Editing Megaloblastic anemia (section)

==Causes==
* [[Vitamin B12 deficiency]]:
** [[Achlorhydria]]-induced malabsorption
** Deficient intake (e.g. vegan diet)
** [[Pernicious anemia]]
** [[Gastrectomy]]
** [[Coeliac disease|Celiac disease]]
** Biological competition for vitamin B12 by [[diverticulosis]], [[fistula]], intestinal [[anastomosis]], or infection by the marine parasite ''[[Diphyllobothrium latum]] (fish tapeworm)''
** Selective [[vitamin B12]] [[malabsorption]] (congenital—[[juvenile megaloblastic anaemia 1|juvenile megaloblastic anemia 1]]—and drug-induced)
** [[Chronic pancreatitis]]
** Ileal resection and bypass
** [[Nitrous oxide]] anesthesia (usually requires repeated instances).
* [[Folate deficiency]]:
** [[Alcoholism]]
** Deficient intake
** Increased needs: [[pregnancy]], [[infant]], rapid cellular proliferation, and [[cirrhosis]]
** [[Malabsorption]] ([[Hereditary folate malabsorption|congenital]] and drug-induced)
** Intestinal and [[jejunal]] resection
** (indirect) Deficient [[thiamine]] and factors (e.g., enzymes) responsible for [[Conditions comorbid to autism spectrum disorders#Abnormal folate metabolism|abnormal folate metabolism]].
** Tea and toast diet
* Inherited Pyrimidine Synthesis Disorders: [[Orotic aciduria]]
* Inherited [[DNA]] Synthesis Disorders
* Toxins and Drugs:
** [[Folic acid]] antagonists ([[methotrexate]])
** [[Purine]] synthesis antagonists ([[6-mercaptopurine]], [[azathioprine]])
** [[Pyrimidine]] antagonists ([[cytarabine]])
** [[Phenytoin]]
** [[Nitrous Oxide]]
* [[Erythroleukemia]]
* Inborn genetic mutations of the [[Methionine synthase]] gene
* [[Acute erythroid leukemia|Di Guglielmo's syndrome]]
* [[Congenital dyserythropoietic anemia]]
* [[Copper deficiency]] resulting from an excess of zinc from unusually high oral consumption of zinc-containing denture-fixation creams has been found to be a cause.<ref>{{Cite journal| doi = 10.1212/01.wnl.0000312375.79881.94| issn = 1526-632X| volume = 71| issue = 9| pages = 639–643| last1 = Nations| first1 = S. P.| last2 = Boyer| first2 = P. J.| last3 = Love| first3 = L. A.| last4 = Burritt| first4 = M. F.| last5 = Butz| first5 = J. A.| last6 = Wolfe| first6 = G. I.| last7 = Hynan| first7 = L. S.| last8 = Reisch| first8 = J.| last9 = Trivedi| first9 = J. R.| title = Denture cream: an unusual source of excess zinc, leading to hypocupremia and neurologic disease| journal = Neurology| date = 2008-08-26| pmid = 18525032| s2cid = 19614652}}</ref><ref>{{Cite journal| doi = 10.1038/ncpneuro1008| issn = 1745-8358| volume = 5| issue = 2| pages = 106–111| last1 = Spain| first1 = Rebecca I.| last2 = Leist| first2 = Thomas P.| last3 = De Sousa| first3 = Eduardo A.| title = When metals compete: a case of copper-deficiency myeloneuropathy and anemia| journal = Nature Clinical Practice. Neurology| date = February 2009| pmid = 19194390| s2cid = 27892441}}</ref>