I commented on these labs in your other thread.
Low PaO2 is called hypoxemia (low blood oxygen). The bone marrow may be stimulated to produce excessive red blood cells (RBC) in cases of chronic hypoxemia.
From the Mayo Clinic article "Hypoxemia (low blood oxygen)"..
"Common causes of hypoxemia include:
ARDS (acute respiratory distress syndrome)
Certain medications, such as narcotics and anesthetics, which depress breathing
Congenital heart disease — heart defects that are present at birth
COPD (chronic obstructive pulmonary disease)
Interstitial lung disease
What symptoms are you having?
I'm not sure about the other tests but your Free T4 (FT4) is BELOW range and your Free T3 (FT3) is below mid range.
many people have found that in order to feel well they need their FT4 to be MIDDLE of the range if not a bit higher AND (that means in addition to) their FT3 to be in the UPPER 1/3 of the range.
Thus if you are feeling hypo (low) thyroid symptoms I would not be surprised because you are below those levels. Some people feel fine with your numbers but many don't.
TSH is a screening tool at best and is not that reliable. But it also would indicate borderline hypo as the American Academy of Clinical Endocrinologists (AACE) recommends a reference range or (0.3 - 3.0) your result of 2.7 is towards the upper part of that range for what it's worth.
Vitamin D is also very low.
Many people find that they need to be towards the upper end of the ranges for both Vit D as well as Vit B-12.