My recent PFT also showed low DLCO, 49. Same as yours...how ironic. I’m seeing a new Pulmonologist at the end of the month, but I’ve been trying to do some research in advance. I found one study showing DLCO could/should be measured in POTS patients both supine and upright. Considering our tendency towards low blood volume and blood pooling, it makes since to me. I understand there are many reasons for low diffusion rates; however, I’ve not found many reasons/ treatments for SOB in POTS. I just wanted to touch base, and let you know there one more of us out there. Have you discovered anything new about your condition?