Vitamin B12 deficiency overview: Difference between revisions
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'''B12 deficiency''' can potentially cause severe and irreversible damage, especially to the brain and nervous system. | '''B12 deficiency''' can potentially cause severe and irreversible damage, especially to the brain and nervous system. | ||
The daily cobalamin (vitamin B12) requirement is 1-2 mcg. An intake of 5-20 mcg/day is usual in Western diet. The total body can store 2-5 mg. 60% of vitamin B12 is efficiently absorbed via the ileum when it is bound to intrinsic factor (IF). | The daily cobalamin (vitamin B12) requirement is 1-2 mcg. An intake of 5-20 mcg/day is usual in a Western diet. The total body can store 2-5 mg. 60% of vitamin B12 is efficiently absorbed via the ileum when it is bound to intrinsic factor (IF). | ||
The first deficiency symptom that was discovered was anemia characterized by enlarged blood corpuscles, so-called [[megaloblastic anemia]]. | The first deficiency symptom that was discovered was anemia characterized by enlarged blood corpuscles, so-called [[megaloblastic anemia]]. | ||
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Far more serious is the damage to the nervous system that may occur due to deficiency. | Far more serious is the damage to the nervous system that may occur due to deficiency. | ||
==Historical Perspective== | |||
==Classification== | |||
==Pathophysiology== | |||
==Causes== | |||
==Differentiating [Disease] from Other Diseases== | |||
==Epidemiology and Demographics== | |||
==Risk Factors== | |||
For vegans, the risk is very high because none of their natural food sources contain B<sub>12</sub>. One American study found blood levels below normal in 92 % of vegans, 64 % of lacto-vegetarians, and 47% of lacto-ovo vegetarians.<ref>{{cite journal | author = Dong A and Scott SC (1982)| title = Ann Nutr Metab 26(4):209-16 }}</ref> The study applied the old normal values, so in reality a considerably greater proportion may have been deficient. | |||
==Screening== | |||
==Natural History, Complications, and Prognosis== | |||
===Natural History=== | |||
===Complications=== | |||
===Prognosis=== | |||
==Diagnosis== | |||
===Diagnostic Criteria=== | |||
===History and Symptoms=== | |||
===Physical Examination=== | |||
===Laboratory Findings=== | |||
===Imaging Findings=== | |||
===Other Diagnostic Studies=== | |||
==Treatment== | |||
===Medical Therapy=== | |||
===Surgery=== | |||
===Prevention=== | |||
==References== | ==References== | ||
{{reflist|2}} | {{reflist|2}} | ||
{{WS}} | |||
{{WH}} | {{WH}} | ||
[[Category: | [[Category:Gastroenterology]] | ||
[[Category:Hematology]] | [[Category:Hematology]] | ||
Latest revision as of 20:40, 17 June 2016
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
B12 deficiency can potentially cause severe and irreversible damage, especially to the brain and nervous system.
The daily cobalamin (vitamin B12) requirement is 1-2 mcg. An intake of 5-20 mcg/day is usual in a Western diet. The total body can store 2-5 mg. 60% of vitamin B12 is efficiently absorbed via the ileum when it is bound to intrinsic factor (IF).
The first deficiency symptom that was discovered was anemia characterized by enlarged blood corpuscles, so-called megaloblastic anemia.
The anemia is thought to be due to problems in DNA synthesis, specifically in the synthesis of thymine, which is dependent on products of the MTR reaction. Other cell lines such as white blood cells and platelets are often also low. Bone marrow examination may show megaloblastic hemopoiesis. The anemia is easy to cure with vitamin B12.
Far more serious is the damage to the nervous system that may occur due to deficiency.
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating [Disease] from Other Diseases
Epidemiology and Demographics
Risk Factors
For vegans, the risk is very high because none of their natural food sources contain B12. One American study found blood levels below normal in 92 % of vegans, 64 % of lacto-vegetarians, and 47% of lacto-ovo vegetarians.[1] The study applied the old normal values, so in reality a considerably greater proportion may have been deficient.
Screening
Natural History, Complications, and Prognosis
Natural History
Complications
Prognosis
Diagnosis
Diagnostic Criteria
History and Symptoms
Physical Examination
Laboratory Findings
Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Prevention
References
- ↑ Dong A and Scott SC (1982). "Ann Nutr Metab 26(4):209-16".