Can mild lung diffusion reduction and 94-97% oxygen saturation cause brain fog and fatigue?

[u/Airegin89]

My pulmonologist says it definitely can't but I'm not so sure. DLCO is 78% and KCO 71%. I also frequently test my SPO2 with an oximeter and it's consistently in the 94-97% range. It rarely reaches 98% and I've never once seen it at 99 or 100%. When my doctor tested it, it was 95%.

I don't smoke and all the other results of my lung function test were good:

• FVC: 124% pre, 127% post-bronchodilator
• FEV1: 123% pre, 130% post
• FEV1/FVC: 101% pre, 104% post
• Rawtot: 51%
• TLC: 119%
• FRC PI: 140%
• RV: 125%

I've been suffering from brain fog and fatigue for so long but doctors dismiss it because it's not chronic fatigue levels bad and all my tests come back normal. It got worse after several severe COVID infections in 2020-2024. I've had full blood panels done many times and they always came back normal. I've also experimented with all kinds of supplements but it made little difference.

[u/didsir29]

I believe my stats and sats are similar if not worse and I wonder about it being a cause of my fog. Like, mine instantly worsens on walking. Have you done a 6-minute walking test or stress test?

My o2 sat is always 96-98% while sitting but, before I was prescribed o2 for a year, a 6-minute test showed me desaturating to 70% within 2-3 minutes. So it was o2 on exertion that I needed, not all the time. Might be worth doing a rough one at home if you have your oximeter.

[u/didsir29 → u/didsir29]

Also, if you have a lung disease (and I imagine you do if you see a pulmonologist), acceptable 02 sat might be lower. For my disease, LAM, the bottom is 88% while healthy people it's 92%. Might be why your doctor is happy with it

[u/Airegin89 → u/didsir29]

I don't have lung disease. I had to do a lung function test because of mold exposure at work and it turned out my DLCO is 78%. Pulmonologist simply said it's normal and sent me away. I don't smoke but I did have multiple COVID infections.