Vitamin B-12 deficiency: Difference between revisions

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In [[medicine]], '''vitamin B-12 deficiency''', is a "nutritional condition produced by a deficiency of [[Vitamin B-12]] in the  diet, characterized by megaloblastic anemia. Since vitamin B 12 is not  present in plants, humans have obtained their supply from animal  products, from multivitamin supplements in the form of pills, and as  additives to food preparations. A wide variety of neuropsychiatric  abnormalities is also seen in vitamin B 12 deficiency and appears to be due to an undefined defect involving myelin synthesis."<ref>{{MeSH}}</ref>
{{subpages}}
In [[medicine]], '''vitamin B-12 deficiency''', is a "nutritional condition produced by a deficiency of [[Vitamin B-12]] in the  diet, characterized by megaloblastic anaemia. Since vitamin B 12 is not  present in plants, humans have obtained their supply from animal  products, from multivitamin supplements in the form of pills, and as  additives to food preparations. A wide variety of neuropsychiatric  abnormalities is also seen in vitamin B 12 deficiency and appears to be due to an undefined defect involving myelin synthesis."<ref>{{MeSH}}</ref>


Manifestations include [[pernicious anemia]] and [[subacute combined degeneration]].
Manifestations include [[pernicious anaemia]] and [[subacute combined degeneration]].
 
Vitamin B-12 deficiency may be combined with [[iron deficiency anaemia]].<ref name="pmid15914358">{{cite journal| author=Beyan C, Kaptan K, Beyan E, Turan M| title=The platelet count/mean corpuscular hemoglobin ratio distinguishes combined iron and vitamin B12 deficiency from uncomplicated iron deficiency. | journal=Int J Hematol | year= 2005 | volume= 81 | issue= 4 | pages= 301-3 | pmid=15914358 | doi=10.1532/IJH97.E0311 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15914358  }} </ref>


==Diagnosis==
==Diagnosis==
The MCV is not accurate.<ref name="pmid2187961">{{cite journal| author=Seward SJ, Safran C, Marton KI, Robinson SH| title=Does the mean corpuscular volume help physicians evaluate hospitalized patients with anemia? | journal=J Gen Intern Med | year= 1990 | volume= 5 | issue= 3 | pages= 187-91 | pmid=2187961 | doi=10.1007/BF02600530 | pmc= | url= }} </ref>
Vitamin B-12 deficiency may be an explanation for [[macrocytosis]]<ref name="pmid2341917">{{cite journal| author=Wymer A, Becker DM| title=Recognition and evaluation of red blood cell macrocytosis in the primary care setting. | journal=J Gen Intern Med | year= 1990 | volume= 5 | issue= 3 | pages= 192-7 | pmid=2341917 | doi= | pmc= | url= }} </ref>
 
However, the MCV is not completely accurate.<ref name="pmid10757449">{{cite journal| author=Oosterhuis WP, Niessen RW, Bossuyt PM, Sanders GT, Sturk A| title=Diagnostic value of the mean corpuscular volume in the detection of vitamin B12 deficiency. | journal=Scand J Clin Lab Invest | year= 2000 | volume= 60 | issue= 1 | pages= 9-18 | pmid=10757449 | doi= | pmc= | url= }} </ref><ref name="pmid2187961">{{cite journal| author=Seward SJ, Safran C, Marton KI, Robinson SH| title=Does the mean corpuscular volume help physicians evaluate hospitalized patients with anaemia? | journal=J Gen Intern Med | year= 1990 | volume= 5 | issue= 3 | pages= 187-91 | pmid=2187961 | doi=10.1007/BF02600530 | pmc= | url= }} </ref><ref name="pmid8154512">{{cite journal| author=Savage DG, Lindenbaum J, Stabler SP, Allen RH| title=Sensitivity of serum methylmalonic acid and total homocysteine determinations for diagnosing cobalamin and folate deficiencies. | journal=Am J Med | year= 1994 | volume= 96 | issue= 3 | pages= 239-46 | pmid=8154512 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8154512  }} </ref>:
* [[Sensitivity and specificity|Sensitivity]]: 60%<ref name="pmid2187961"/>, 64%<ref name="pmid8309266">{{cite journal| author=Pruthi RK, Tefferi A| title=Pernicious anaemia revisited. | journal=Mayo Clin Proc | year= 1994 | volume= 69 | issue= 2 | pages= 144-50 | pmid=8309266 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8309266  }} </ref> to 83%<ref name="pmid8154512">{{cite journal| author=Savage DG, Lindenbaum J, Stabler SP, Allen RH| title=Sensitivity of serum methylmalonic acid and total homocysteine determinations for diagnosing cobalamin and folate deficiencies. | journal=Am J Med | year= 1994 | volume= 96 | issue= 3 | pages= 239-46 | pmid=8154512 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8154512  }} </ref>
* [[Sensitivity and specificity|Specificity]]: 70%<ref name="pmid2187961"/>
 
B12 levels are helpful, but imperfect:
* [[Sensitivity and specificity|Sensitivity]]: 95%<ref name="pmid2339684">{{cite journal| author=Lindenbaum J, Savage DG, Stabler SP, Allen RH| title=Diagnosis of cobalamin deficiency: II. Relative sensitivities of serum cobalamin, methylmalonic acid, and total homocysteine concentrations. | journal=Am J Hematol | year= 1990 | volume= 34 | issue= 2 | pages= 99-107 | pmid=2339684 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=2339684  }} </ref><ref name="pmid7603218">{{cite journal| author=Naurath HJ, Joosten E, Riezler R, Stabler SP, Allen RH, Lindenbaum J| title=Effects of vitamin B12, folate, and vitamin B6 supplements in elderly people with normal serum vitamin concentrations. | journal=Lancet | year= 1995 | volume= 346 | issue= 8967 | pages= 85-9 | pmid=7603218 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7603218  }} </ref>
* [[Sensitivity and specificity|Specificity]]: 95%<ref name="pmid7977446">{{cite journal| author=Matchar DB, McCrory DC, Millington DS, Feussner JR| title=Performance of the serum cobalamin assay for diagnosis of cobalamin deficiency. | journal=Am J Med Sci | year= 1994 | volume= 308 | issue= 5 | pages= 276-83 | pmid=7977446 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7977446  }} </ref>
 
Folic acid levels may not help.<ref name="pmid18414954">{{cite journal| author=Ashraf MJ, Cook JR, Rothberg MB| title=Clinical utility of folic acid testing for patients with anaemia or dementia. | journal=J Gen Intern Med | year= 2008 | volume= 23 | issue= 6 | pages= 824-6 | pmid=18414954 | doi=10.1007/s11606-008-0615-z | pmc=PMC2517884 | url= }} </ref>
 
Diagnosis may be especially difficult in alcoholics.<ref name="pmid3747828">{{cite journal| author=Savage D, Lindenbaum J| title=Anaemia in alcoholics. | journal=Medicine (Baltimore) | year= 1986 | volume= 65 | issue= 5 | pages= 322-38 | pmid=3747828 | doi= | pmc= | url= }} </ref>
 
===Treatment===
Oral therapy may be effective.<ref name="pmid16034940">{{cite journal| author=Vidal-Alaball J, Butler CC, Cannings-John R, Goringe A, Hood K, McCaddon A et al.| title=Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency. | journal=Cochrane Database Syst Rev | year= 2005 | volume=  | issue= 3 | pages= CD004655 | pmid=16034940 | doi=10.1002/14651858.CD004655.pub2 | pmc= | url= }}  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17213051 Review in: Evid Based Med. 2006 Feb;11(1):9] </ref>


==References==
==References==
<references/>
<references/>

Latest revision as of 16:47, 13 May 2023

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In medicine, vitamin B-12 deficiency, is a "nutritional condition produced by a deficiency of Vitamin B-12 in the diet, characterized by megaloblastic anaemia. Since vitamin B 12 is not present in plants, humans have obtained their supply from animal products, from multivitamin supplements in the form of pills, and as additives to food preparations. A wide variety of neuropsychiatric abnormalities is also seen in vitamin B 12 deficiency and appears to be due to an undefined defect involving myelin synthesis."[1]

Manifestations include pernicious anaemia and subacute combined degeneration.

Vitamin B-12 deficiency may be combined with iron deficiency anaemia.[2]

Diagnosis

Vitamin B-12 deficiency may be an explanation for macrocytosis[3]

However, the MCV is not completely accurate.[4][5][6]:

B12 levels are helpful, but imperfect:

Folic acid levels may not help.[11]

Diagnosis may be especially difficult in alcoholics.[12]

Treatment

Oral therapy may be effective.[13]

References

  1. ↑ Anonymous (2024), Vitamin B-12 deficiency (English). Medical Subject Headings. U.S. National Library of Medicine.
  2. ↑ Beyan C, Kaptan K, Beyan E, Turan M (2005). "The platelet count/mean corpuscular hemoglobin ratio distinguishes combined iron and vitamin B12 deficiency from uncomplicated iron deficiency.". Int J Hematol 81 (4): 301-3. DOI:10.1532/IJH97.E0311. PMID 15914358. Research Blogging.
  3. ↑ Wymer A, Becker DM (1990). "Recognition and evaluation of red blood cell macrocytosis in the primary care setting.". J Gen Intern Med 5 (3): 192-7. PMID 2341917. [e]
  4. ↑ Oosterhuis WP, Niessen RW, Bossuyt PM, Sanders GT, Sturk A (2000). "Diagnostic value of the mean corpuscular volume in the detection of vitamin B12 deficiency.". Scand J Clin Lab Invest 60 (1): 9-18. PMID 10757449. [e]
  5. ↑ 5.0 5.1 5.2 Seward SJ, Safran C, Marton KI, Robinson SH (1990). "Does the mean corpuscular volume help physicians evaluate hospitalized patients with anaemia?". J Gen Intern Med 5 (3): 187-91. DOI:10.1007/BF02600530. PMID 2187961. Research Blogging.
  6. ↑ 6.0 6.1 Savage DG, Lindenbaum J, Stabler SP, Allen RH (1994). "Sensitivity of serum methylmalonic acid and total homocysteine determinations for diagnosing cobalamin and folate deficiencies.". Am J Med 96 (3): 239-46. PMID 8154512. [e]
  7. ↑ Pruthi RK, Tefferi A (1994). "Pernicious anaemia revisited.". Mayo Clin Proc 69 (2): 144-50. PMID 8309266. [e]
  8. ↑ Lindenbaum J, Savage DG, Stabler SP, Allen RH (1990). "Diagnosis of cobalamin deficiency: II. Relative sensitivities of serum cobalamin, methylmalonic acid, and total homocysteine concentrations.". Am J Hematol 34 (2): 99-107. PMID 2339684. [e]
  9. ↑ Naurath HJ, Joosten E, Riezler R, Stabler SP, Allen RH, Lindenbaum J (1995). "Effects of vitamin B12, folate, and vitamin B6 supplements in elderly people with normal serum vitamin concentrations.". Lancet 346 (8967): 85-9. PMID 7603218. [e]
  10. ↑ Matchar DB, McCrory DC, Millington DS, Feussner JR (1994). "Performance of the serum cobalamin assay for diagnosis of cobalamin deficiency.". Am J Med Sci 308 (5): 276-83. PMID 7977446. [e]
  11. ↑ Ashraf MJ, Cook JR, Rothberg MB (2008). "Clinical utility of folic acid testing for patients with anaemia or dementia.". J Gen Intern Med 23 (6): 824-6. DOI:10.1007/s11606-008-0615-z. PMID 18414954. PMC PMC2517884. Research Blogging.
  12. ↑ Savage D, Lindenbaum J (1986). "Anaemia in alcoholics.". Medicine (Baltimore) 65 (5): 322-38. PMID 3747828. [e]
  13. ↑ Vidal-Alaball J, Butler CC, Cannings-John R, Goringe A, Hood K, McCaddon A et al. (2005). "Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency.". Cochrane Database Syst Rev (3): CD004655. DOI:10.1002/14651858.CD004655.pub2. PMID 16034940. Research Blogging. Review in: Evid Based Med. 2006 Feb;11(1):9
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