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Pernicious Anaemia Society
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B12 Def caused with Nitrous Oxide dental procedures?

I was diagnosed with B12 def at ER at levels that are undetectable. Was given a shot every month for 4 months and my levels after 4 months were at 380. Based on these levels the doctor said i don't have absorption issues but after some hot discussion they sent me for IF ,Celiac ,MMA test and all came negative and they put me on a weekly shot for a month and stopped for two months and told me to take supplements. My fatigue,brain fog, headaches,ringing in ears , tingling and pins and needles situation got better but have some dizzy spells , muscle wasting, muscle weakness and anxiety. i changed my doctor and now they have restarted weekly injections for another month and monthly shots there after. All these doctors says i don't have absorption issues and it is caused by diet as i was vegan for most of my life and the nitrous oxide exposure . I believe my treatment regimen is wrong so far and i want some expert inputs on my absorption issues and treatment .

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a result of 380 4 months after a B12 shot doesn't tell you anything about absorption.

Levels will be astronomic after a shot in patients regardless of whether or not they have an absorption problem and will then fall over time. One measurement 4 months later doesn't show you have an absorption problem - a sequence of tests showing a steady level over a couple of weeks/months would imply that you don't have an absorption problem, that your stores in your liver had been rebuilt and you were now using these to maintain the levels in serum. Levels continuing to drop would demonstrate that you probably do have an absorption problem.

IF test is not very sensitive and produces false negatives 40-60% of the time depending on the exact test method - so the test is a long way from being conclusive evidence that you don't have an absorption problem.

As a vegan did you avoid all B12 fortified foods? If you had supplemented B12 and used enough fortified foods to get RDA that would be pretty persuasive evidence that the problem wasn't dietary.

The fact that the symptoms have returned would seem to imply that you need to continue with the shots.

It may be that you don't have an absorption problem but the shots have kicked off another reaction that is stopping B12 getting through to your cells unless your serum B12 levels are high.


Thank you very much for the reply. The test that showed the levels at 380 was done after a month from my last shot back in Dec 2017.All that month i have avoided B12 fortified foods as i was working on detoxifying my body and had not taken any supplements either. My diet was purely vegan but with Milk only sometimes for coffee/Tea. No other foods with high b12 availability was taken.

What is your opinion on the nitrous oxide dental procedures i had while began vegan . could that exposure of 4-5 hours have deactivated all my B12 stores and caused this deficiency. I had a serum gastrin level test that came as normal just now and the doctor rules out PA but the blood has been drawn with out 12 hour fasting though.


the nitrous oxide would have inactivated your B12 but I don't think it would explain why your B12 levels were low as my understanding is that the inactivated B12 would still be picked up in the serum B12 test.

The gastrin probably does rule out PA as it would be really high if you had PA. As far as I am aware it isn't a test that needs to be done as a fasting test.

So rather implies that the problem probably was dietary to start of with but having had injections to correct the very low levels may have thrown a huge spanner in to the works meaning that you now have a problem not with absorption but with the transfer of B12 from blood to cells. In theory an MMA test should clarify if this is going on - it's looking at a product that builds up if your cells don't have enough B12 to recycle it into a useful building block. However there are some doubts about whether this is 100% accurate.


The symptoms have started 6-10 months right after my dental procedure but it took a whole year or more to come to B12 Diagnosis. All this while they were blaming on stress and anxiety for an year and my diagnosis came when i had to go ER . I have got MMA and Homocysteince done but after giving 5 shots of b12 over a course of 5 months. Would those be accurate in that case. IF was done as well which came out negative and the MMA & HCY levels are all normal but as i said they are done after giving some b12 shots. I am not sure if they are any correct after starting the shots? With the Gastrin also coming as Normal my doctor is saying that the shots are not necessary anymore and is asking to start supplements which i am not sure . I am having gait problems like unsteadiness and if the doctor stop injections i fear i will go back to starting.


what was the strength of the supplements you were being given. oral supplements can be helpful in maintaining B12 levels but likely that you would need to take quite high doses to maintain levels where you now need them.

Also may be possible to source B12 for yourself - though I'm guessing you are based in the US rather than the UK


I am in US and i have been given 500MCG of Cyanocobalmin supplements by my dr. I am not using them but have bought 2500MCG Methyl sublinguals from Amazon. I dont know where to source injections for SI. Also could you please review my MRI below for LS/CS/Brain. Does it indicate any SACD. The doctor sounded unknown when i asked but they said they were ruling out some other issues.

Cervical MRI: Done 3/15/2018


The cervical vertebral body heights and alignment are maintained.

The visualized marrow signal is unremarkable.

The cervical spinal cord demonstrates normal signal intensity. The

par ally-imaged posterior fossa structures are unremarkable.

Level by level analysis of degenera ve changes:

C2-C3: Unremarkable

C3-C4: Minimal posterior central disc protrusion, minimal le uncovertebral

osteophytosis, and mild le degenera ve facet hypertrophy. Resul ng mild to

moderate le foraminal stenosis. No significant central canal or right

foraminal stenosis.

C4-C5: Moderate le posterior disc osteophyte touches and may minimally

indent the le ventral spinal cord. No spinal cord compression, however. Mild

central canal stenosis. Moderate to severe le foraminal stenosis. No

significant right foraminal stenosis.

C5-C6: Minimal to mild central/le paracentral disc protrusion. Minimal to

mild le greater than right uncovertebral osteophytosis. Mild central canal

stenosis, without mass effect on the spinal cord. Mild le foraminal

stenosis. No significant right foraminal stenosis.

C6-C7: Unremarkable

C7-T1: Unremarkable

Lumbar MRI: Done in 11/30/2017


There is mild straightening of the normal lumbar lordosis. Vertebral bodies

are normal in height and morphology. Marrow signal is within normal limits.

For purposes of this study lower most square type vertebral body is considered

to be L5 and there are no ribs visualized at T12. There is minimal disc

desiccation at L4-5. Disc space heights are preserved.

Conus is at the L1 level and is normal in signal and morphology.

Sagittal imaging shows no bulge or herniation at T11-12 or T12-L1.

Level by level assessment:

At L1-2 and L2-3 there is no disc bulge or herniation and no central canal or

neural foraminal narrowing.

At L3-4 there is no disc bulge or herniation and no central canal or neural

foraminal narrowing.

At L4-5 there is disc bulge and mild facet hypertrophy. There is mild lateral

recess narrowing. There is no central canal or neural foraminal narrowing.

At L5-S1 there is no disc bulge or herniation and no central canal or neural

foraminal narrowing.

Brain MRI: Done 8/14/2017 before B12 diagnosis.


The ventricles and sulci are normal in size and configura on for the

patient's age.

There is no evidence for acute infarc on on diffusion imaging. There is no

mass effect or midline shi . There are three punctate foci of increased

signal in supratentorial white ma er on T2-weighted and FLAIR imaging.

Otherwise, brain parenchyma is normal in signal.

There is no abnormal enhancement on postcontrast imaging.

Cerebellar tonsils are normally located. The sella, globes and orbits appear

grossly normal.

Vascular flow voids are maintained at the skull base.

There is mild mucosal thickening involving paranasal sinuses.


Dvpk24 I'm not a medic and I wouldn't really know where to start in reviewing the information above, though my understanding is that scans can be very easy to interpret. It sounds like they have picked up some skeletal factors that are consistent with aging -really not sure about the brain MRI - looked like there was a bit of abnormal signal but ... I'm afraid you are going to have eto talk things through with your doctor or get a second opinion.

Getting injectable B12 does seem to be quite difficult in the states - some people go to slimming clinics but sounds like that is quite expensive - if you are near the Canadian border you can get it over the counter and bring some back into the US but my understanding is that regulations mean you can't order it on-line from Canada.


Thank you very much for all your inputs.

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Like Gambit, I'm not an expert on the brain scan, but your lumbar MRI shows nothing to worry about. Anyone over about 20 will have some signs of wear and tear to their spine, and this is entirely normal. A disc bulge can cause some pain if it irritates a nerve, but equally it can repair pretty well without ever being found. If there was anything on the scan which had been concerning, they would have acted on it - but this sounds like a pretty normal spine!


Hi Dvpk24 It is true that people who undergo surgeries or dental procedures involving nitrous oxide, or who use the drug recreationally are at an elevated risk of developing a Vitamin B12 deficiency.

Nitrous oxide is a super-oxidiser when it comes to B12 and converts it to a form that the body cannot use, so if you had an absorption problem and couldn't replace the oxidised B12 with new B12 then it would be a permanent problem.

I'm not sure whether you will be able to open the link below in the U.S.


I'm not a medically trained person and wish you well.

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What will confirm my absorption problems? I had IF & Gastrin tests that came out normal. What tests i can get it done to find it?TIA.


I wish I knew but hope you find some answers soon.

Was your Folate level ever tested?

There is a complex interaction between folic acid, vitamin B12 and iron. A deficiency of one may be "masked" by excess of another so the three must always be in balance.

Symptoms of a folate deficiency can include:

symptoms related to anaemia

reduced sense of taste


numbness and tingling in the feet and hands

muscle weakness


Folic acid works closely with vitamin B12 in making red blood cells and helps iron function properly in the body

Goodnight from the U.K,


Folate when diagnosed with B12 def of <146pg/ml levels was at 17ng/ml. Then after 4 months it B12 was at 380pg/ml folate was at 17.1ng/ml.


Symptoms of SACD can occur years before being indicated in tests. Here in the UK, the guidelines state treatment of b12 deficiency should be based on clinical features, rather than any tests. Not that the doctors follow them!


If you are eating animal products like cheese, eggs, milk, meat on a regular basis and you have low b12, you are either on medications that block absorption or you just don't have absorption. Take shots 1 a month after loading doses. I also had no detectable. my loading doses went like this. 1 shot a day for a month, 2 shots a week for a month, 1 shot a week for a month and then 1 shot a month. 1ml/1cc are the same. You can also take sublingual after loading doses. I do well on the liquid 5000mg a day, every day. I hold it under my tongue for as long as possible. You can get that over the counter. Makes me so mad how stingy doctors are with B12. It has been used for so long as a placebo, I wonder if they fully understand how important it is.

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Thank you. My levels are undetectable back in Sep 2017 but i have been given irregualr shots and my levels are at 380 after 4 months. Do you suggest to start from the loading doses as you mentioned above as i might have some B12 circulating in blood due to the shots given previously. While i get the shots do i need to take sublinguals of equal strength or can take in higher does of 2500mcg.


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