Medical types - can you translate this research for me?

General anesthesia and methylenetetrahydrofolate reductase deficiency

Can you tell me what this research is saying in laymen’s terms?

Background: this research caught my eye, because I have a very unusual reaction to nitrous oxide, as it causes vertigo for months after I have nitrous. (Needless to say* I have stayed far away from N20 since I found that out) The reaction I get from medical professionals leads me to think this is extremely rare.

*well, needless to say, except on the internet where it is guaranteed that someone will come along and tell me to just avoid N20.

I’ll give it a shot.

MTHFR is a genetic disorder where the person lacks the enzyme Methylenetetrahydrofolate reductase, or MTHFR. The gene coding for MTHFR is on an autosome (not a sex chromosome). The disorder is recessive, meaning that patients lack both copies of the gene (i.e. they inherit a mutant copy from each parent).

Patients with MTHFR deficiency show a range of symptoms including early hardening of the arteries and clots in the arteries and veins.

Many mutations can cause MTHFR deficiency; most patients have different mutations in each gene copy, a few have the same mutation in each copy.

Some mutations are worse than others. The mutation of a C to a T at position 677 in the gene is the worst.

Homocystine is an amino acid that is not included in proteins – it is a free amino acid. Giving patients with MTHFR deficiency nitrous oxide leads to high levels of homocystien in their blood plasma (because other amino acids such as methionine are converted to homocysteine under these conditions). High homocysteine levels are correlated with blood vessel inflammation and endothelial cell injury, and coronary artery disease.

They discuss a case study where a patient with a homozygous MTHFR deficiency (probably C677T) underwent surgery.

This article might help you some.

First what the article you linked to says: a case report of someone with MTHFR deficiency in both genes. The details of what happened are not in the abstract but elevated levels of homocysteine are implied.

The one I just cited prospectively looked at 144 individuals getting nitrous oxide for anesthesia and tested for MTHFR mutations and measured homocysteine levels. Results?

Then the key question: does it have any clinical meaning?

So maybe but they are not mentioning prolonged vertigo.

Still search for connections between acute hyperhomocysteinemia and vertigo and you can find this.

Short version - it is possible you have found a connection and asking to have your homocysteine and folate levels measured and maybe being tested for MTHFR variants (not as cheap and readily available) is not crazy. That said some level of MTHFR deficiency is apparently present in nearly half of all Americans. There is a coin flip chance you are at least a carrier without any issue going on at all. A coin flip chance I am. If you are the only significance may be what you already know - avoid nitrous oxide - and be especially careful to take your folate if you are a pregnant woman. If you are both positive there AND have baseline low folate and elevated homocysteine … that is more interesting. And something to talk to someone who actually knows this stuff (careful lots of woo associated with MTHFR).

It says:

MTHFR deficiency can cause problems with “neurological symptoms, premature arteriosclerosis, and venous and arterial thrombosis.”

MTHFR mutations come in heterozygous or homozygous. Heterozygous means there are two different genes at the allele (or locus, or the location of the gene). Homozygous means the two genes are the same.

(You get one gene from each parent. They could be the same gene (the same one from each parent) or different genes (again, one from each parent, but different ones this time), or a mutation of one or the other or both.)

If there are two different genes, the dominant gene is usually the ‘boss.’ The other one is recessive. If the genes are they same, then they do the same thing as each other.

The mutation C677T causes the most problems. This mutation causes an increase in homocysteine in the patient’s blood. Homocysteine may be associated with increased risk for cardiovascular and peripheral vascular disease. Someone with this mutation may experience an increase in homocysteine levels when exposed to nitrous oxide.

Now, I have access to the article. It is a case report of one patient. Consider single case reports carefully. Single cases are interesting but do not speak to the larger idea well.

The woman, 44, had a homozygous MTHFR mutation and a predisposition to vascular clots (from the mutation?).

She was prescribed coumadin, a blood thinner.

Six months later, she was admitted to the hospital with a GI bleed. She received blood and plasma, but then developed a clot in an artery in one of her kidneys. She recovered and went home.

She returned again with cellulitis of the foot. (She had stepped on a screw.) She was admitted to the hospital where she got antibiotics and blood thinners, but the toe also had gangrene and needed to be amputated. I believe her labs say she was already ill. I think it says her clotting factors were off and that her blood was too thin.

In preparation for the surgery, which would be done under general anesthetic, she got two units of plasma. Thirty minutes later, she had an episode of bronchospasm.

She had the surgery and nitrous oxide was not used.

She then developed pneumonia. She was already ill. She got worse. She was intubated and sent to the ICU. They tried different anticoagulents including heparin, coumadin and lovenox to manage her bleeding times which were abnormal. She also had many other abnormal labs.

Her blood pressure dropped, requiring treatment. Her heart labs were abnormal indicating damage, and that was also treated. Then on day 7,her kidneys failed, due to a clot in her kidney, requiring dialysis. On day 7 she also got a tracheotomy (yay- off the vent).

She did not get better until day 10 of her hospital stay and finally got out of the ICU on day 17. Her kidneys (and other things) slowly began to recover and she went home on day 39, but she still needed kidney dialysis as an outpatient. She continued to take coumadin and folate on an outpatient basis.

This article goes on to cite another study using 20 patients with the C677T defect where 10 got nitrous oxide and 10 did not. The ones who got the nitrous oxide had large increases in homocysteine levels after the nitrous oxide. The article points out that a study of 20 is too small to make generalizations.

The article concludes with the idea that “It is recommended that N2O be avoided in patients with MTHFR deficiency undergoing general anesthesia,” that the patients always be properly anticoagulated, and also well hydrated, monitored for clots, and that liver and kidney function be closely monitored since they clear medications from the system (and it is important they function as well as possible, especially when one is very ill). Even healthy patients should do things to avoid clots.

MTHFR is an important enzyme in metabolizing homocysteine, incidentally. So if nitrous oxide raises homocysteine levels, it makes sense to look at this.

:slight_smile: Anyone else read “MTHFR” as something entirely different? :slight_smile:


I used to do genetic testing for MTHFR mutations. We’ve heard all the jokes…

Well, I’ve been thinking that can’t be a good sign! :smiley: