Assessment of iron status in cystic fibrosis patients

We investigated the use of soluble transferrin receptor (sTfR), together wi th mon traditional measurements such as iron, transferrin and ferritin, to assess iron status in 70 adult cystic fibrosis patients. sTfR concentration was measured using particle-enhanced immunoneghelometry. We found that 69% of subjects as determined by transferrin saturation had iron deficiency, b ut only 29% as determined by sTfR and 11% as determined by ferritin. We fou nd a significant correlation between C-reactive protein (CRP) and both ferr itin (r = 0.38, P=0.0001) and transferrin saturation (r = -0.54, P<0.0001). In addition, because the CRP concentration was elevated in 64% of subjects , we reel that the transferrin saturation was overestimating, and the ferri tin underestimating, iron deficiency in these patients. The sTfR concentrat ion. on the other hand, is unaffected by the acute-phase response and was t herefore thought to be the most useful test for detecting iron deficiency i n this group of patients.