Age

18–any

Sex

ALL

Healthy volunteers

Not accepted

Patient informed and not opposed to participating in the research
Age ≥ 18 years old
Severe chronic respiratory failure defined by PaO2 \<60 mmHg, whatever the cause, and justifying the initiation of long-term oxygen therapy
Not yet treated or with stopping oxygen therapy for at least 6 weeks
Be affiliated with a social security scheme or be a beneficiary of such a scheme
Be able to understand the interest and the constraints of the study

Exacerbation of respiratory failure in the 6 weeks prior to inclusion
Chronic kidney disease defined by a glomerular filtration rate (GFR) estimated by CKD-EPI \<60 mL / min / 1.73m2
Anemia at the time of inclusion whatever the cause (sickle cell anemia, thalassemia, hemolytic anemia, chronic iron deficiency, others)
Pregnancy
Breastfeeding women
Simultaneous participation in another therapeutic trial
Patient under guardianship or curatorship
Patient under medical help from the French government

Fibroblast Growth Factor 23 in Chronic Respiratory Failure