Question Thyroid Cancer/Levothyroxine + Nitrox

[tursiops]

My wife has been on Synthroid 75mg and Nitrox for over 25 years with no side effects.

You probably mean 75 micrograms, not milligrams.
I've been on 100 mcg (microgram) Levothyroxine for maybe 20 years, thousands of dives mostly Nitrox, fair amount of time at PPO2 1.4 and 1.6. No apparent issues.

 

[Scubagermany]

Hi everyone! I am cancer-free from thyroid cancer but do NOT have a thyroid. I am on Levothyroxine and Cytomel as hormone replacement and my levels are normal.

It is safe for me to dive with Nitrox? I’ve been seeing some conflicting posts etc about it being safe, not being safe (higher risk of oxygen toxicity it seems?)

Any insights would be great!

I reached out to my doc and she didn’t have an answer for me

I have not heard of cases of dive related problems in patients with a correctly substituted hypothreosis.

 

[uncfnp]

All the above.

But if you want to be extra cautious use the very conservative PPO2 level of 1.2 for your MOD. For example, with nitrox 32 your maximum depth would be 91 feet rather than the more commonly used 1.4 (max depth 111).

 

[tursiops]

All the above.

But if you want to be extra cautious use the very conservative PPO2 level of 1.2 for your MOD. For example, with nitrox 32 your maximum depth would be 91 feet rather than the more commonly used 1.4 (max depth 111).

I'm happy to be conservative, but not to "solve" a non-problem.
I use 100 ft with 32% because it is easy to remember and matches the max depth limit of a lot of operators.

 

[Scubagermany]

I did a quick search in medical databases and all I could find was headaches related to hypoxia.
The article was not dive related though.I

So do not treat problems that are not there just as tursiops said.

BTW I dive myself with substituted hypothyreoidism and never had any problems whatsoever.

 

[uncfnp]

I'm happy to be conservative, but not to "solve" a non-problem.
I use 100 ft with 32% because it is easy to remember and matches the max depth limit of a lot of operators.

But if it gives them added confidence and peace of mind I can’t argue against it.

 

[Duke Dive Medicine]

I'm not aware of any published literature that has specifically addressed thyroid replacement therapy and risk of O2 toxicity. There's one article where researchers used hormone T3 to artificially increase oxygen metabolism in rat kidneys to induce renal hypoxia and kidney failure. Like a lot of animal literature, the dose administered to the rats was much higher than the recommended adult dose of levothyroxine (which is synthetic hormone T4, the inactive form of T3). Seizure is listed as a rare side effect of levothyroxine but that's not to say it would be synergistic with high inspired pO2.

<EDIT: A more definitive opinion from one of our attending physicians, paraphrased: if thyroid levels are within normal limits, then there's no difference between a diver who's on thyroid meds and a diver who isn't.> That is of course not a clearance to dive, it's a starting place for a conversation with the provider who follows you for this condition.

Best regards,
DDM

 

[rddvet]

I reached out to my doc and she didn’t have an answer for me

This is why having DAN insurance and access to their medical consult line is worth it. Most regular docs know little of how things relate to diving. We're lucky to have access to DukeDiveMedicine to answer questions, but a call to DAN is always a good choice.

 

[tursiops]

Let's see, who to believe?
Some random unknown uncited unlikely posts on social media

I’ve been seeing some conflicting posts etc about it being safe

Or a trusted, known voice of science and medicine....

I'm not aware of any published literature that has specifically addressed thyroid replacement therapy and risk of O2 toxicity.

<EDIT: A more definitive opinion from one of our attending physicians, paraphrased: if thyroid levels are within normal limits, then there's no difference between a diver who's on thyroid meds and a diver who isn't.>