View source for Ferritin

{{Infobox protein family
| Symbol = Ferritin
| Name = Ferritin
| image = Ferritin.png
| width = 
| caption = Structure of the murine ferritin complex {{PDBe|1lb3}}<ref name="pmid12459904">; {{cite journal | vauthors = Granier T, Langlois d'Estaintot B, Gallois B, Chevalier JM, Précigoux G, Santambrogio P, Arosio P | title = Structural description of the active sites of mouse L-chain ferritin at 1.2 A resolution | journal = Journal of Biological Inorganic Chemistry | volume = 8 | issue = 1-2 | pages = 105–11 | date = January 2003 | pmid = 12459904 | doi = 10.1007/s00775-002-0389-4 }}</ref>
| Pfam = PF00210
| Pfam_clan = CL0044
| InterPro = IPR008331
| SMART = 
| PROSITE = 
| MEROPS =
| SCOP = 1fha
| TCDB = 
| OPM family = 
| OPM protein = 
| CAZy = 
| CDD =
}}
{{infobox protein
| Name = [[Ferritin light chain|ferritin, light polypeptide]]
| caption = 
| image = 
| width = 
| HGNCid = 3999
| Symbol = [[Ferritin light chain|FTL]]
| AltSymbols =
| EntrezGene = 2512
| OMIM = 134790
| RefSeq = NM_000146
| UniProt = P02792
| PDB =
| ECnumber
| Chromosome = 19
| Arm = q
| Band = 13.3–13.4
| LocusSupplementaryData =
}}
{{infobox protein
| Name = [[FTH1|ferritin, heavy polypeptide 1]]
| caption =
| image =
| width =
| HGNCid = 3976
| Symbol = [[FTH1]]
| AltSymbols = FTHL6
| EntrezGene = 2495
| OMIM = 134770
| RefSeq = NM_002032
| UniProt = P02794
| PDB =
| ECnumber =
| Chromosome = 11
| Arm = q
| Band = 13
| LocusSupplementaryData =
}}
{{infobox protein
| Name = ferritin mitochondrial
| caption = Crystallographic structure of mitochondrial ferritin.<ref name="pmid15201052">{{PDB|1r03}}; {{cite journal | vauthors = Langlois d'Estaintot B, Santambrogio P, Granier T, Gallois B, Chevalier JM, Précigoux G, Levi S, Arosio P | title = Crystal structure and biochemical properties of the human mitochondrial ferritin and its mutant Ser144Ala | journal = Journal of Molecular Biology | volume = 340 | issue = 2 | pages = 277–93 | date = July 2004 | pmid = 15201052 | doi = 10.1016/j.jmb.2004.04.036 }}</ref>
| image = Mitochondrial_Ferritin.png
| width =
| HGNCid = 17345
| Symbol = FTMT
| AltSymbols =
| EntrezGene = 94033
| OMIM = 608847
| RefSeq = NM_177478
| UniProt = Q8N4E7
| PDB =
| ECnumber =
| Chromosome = 5
| Arm = q
| Band = 23.1
| LocusSupplementaryData =
}}

'''Ferritin''' is a universal intracellular [[protein]] that stores [[iron]] and releases it in a controlled fashion. The protein is produced by almost all living organisms, including algae, bacteria, higher plants, and animals. In humans, it acts as a buffer against [[iron deficiency]] and [[iron overload]].<ref>[http://www.chemistry.wustl.edu/~edudev/LabTutorials/Ferritin/Ferritin.html Iron Use and Storage in the Body: Ferritin and Molecular Representations], Rachel Casiday and Regina Frey, Department of Chemistry, Washington University, St. Louis.</ref> Ferritin is found in most tissues as a cytosolic protein, but small amounts are secreted into the [[serum (blood)|serum]] where it functions as an iron carrier. Plasma ferritin is also an indirect [[biomarker|marker]] of the total amount of iron stored in the body, hence serum ferritin is used as a [[diagnostic test]] for [[iron-deficiency anemia]].<ref name="pmid20304033">{{cite journal | vauthors = Wang W, Knovich MA, Coffman LG, Torti FM, Torti SV | title = Serum ferritin: Past, present and future | journal = Biochimica et Biophysica Acta | volume = 1800 | issue = 8 | pages = 760–9 | date = August 2010 | pmid = 20304033 | pmc = 2893236 | doi = 10.1016/j.bbagen.2010.03.011 }}</ref>

Ferritin is a [[globular protein]] complex consisting of 24 protein subunits forming a nanocage with multiple metal–protein interactions.<ref name=Theil2012>{{cite journal|last1=Theil|first1=Elizabeth C.|title=Ferritin protein nanocages—the story|journal=Nanotechnology Perceptions|date=2012|volume=8|pages=7–16|doi=10.4024/N03TH12A.ntp.08.01|pmc=3816979}}</ref> It is the primary ''intracellular iron-storage protein'' in both [[prokaryote]]s and [[eukaryote]]s, keeping iron in a soluble and non-toxic form.  Ferritin that is not combined with iron is called '''apoferritin'''.

== Gene ==

Ferritin genes are highly [[Conserved sequence|conserved]] between species. All vertebrate ferritin genes have three [[intron]]s and four [[exon]]s.<ref name="pmid11986201">{{cite journal | vauthors = Torti FM, Torti SV | title = Regulation of ferritin genes and protein | journal = Blood | volume = 99 | issue = 10 | pages = 3505–16 | date = May 2002 | pmid = 11986201 | doi = 10.1182/blood.V99.10.3505 }}</ref> In human ferritin, [[intron]]s are present between amino acid residues 14 and 15, 34 and 35, and 82 and 83; in addition, there are one to two hundred untranslated bases at either end of the combined exons.<ref name=Theil1987/> The tyrosine residue at amino acid position 27 is thought to be associated with [[biomineralization]].<ref name=deZoysa2007>{{cite journal | vauthors = De Zoysa M, Lee J | title = Two ferritin subunits from disk abalone (Haliotis discus discus): cloning, characterization and expression analysis | journal = Fish & Shellfish Immunology | volume = 23 | issue = 3 | pages = 624–35 | date = September 2007 | pmid = 17442591 | doi = 10.1016/j.fsi.2007.01.013 }}</ref>

== Protein structure ==

Ferritin is a hollow globular protein of 474&nbsp;kDa consisting of 24 subunits that is present in every cell type.<ref name=Theil1987/> Typically it has internal and external diameters of about 8 and 12&nbsp;nm, respectively.<ref>[http://www.ugr.es/~josema/Structure.html FERRITIN STRUCTURE AND ITS BIOMEDICAL IMPLICATIONS]</ref> In vertebrates, these subunits are both the [[Ferritin light chain|light (L)]] and the [[FTH1|heavy (H)]] type with an apparent molecular weight of 19&nbsp;kDa or 21&nbsp;kDa respectively; their sequences are [[Sequence homology|homologous]] (about 50% identical).<ref name=Theil1987/> Amphibians have an additional ("M") type of ferritin;<ref name=Andrews1992/> the single ferritin of plants and bacteria most closely resembles the vertebrate H-type.<ref name=Andrews1992/>  Two types have been recovered in the gastropod ''Lymnaea'', the somatic ferritin being distinct from the yolk ferritin (see below).<ref name=Andrews1992/>  An additional subunit resembling ''Lymnaea'' soma ferritin is associated with shell formation in the pearl oyster.<ref name='Zhang2003'>{{cite journal | vauthors = Zhang Y, Meng Q, Jiang T, Wang H, Xie L, Zhang R | title = A novel ferritin subunit involved in shell formation from the pearl oyster (Pinctada fucata) | journal = Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology | volume = 135 | issue = 1 | pages = 43–54 | date = May 2003 | pmid = 12781972 | doi = 10.1016/S1096-4959(03)00050-2 }}</ref>  Two types are present in the parasite ''[[Schistosoma]]'', one in males, the other in females.<ref name=Andrews1992/>  All the aforementioned ferritins are similar, in terms of their primary sequence, with the vertebrate H-type.<ref name=Andrews1992/>  In ''E. coli'', a 20% similarity to human H-ferritin is observed.<ref name=Andrews1992/>  Inside the ferritin shell, iron ions form [[crystallite]]s together with [[phosphate]] and [[hydroxide]] ions. The resulting particle is similar to the mineral [[ferrihydrite]]. Each ferritin complex can store about 4500 [[iron]] (Fe<sup>3+</sup>) ions.<ref name=Theil1987/><ref name='Andrews1992'>{{cite journal | vauthors = Andrews SC, Arosio P, Bottke W, Briat JF, von Darl M, Harrison PM, Laulhère JP, Levi S, Lobreaux S, Yewdall SJ | title = Structure, function, and evolution of ferritins | journal = Journal of Inorganic Biochemistry | volume = 47 | issue = 3–4 | pages = 161–74 | year = 1992 | pmid = 1431878 | doi = 10.1016/0162-0134(92)84062-R }}</ref>

Some ferritin complexes in [[vertebrate]]s are hetero-oligomers of two highly related [[gene]] products with slightly different [[physiological]] properties. The ratio of the two [[Homology (biology)|homologous]] proteins in the complex depends on the relative expression levels of the two genes.

[[Mitochondrial ferritin]] was recently identified as a protein precursor, and is classified as a metal-binding protein that is located within the mitochondria.<ref name="pmid11323407">{{cite journal | vauthors = Levi S, Corsi B, Bosisio M, Invernizzi R, Volz A, Sanford D, Arosio P, Drysdale J | title = A human mitochondrial ferritin encoded by an intronless gene | journal = The Journal of Biological Chemistry | volume = 276 | issue = 27 | pages = 24437–40 | date = July 2001 | pmid = 11323407 | doi = 10.1074/jbc.C100141200 }}</ref> After the protein is taken up by the mitochondria it can be processed into a mature protein and assemble to form functional ferritin shells. Its structure was determined at 1.70 angstroms through the use of X-ray diffraction and contains 182 residues. It is 67% helical. The [[Ramachandran plot]]<ref>{{cite web|url=http://www.rcsb.org/pdb/images/1R03_ram_m_500.pdf|title=MolProbity Ramachandran analysis|archiveurl=https://web.archive.org/web/20121012105157/http://www.rcsb.org/pdb/images/1R03_ram_m_500.pdf|archivedate=12 October 2012}}</ref> shows that the structure of mitochondrial ferritin is mainly alpha helical with a low prevalence of beta sheets. Unlike other human ferritin, it appears to have no introns in its genetic code.

== Function==

=== Iron storage ===
[[File:Ferritin 3foldchannel.png|thumb|Iron Uptake through the 3-fold channel of Ferritin]]
Ferritin serves to store iron in a non-toxic form, to deposit it in a safe form, and to transport it to areas where it is required.<ref>{{cite journal | vauthors = Seckback J | title = Ferreting out the secrets of plant ferritin - A review | journal = Journal of Plant Nutrition | volume = 5 | issue = 4–7 | pages = 369–394 | year = 1982 | doi = 10.1080/01904168209362966 }}</ref>  The function and structure of the expressed ferritin protein varies in different cell types.  This is controlled primarily by the amount and stability of [[mRNA]]. mRNA concentration is further tweaked by changes to how it is stored and how efficiently it is transcribed.<ref name=Theil1987>{{cite journal | vauthors = Theil EC | title = Ferritin: structure, gene regulation, and cellular function in animals, plants, and microorganisms | journal = Annual Review of Biochemistry | volume = 56 | issue = 1 | pages = 289–315 | year = 1987 | pmid = 3304136 | doi = 10.1146/annurev.bi.56.070187.001445 }}</ref>  The presence of iron itself is a major trigger for the production of ferritin,<ref name=Theil1987/> with some exceptions (such as the yolk ferritin of the gastropod ''[[Lymnaea]]'', which lacks an iron-responsive unit).<ref name=Andrews1992/>

Free iron is [[toxic]] to [[Cell (biology)|cells]] as it acts as a catalyst in the formation of free radicals from [[reactive oxygen species]] via the [[Fenton reaction]].<ref>{{cite journal | vauthors = Orino K, Lehman L, Tsuji Y, Ayaki H, Torti SV, Torti FM | title = Ferritin and the response to oxidative stress | journal = The Biochemical Journal | volume = 357 | issue = Pt 1 | pages = 241–7 | date = July 2001 | pmid = 11415455 | pmc = 1221947 | doi = 10.1042/0264-6021:3570241 }}</ref> Hence vertebrates evolve an elaborate set of protective mechanisms to bind iron in various [[Biological tissue|tissue]] compartments{{discuss}}. Within cells, iron is stored in a protein complex as ferritin or [[hemosiderin]]. Apoferritin binds to free ferrous iron and stores it in the ferric state. As ferritin accumulates within cells of the [[reticuloendothelial system]], protein aggregates are formed as [[hemosiderin]]. Iron in ferritin or hemosiderin can be extracted for release by the RE cells although hemosiderin is less readily available. Under [[steady state]] conditions, the [[Blood serum|serum]] ferritin level correlates with total body iron stores; thus, the serum ferritin FR5Rl is the most convenient laboratory test to estimate iron stores.

Because iron is an important mineral in mineralization, ferritin is employed in the shells of organisms such as molluscs to control the concentration and distribution of iron, thus sculpting shell morphology and colouration.<ref name='Jackson2007'>{{cite journal | vauthors = Jackson DJ, Wörheide G, Degnan BM | title = Dynamic expression of ancient and novel molluscan shell genes during ecological transitions | journal = BMC Evolutionary Biology | volume = 7 | pages = 160 | year = 2007 | pmid = 17845714 | pmc = 2034539 | doi = 10.1186/1471-2148-7-160 }}</ref><ref>{{cite journal | vauthors = Yano M, Nagai K, Morimoto K, Miyamoto H | title = Shematrin: a family of glycine-rich structural proteins in the shell of the pearl oyster Pinctada fucata | journal = Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology | volume = 144 | issue = 2 | pages = 254–62 | date = June 2006 | pmid = 16626988 | doi = 10.1016/j.cbpb.2006.03.004 }}</ref>  It also plays a role in the haemolymph of the [[polyplacophora]] where it serves to rapidly transport iron to the mineralizing [[radula]].<ref>{{cite journal | vauthors = Kyung-Suk K,  Webb  J, Macey D | title = Properties and role of ferritin in the hemolymph of the chiton Clavarizona hirtosa | journal = Biochimica et Biophysica Acta (BBA) - General Subjects | volume = 884 | issue = 3 | pages = 387–394 | year = 1986 | doi = 10.1016/0304-4165(86)90188-1 }}</ref>

Iron is released from ferritin for use by ferritin degradation, which is performed mainly by [[lysosome]]s.<ref>Zhang, Y., Mikhael, M., Xu, D., Li, Y., Soe-Lin, S., Ning, B., ... & Ponka, P. (2010). Lysosomal proteolysis is the primary degradation pathway for cytosolic ferritin and cytosolic ferritin degradation is necessary for iron exit. Antioxidants & redox signaling, 13(7), 999-1009.</ref>

=== Ferroxidase activity ===

Vertebrate ferritin consists of two or three subunits which are named based on their molecular weight: L "light", H "heavy", and M "middle" subunits. The M subunit has only been reported in bullfrogs. In bacteria and archaea, ferritin consists of one subunit type.<ref name="ReferenceA">{{cite journal | vauthors = Honarmand Ebrahimi K, Hagedoorn PL, Hagen WR | title = Unity in the biochemistry of the iron-storage proteins ferritin and bacterioferritin | journal = Chemical Reviews | volume = 115 | issue = 1 | pages = 295–326 | date = January 2015 | pmid = 25418839 | doi = 10.1021/cr5004908 }}</ref> H and M subunits of eukaryotic ferritin and all subunits of bacterial and archaeal ferritin are H-type and have ferroxidase activity, which is the conversion of iron from the ferrous (Fe<sup>2+</sup>) to ferric (Fe<sup>3+</sup>) forms. This limits the deleterious reaction which occurs between ferrous iron and [[hydrogen peroxide]] known as the [[Fenton reaction]] which produces the highly damaging [[hydroxyl radical]]. The ferroxidase activity occurs at a diiron binding site in the middle of each H-type subunits.<ref name="ReferenceA"/><ref name="ReferenceB">{{cite journal | vauthors = Honarmand Ebrahimi K, Bill E, Hagedoorn PL, Hagen WR | title = The catalytic center of ferritin regulates iron storage via Fe(II)-Fe(III) displacement | journal = Nature Chemical Biology | volume = 8 | issue = 11 | pages = 941–8 | date = November 2012 | pmid = 23001032 | doi = 10.1038/nchembio.1071 }}</ref> After oxidation of Fe(II), the Fe(III) product stays metastably in the ferroxidase center and is displaced by Fe(II),<ref name="ReferenceB"/><ref>{{cite journal | vauthors = Watt RK | title = A unified model for ferritin iron loading by the catalytic center: implications for controlling "free iron" during oxidative stress | journal = Chembiochem | volume = 14 | issue = 4 | pages = 415–9 | date = March 2013 | pmid = 23404831 | doi = 10.1002/cbic.201200783 }}</ref> a mechanism that appears to be common among ferritins of all three kingdoms of life.<ref name="ReferenceA"/> The light chain of ferritin has no ferroxidase activity but may be responsible for the electron transfer across the protein cage.<ref name="pmid25348725">{{cite journal | vauthors = Carmona U, Li L, Zhang L, Knez M | title = Ferritin light-chain subunits: key elements for the electron transfer across the protein cage | journal = Chemical Communications | volume = 50 | issue = 97 | pages = 15358–61 | date = December 2014 | pmid = 25348725 | doi = 10.1039/c4cc07996e }}</ref>

=== Immune response===

Ferritin concentrations increase drastically in the presence of an infection or cancer. Endotoxins are an up-regulator of the gene coding for ferritin, thus causing the concentration of ferritin to rise. By contrast, organisms such as ''Pseudomonas'', although possessing endotoxin, cause plasma ferritin levels to drop significantly within the first 48 hours of infection. Thus, the iron stores of the infected body are denied to the infective agent, impeding its metabolism.<ref name=Ong2005>{{cite journal | vauthors = Ong DS, Wang L, Zhu Y, Ho B, Ding JL | title = The response of ferritin to LPS and acute phase of Pseudomonas infection | journal = Journal of Endotoxin Research | volume = 11 | issue = 5 | pages = 267–80 | year = 2005 | pmid = 16262999 | doi = 10.1179/096805105X58698 }}</ref>

=== Stress response ===

The concentration of ferritin has been shown to increase in response to stresses such as [[Hypoxia (medical)|anoxia]];<ref>{{cite journal | vauthors = Larade K, Storey KB | title = Accumulation and translation of ferritin heavy chain transcripts following anoxia exposure in a marine invertebrate | journal = The Journal of Experimental Biology | volume = 207 | issue = Pt 8 | pages = 1353–60 | date = March 2004 | pmid = 15010486 | doi = 10.1242/jeb.00872 }}</ref> this implies that it is an [[acute-phase protein|acute phase protein]].<ref>{{cite journal | vauthors = Beck G, Ellis TW, Habicht GS, Schluter SF, Marchalonis JJ | title = Evolution of the acute phase response: iron release by echinoderm (Asterias forbesi) coelomocytes, and cloning of an echinoderm ferritin molecule | journal = Developmental and Comparative Immunology | volume = 26 | issue = 1 | pages = 11–26 | date = January 2002 | pmid = 11687259 | doi = 10.1016/S0145-305X(01)00051-9 }}</ref>

===  Mitochondria  ===

[[Mitochondrial ferritin]] has many roles pertaining to molecular function. It participates in ferroxidase activity, binding, iron ion binding, oxidoreductase activity, ferric iron binding, metal ion binding as well as transition metal binding. Within the realm of biological processes it participates in oxidation-reduction, iron ion transport across membranes and cellular iron ion homeostasis.

=== Yolk ===

In some snails, the protein component of the egg yolk is primarily ferritin;<ref name=Bottke1988>{{cite journal | vauthors = Bottke W, Burschyk M, Volmer J | title = On the origin of the yolk protein ferritin in snails | journal = Roux's Archives of Developmental Biology | volume = 197 | issue = 7 | pages = 377–382 | year = 1988 | doi = 10.1007/BF00398988 }}</ref> this is a different ferritin, with a different genetic sequence, from the somatic ferritin.  It is produced in the midgut glands and secreted into the haemolymph, whence it is transported to the eggs.<ref name=Bottke1988/>

=== Industrial applications ===

Ferritin is also used in materials science as a precursor in making iron [[nanoparticle]]s for [[carbon nanotube]] growth by [[chemical vapor deposition]].

== Tissue distribution ==

In vertebrates, ferritin is usually found within cells, although it is also present in smaller quantities in the plasma.<ref name=Ong2005/>

== Diagnostic uses ==

[[blood plasma|Serum]] ferritin levels are measured in [[medical laboratory|medical laboratories]] as part of the iron studies workup for [[iron-deficiency anemia]].<ref name=Theil2012/> The ferritin levels measured usually have a direct correlation with the total amount of iron stored in the body. However, ferritin levels may be artificially high in cases of [[anemia of chronic disease]] where ferritin is elevated in its capacity as an inflammatory [[acute phase protein]] and not as a marker for iron overload.

=== Normal ranges ===

A normal ferritin blood level, referred to as the [[reference interval]] is determined by many [[Medical laboratory|testing laboratories]]. The ranges for ferritin can vary between laboratories but typical ranges would be between 30–300&nbsp;ng/mL (=μg/L) for males, and 18–160&nbsp;ng/mL (=μg/L) for females.
{| class="wikitable"
|+ Normal ferritin blood levels according to sex and age<ref name=WebMD>{{cite web|title=Ferritin|url=http://www.webmd.com/a-to-z-guides/ferritin#2|publisher=WebMD|accessdate=27 October 2016}}</ref>
|-
| '''Men''' || 18–270 nanograms per milliliter (ng/mL)
|-
| '''Women''' || 18–160&nbsp;ng/mL
|-
| '''Children''' (6 months to 15 years) || 7–140&nbsp;ng/mL
|-
| '''Infants''' (1 to 5 months) || 50–200&nbsp;ng/mL
|-
| '''Neonates''' || 25–200&nbsp;ng/mL
|}

=== Deficiency ===

If the ferritin level is low, there is a risk for lack of iron, which could lead to [[anemia]].

In the setting of anemia, low serum ferritin is the most [[specificity (tests)|specific]] lab test for [[iron-deficiency anemia]].<ref>{{cite journal | vauthors = Guyatt GH, Patterson C, Ali M, Singer J, Levine M, Turpie I, Meyer R | title = Diagnosis of iron-deficiency anemia in the elderly | journal = The American Journal of Medicine | volume = 88 | issue = 3 | pages = 205–9 | date = March 1990 | pmid = 2178409 | doi = 10.1016/0002-9343(90)90143-2 }}</ref> However it is less [[sensitivity (tests)|sensitive]], since its levels are increased in the blood by infection or any type of chronic inflammation,<ref name=Firkin1997>[http://www.australianprescriber.com/magazine/20/3/74/6 Interpretation of biochemical tests for iron deficiency: diagnostic difficulties related to limitations of individual tests] by Frank Firkin and Bryan Rush. Aust Prescr 1997;20:74-6</ref> and these conditions may convert what would otherwise be a low level of ferritin from lack of iron, into a value in the normal range. For this reason, low ferritin levels carry more information than those in the normal range.

Low ferritin may also indicate [[hypothyroidism]], [[Scurvy|vitamin C deficiency]] or [[celiac disease]].

Low serum ferritin levels are seen in some patients with [[restless legs syndrome]], not necessarily related to anemia, but perhaps due to low iron stores short of anemia.<ref name="sleepmed3">{{cite journal | vauthors = Kryger MH, Otake K, Foerster J | title = Low body stores of iron and restless legs syndrome: a correctable cause of insomnia in adolescents and teenagers | journal = Sleep Medicine | volume = 3 | issue = 2 | pages = 127–32 | date = March 2002 | pmid = 14592231 | doi = 10.1016/S1389-9457(01)00160-5 }}
</ref><ref>{{cite journal | vauthors = Mizuno S, Mihara T, Miyaoka T, Inagaki T, Horiguchi J | title = CSF iron, ferritin and transferrin levels in restless legs syndrome | journal = Journal of Sleep Research | volume = 14 | issue = 1 | pages = 43–7 | date = March 2005 | pmid = 15743333 | doi = 10.1111/j.1365-2869.2004.00403.x }}</ref>

A ''falsely low'' blood ferritin (equivalent to a [[false positive]] test) is very uncommon,<ref name=Firkin1997/> but can result from a [[hook effect]] of the measuring tools in extreme cases.<ref>[https://books.google.com/books?id=9VBFVkMX3N0C&pg=PA236 Page 341] in: {{cite book |author1=Burnett, David |author2=Crocker, John R. |title=The Science of Laboratory Diagnosis |publisher=ISIS Medical Media |location= |year=1999 |pages= |isbn=1-899066-62-4 |oclc= |doi= |accessdate=}}</ref>

[[Vegetarianism]] may cause low serum ferritin levels, resulting from iron deficiency, with one study finding this in 19% of vegetarians.<ref>{{cite journal | vauthors = Pongstaporn W, Bunyaratavej A | title = Hematological parameters, ferritin and vitamin B12 in vegetarians | journal = Journal of the Medical Association of Thailand = Chotmaihet Thangphaet | volume = 82 | issue = 3 | pages = 304–11 | date = March 1999 | pmid = 10410487 | url = https://www.ncbi.nlm.nih.gov/pubmed/?term=Hematological+parameters%2C+ferritin+and+vitamin+B12+in+vegetarians }}
</ref>

=== Excess ===

If  ferritin is high, there is iron in excess or else there is an acute inflammatory reaction in which ferritin is mobilized without iron excess. For example, ferritins may be high in infection without signaling body iron overload.

Ferritin is also used as a [[Biomarker|marker]] for [[Iron overload|iron overload disorder]]s, such as [[hemochromatosis]] or [[hemosiderosis]]. [[Adult-onset Still's disease]], some [[porphyrias]], and [[hemophagocytic lymphohistiocytosis]]/[[macrophage activation syndrome]] are diseases in which the ferritin level may be abnormally raised.

As ferritin is also an [[acute phase proteins|acute-phase reactant]], it is often elevated in the course of [[disease]]. A normal [[C-reactive protein]] can be used to exclude elevated ferritin caused by acute phase reactions. {{Citation needed|date=October 2017}}

According to a study of [[anorexia nervosa]] patients, ferritin can be elevated during periods of acute [[malnutrition|malnourishment]], perhaps due to iron going into storage as intravascular volume and thus the number of red blood cells falls.<ref>{{cite journal | vauthors = Kennedy A, Kohn M, Lammi A, Clarke S | title = Iron status and haematological changes in adolescent female inpatients with anorexia nervosa | journal = Journal of Paediatrics and Child Health | volume = 40 | issue = 8 | pages = 430–2 | date = August 2004 | pmid = 15265182 | doi = 10.1111/j.1440-1754.2004.00432.x }}</ref>

Another study suggests that due to the catabolic nature of [[anorexia nervosa]], isoferritins may be released. Furthermore, ferritin has significant non storage roles within the body, such as protection from [[oxidative damage]]. The rise of these isoferritins may contribute to an overall increase in ferritin concentration. The measurement of ferritin through [[immunoassay]] or immunoturbidimeteric methods may also be picking up these isoferritins thus not a true reflection of iron storage status.<ref>{{cite journal | vauthors = Tran J, Story C, Moore D, Metz M | title = Unexpected increased ferritin concentration in patients with anorexia nervosa | journal = Annals of Clinical Biochemistry | volume = 50 | issue = Pt 5 | pages = 504–6 | date = September 2013 | pmid = 23897102 | doi = 10.1177/0004563213490289 }}</ref>

== Applications ==

Cavities formed by ferritin and mini-ferritins ([[Dps (DNA-binding proteins from starved cells)|Dps]]) proteins have been successfully used as the reaction chamber for the fabrication of metal [[nanoparticles]] (NPs).<ref>{{cite journal | vauthors = Kasyutich O, Ilari A, Fiorillo A, Tatchev D, Hoell A, Ceci P | title = Silver Ion Incorporation and Nanoparticle Formation inside the Cavity ofPyrococcus furiosusFerritin: Structural and Size-Distribution Analyses | volume = 132 | issue = 10 | pages = 3621–7 | date = March 2010 | pmid = 20170158 | doi = 10.1021/ja910918b }}</ref><ref>{{cite journal | vauthors = Uchida M, Flenniken ML, Allen M, Willits DA, Crowley BE, Brumfield S, Willis AF, Jackiw L, Jutila M, Young MJ, Douglas T | title = Targeting of Cancer Cells with Ferrimagnetic Ferritin Cage Nanoparticles | journal = Journal of the American Chemical Society | volume = 128 | issue = 51 | pages = 16626–33 | date = December 2006 | pmid = 17177411 | doi = 10.1021/ja0655690 }}</ref><ref>{{cite journal | vauthors = Li M, Viravaidya C, Mann S | title = Polymer-Mediated Synthesis of Ferritin-Encapsulated Inorganic Nanoparticles | journal = Small | volume = 3 | issue = 9 | pages = 1477–81 | date = September 2007 | pmid = 17768776 | doi = 10.1002/smll.200700199 }}</ref><ref>{{cite journal | vauthors = Ueno T, Suzuki M, Goto T, Matsumoto T, Nagayama K, Watanabe Y | title = Size-Selective Olefin Hydrogenation by a Pd Nanocluster Provided in an Apo-Ferritin Cage | journal = Angewandte Chemie | volume = 43 | issue = 19 | pages = 2527–30 | date = May 2004 | pmid = 15127443 | doi = 10.1002/anie.200353436 }}</ref> [[Protein]] shells served as a template to restrain particle growth and as a coating to prevent coagulation/aggregation between NPs. Using various sizes of protein shells, various sizes of NPs can be easily synthesized for chemical, physical and bio-medical applications.<ref name=Theil2012/>

== See also ==
*[[Bacterioferritin]]
*[[DNA-binding protein from starved cells]]
*[[Ferritin light chain]]
*[[Transferrin]]

== References ==
{{reflist|30em}}

== External links ==
* {{MeshName|Ferritins}}
* [http://labtestsonline.org/understanding/analytes/ferritin/tab/test Ferritin] at Lab Tests Online
* [http://www.acb.org.uk/docs/NHLM/Ferritin.pdf Ferritin: analyte monograph] - The Association for Clinical Biochemistry and Laboratory Medicine

{{Iron-binding proteins}}
{{Metal metabolism}}
{{Blood tests}}

[[Category:Iron metabolism]]
[[Category:Blood tests]]
[[Category:Chemical pathology]]
[[Category:Acute phase proteins]]
[[Category:Storage proteins]]