Hemoglobin-oxygen equilibrium in cystic fibrosis.

A study of 35 patients with cystic fibrosis demonstrated that increasing severity 
of pulmonary involvement was associated with a mild but definite increase 
in erythrocyte 2,3-diphosphoglycerate (2,3- DPG) and a decrease in hemoglobin affinity 
for oxygen. The predominant regulators of 2,3-DPG were blood pH, cardiac 
output, and systemic oxygen transport. No significant relationship was observed between 
erythrocyte 2,3-DPG content and arterial oxygen tension. Hypophosphatemia may have prevented 
a greater increase in erythrocyte 2,3-DPG content. The inadequate increase in 
2,3-DPG and consequent insufficient change in hemoglobin-oxygen affinity, coupled with an 
insufficient compensatory erythrocytic response, may adversely affect tissue oxygenation in patients 
with severe cystic fibrosis. 