
|align="right" |3 oz (85 g)
|align="right" |3.8&nbsp;mg
|align="right" |21%
|align="right" |48%
|-
|[[bison]]
|align="right" |3 oz (85 g)
|align="right" |2.9&nbsp;mg
|align="right" |16%
|align="right" |36%
|-
|[[beef]]
|align="right" |3 oz (85 g)
|align="right" |2.5&nbsp;mg
|align="right" |14%
|align="right" |31%
|-
|[[clam]]s{{efn|Iron content in clams can vary considerably between types and modes of preparation, and the presence of aluminum could reduce iron bioavailability.<ref>{{Cite journal | vauthors = Lai JF, Dobbs J, Dunn MA | title = Evaluation of clams as a food source of iron: Total iron, heme iron, aluminum, and in vitro iron bioavailability in live and processed clams. | journal = Journal of Food Composition and Analysis | date = February 2012 | volume = 25 | issue = 1 | pages = 47–55 | doi = 10.1016/j.jfca.2011.07.004 | url = https://pubag.nal.usda.gov/catalog/567004 }}</ref> The bioaccumulation of heavy metals in clams from highly contaminated areas may make regular consumption unsafe in the long term.<ref>{{cite journal | vauthors = Hossen MF, Hamdan S, Rahman MR | title = Review on the Risk Assessment of Heavy Metals in Malaysian Clams | journal = TheScientificWorldJournal | volume = 2015 | pages = 905497 | date = 2015 | pmid = 26060840 | pmc = 4427851 | doi = 10.1155/2015/905497 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Fang ZQ, Cheung RY, Wong MH | title = Heavy metals in oysters, mussels and clams collected from coastal sites along the Pearl River Delta, South China | journal = Journal of Environmental Sciences | volume = 15 | issue = 1 | pages = 9–24 | date = January 2003 | pmid = 12602597 }}</ref>}}
| align="right" |3 oz (85 g)
| align="right" |2.4&nbsp;mg
| align="right" |13%
|align="right" |30%
|-
|[[lamb and mutton|lamb]]
|align="right" |3 oz (85 g)
|align="right" |2&nbsp;mg
|align="right" |11%
|align="right" |25%
|}
{| class="wikitable"
|+Richest foods in ''non-heme iron''
!Food
!Serving size
!Iron
!% guideline<br>''(figs don't agree)''
|-
|[[bean|raw yellow beans]]
|align="right" |100 g
|align="right" |7&nbsp;mg
|align="right" |35%
|-
|[[Spirulina (dietary supplement)|spirulina]]
|align="right" |15 g
|align="right" |4.3&nbsp;mg
|align="right" |24%
|-
|[[falafel]]
|align="right" |140 g
|align="right" |4.8&nbsp;mg
|align="right" |24%
|-
|[[soybean|soybean kernels]]
|align="right" |125 mL (~{{frac|1|2}} cup)
|align="right" |4.6&nbsp;mg
|align="right" |23%
|-
|[[spinach]]
|align="right" |125 g
|align="right" |4.4&nbsp;mg
|align="right" |22%
|-
|[[lentil]]
|align="right" |125 mL (~{{frac|1|2}} cup)
|align="right" |3.5&nbsp;mg
|align="right" |17.5%
|-
|[[treacle|treacle (CSR Australia)]]
|align="right" |20 mL (1 tbsp)
|align="right" |3.4&nbsp;mg
|align="right" |17%
|-
|[[rye bread]]
|align="right" |100 g
|align="right" |2.8&nbsp;mg
|align="right" |14%
|-
|[[buckwheat]]
|align="right" |100 g
|align="right" |2.2&nbsp;mg
|align="right" |11%
|-
|[[molasses|molasses (Bluelabel Australia)]]
|align="right" |20 mL (1 tbsp)
|align="right" |1.8&nbsp;mg
|align="right" |9%
|-
|[[ginger|candied ginger root]]
|align="right" |15 g
|align="right" |1.7&nbsp;mg
|align="right" |8.5%
|-
|[[sesame|toasted sesame seeds]]
|align="right" |10 g
|align="right" |1.4&nbsp;mg
|align="right" |7%
|-
|[[cocoa solids|cocoa (dry powder)]]
|align="right" |5 g
|align="right" |0.8&nbsp;mg
|align="right" |4%
|}

====Food recommendations for children====
Children at 6 months should start having solid food that contains enough iron, which could be found in both heme and non-heme iron.<ref>{{Cite web|url=https://www.cdc.gov/nutrition/InfantandToddlerNutrition/vitamins-minerals/iron.html|title=Iron - Infant and Toddler Nutrition|last=CDC|date=2018-12-03|website=Centers for Disease Control and Prevention|access-date=2019-04-26}}</ref>

'''Heme iron:'''
* Red meat (for example, beef, pork, lamb, goat, or venison)
* Fatty fish
* Poultry (for example, chicken or turkey)
* Eggs

'''Non-heme iron:'''
* Iron-fortified infant cereals
* Tofu
* Beans and lentils
* Dark green leafy vegetables

Iron deficiency can have serious health consequences that diet may not be able to quickly correct; hence, an [[iron supplement]] is often necessary if the iron deficiency has become symptomatic.

===Blood transfusion===
[[Blood transfusion]] is sometimes used to treat iron deficiency with hemodynamic instability.<ref name="AABBfive">{{Citation |author1 = American Association of Blood Banks |author1-link = American Association of Blood Banks |date = 24 April 2014 |title = Five Things Physicians and Patients Should Question |publisher = American Association of Blood Banks |work = [[Choosing Wisely]]: an initiative of the [[ABIM Foundation]] |url = http://www.choosingwisely.org/doctor-patient-lists/american-association-of-blood-banks/ |access-date = 25 July 2014 |archive-url = https://web.archive.org/web/20140924075027/http://www.choosingwisely.org/doctor-patient-lists/american-association-of-blood-banks/ |archive-date = 24 September 2014 |url-status = dead }}, which cites
* {{cite book|author1=AABB|title=Guidelines for Patient Blood Management and Blood|date=2011|isbn=978-1-56395-333-0|url=http://marketplace.aabb.org/EbusPPROD/Default.aspx?TabID=55&productId=1845|access-date=28 July 2014|archive-url=https://web.archive.org/web/20141015211139/http://marketplace.aabb.org/EbusPPROD/Default.aspx?TabID=55&productId=1845|archive-date=15 October 2014|url-status=dead}}
* {{cite journal | vauthors = Lin DM, Lin ES, Tran MH | title = Efficacy and safety of erythropoietin and intravenous iron in perioperative blood management: a systematic review | journal = Transfusion Medicine Reviews | volume = 27 | issue = 4 | pages = 221–34 | date = October 2013 | pmid = 24135037 | doi = 10.1016/j.tmrv.2013.09.001 }}</ref> Sometimes transfusions are considered for people who have chronic iron deficiency or who will soon go to surgery, but even if such people have low hemoglobin, they should be given oral treatment or intravenous iron.<ref name="AABBfive"/>

;Intravenous iron therapy for non-anemic, iron-deficient adults
Current evidence is limited to base any recommendations that intravenous iron therapy is beneficial for treating non-anemic, iron-deficient adults.<ref>{{cite journal | vauthors = Miles LF, Litton E, Imberger G, Story D | title = Intravenous iron therapy for non-anaemic, iron-deficient adults | journal = The Cochrane Database of Systematic Reviews | volume = 2019 | pages = CD013084 | date = December 2019 | issue = 12 | pmid = 31860749 | pmc = 6924972 | doi = 10.1002/14651858.cd013084.pub2 }}</ref> Further research in this area is needed as current body of evidence is very low quality.

==Cancer research==

The presence of ''[[Helicobacter pylori]]'' in the stomach can cause inflammation and can lower the threshold for the development of [[stomach cancer|gastric cancer]].  In the setting of iron deficiency, ''H. pylori'' causes more severe inflammation and the development of premalignant lesions.<ref name="Noto2022">Noto JM, Piazuelo MB, Shah SC, Romero-Gallo J, Hart JL, Di C, Carmichael JD, Delgado AG, Halvorson AE, Greevy RA Jr, Wroblewski LE, Sharma A, Newton AB, Allaman MM, Wilson KT, Washington MK, Calcutt MW, Schey KL, Cummings BP, Flynn CR, Zackular JP, Peek RM Jr. Iron deficiency linked to altered bile acid metabolism promotes Helicobacter pylori-induced inflammation-driven gastric carcinogenesis. J Clin Invest. 2022 Mar 22:e147822. doi: 10.1172/JCI147822. Epub ahead of print. PMID 35316215</ref>  This inflammatory effect appears to be mediated, in part, through altered [[bile acid]] production including an increase in [[deoxycholic acid]], a secondary bile acid implicated in [[colorectal cancer|colon cancer]] and other [[gastrointestinal cancer]]s.<ref name = Noto2022/>

==See also==
* [[Iron overload|Haemochromatosis]] - a condition in which the body stores too much iron
* [[Bahima disease]]
* [[CO2 fertilization effect|CO<sub>2</sub> fertilization effect]]

==Notes==
{{Notelist}}

==References==
{{Reflist}}

==Further reading==
{{refbegin}}
* {{Cite book |year=2009 |vauthors=Gropper SS, Smith JL, Groff JL |chapter=Enhancers and inhibitors of iron absorption |chapter-url=https://books.google.com/books?id=rXSO9YLr72YC&pg=PA474 |title=Advanced Nutrition and Human Metabolism |edition=5th |place=Belmont, California |publisher=[[Cengage Learning|Wadsworth, Cengage Learning]] |isbn=978-0-495-11657-8 |url=https://books.google.com/books?id=rXSO9YLr72YC}}
* {{cite journal |vauthors=Umbreit J |title=Iron deficiency: a concise review |journal=American Journal of Hematology |volume=78 |issue=3 |pages=225–31 |date=March 2005 |pmid=15726599 |doi=10.1002/ajh.20249 |doi-access=free}}
* Nutrition,Iron (2018).[[Centers for Disease Control and Prevention]].
* {{cite web |title=Iron deficiency in children: Prevention tips for parents |url=https://www.mayoclinic.org/healthy-lifestyle/childrens-health/in-depth/iron-deficiency/art-20045634 |work=The Mayo Clinic |date=10 December 2019}}
* {{Cite web |title=Can Iron Deficiency Cause High Blood Pressure? |url=https://medisearch.io/blog/can-iron-deficiency-cause-high-blood-pressure |access-date=6 June 2024 |website=Medisearch}}{{Refend}}

==External links==
* {{cite web | url = https://www.cdc.gov/mmwr/preview/mmwrhtml/00051880.htm | title = Recommendations to Prevent and Control Iron Deficiency in the United States | work = U.S. Centers for Disease Control and Prevention }}
* {{cite web | title = Advice for Improving your Iron Intake | work = University of South Hampton, NHS Foundation Trust | url = http://www.uhs.nhs.uk/Media/Controlleddocuments/Patientinformation/Digestionandurinaryhealth/Adviceforimprovingyourironintake-patientinformation.pdf | archive-url = https://web.archive.org/web/20151129023838/http://www.uhs.nhs.uk/Media/Controlleddocuments/Patientinformation/Digestionandurinaryhealth/Adviceforimprovingyourironintake-patientinformation.pdf | archive-date = 29 November 2015 }}

{{Nutritional pathology}}
{{Elements in biology}}
{{Medical resources
| ICD10          = {{ICD10|E|61|1|e}}
| DiseasesDB     = 6947
}}
{{Authority control}}

[[Category:Mineral deficiencies]]
[[Category:Iron metabolism|Deficiency]]
[[Category:Red blood cell disorders]]