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I don't know that the exact process by which b12 deficiency causes neurological symptoms (subacute combined degeneration) is that well understood.

B12 (wikipedia source) is used to regenerate Folate and thereby correct anemia. Also, you can correct anemia due to either folate or b12 deficiency by giving folate. However, what giving folate has to do with b12 neuro symptoms becoming worse I don't know...
 

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it was a question on uworld. the point of the question was to identify b12 def. and pick as the answer to treat it as b12, but one of the choices was folate and under the explanation it said folate worsens B12 neurological side effects so alway make sure to identify the correct reason for the megaloblastic anemia so i was just wondering why. I think i read before that b12 def cause neurological side effect because methymalonic acid is toxic to myelin so cause degeneration of myelin
 

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it was a question on uworld. the point of the question was to identify b12 def. and pick as the answer to treat it as b12, but one of the choices was folate and under the explanation it said folate worsens B12 neurological side effects so alway make sure to identify the correct reason for the megaloblastic anemia so i was just wondering why. I think i read before that b12 def cause neurological side effect because methymalonic acid is toxic to myelin so cause degeneration of myelin
hey sorry i got ur Q wrong....neways here is explanation...
neurological symptoms r not corrected if u r treating with folate alone...
as neurological damage is due to propionic acid n methylmalonic acid accumulation in myelin....these 2 are elevated as reaction for there conversion to succinyl co A requires...only vit b12..not folate....
so if u r treating with folate alone...basic pathology for neurological symptoms is gonna continue only....
 

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Thanks @khushboo for this nice explanation but i want to clarify one thing in regards to the question asked.

How can treating neurologic symptoms due to B12 deficiency be worsened if you treat it with folate accidentally?
Treating vitamin B12 deficiency with folate does exacerbate the symptoms because it further increases the blood levels of homocysteine and methylmalonic acid worsening the neurological defects.

So it is important to differentiare b/t vitamin B 12 & folate deficiencies.
 
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Thanks @khushboo for this nice explanation but i want to clarify one thing in regards to the question asked.

Treating vitamin B12 deficiency with folate does exacerbate the symptoms because it further increases the blood levels of homocysteine and methylmalonic acid worsening the neurological defects.

So it is important to differentiare b/t vitamin B 12 & folate deficiencies.
m not agree with u...as homocysteine and methylmalonic acid level r already high...n it increases further not because u r treating with folate but because u r not treating with vit b12....conversion of methymalonic to methionine requires both vit b12 n folate...so if any one of these 2 is missing...homocysteine level gonna rise only...
 

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Thanks @khushboo for this nice explanation but i want to clarify one thing in regards to the question asked.

Treating vitamin B12 deficiency with folate does exacerbate the symptoms because it further increases the blood levels of homocysteine and methylmalonic acid worsening the neurological defects.

So it is important to differentiare b/t vitamin B 12 & folate deficiencies.
Source of this information

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2234223/

Have a look at it to interpret it by yourself.......:)
 
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UWORLD explanation

Guys I am still really confused, perhaps someone can further explain what is stated by UWORLD: "usage of folate alone can worsen demyelination and cause abnormal myelin synthesis by depleting the conc. of unmethylated cobalamin available for methylmalonyl-coa processing"?
 

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m not agree with u...as homocysteine and methylmalonic acid level r already high...n it increases further not because u r treating with folate but because u r not treating with vit b12....conversion of methymalonic to methionine requires both vit b12 n folate...so if any one of these 2 is missing...homocysteine level gonna rise only...
You mean conversion of homocysteine to methionine, right?

(Methyl-B12 gives a methyl group to homocysteine, which becomes methionine, and methyl-B12 becomes B12, having given away its methyl group)
 
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