Iron Deficiency Common Among CF Patients and Requires Routine Screening and Guidelines, Study Suggests

Iron deficiency is common among adults with stable cystic fibrosis (CF) and is significantly associated with anemia, vitamin A deficiency, antacids use, and moderate to severe lung disease, a study shows.

Prevalence rates of iron deficiency were found to vary widely due to poor agreement between several laboratory indicators of iron status. Thus, researchers recommended that guidelines be developed for routine and standardized screening, as well as for diagnosis and management of iron deficiency in CF patients.

The study, “Prevalence and Risk Factors for Iron Deficiency in Adults With Cystic Fibrosis,” was published in the journal Nutrition in Clinical Practice.

Iron is a micronutrient involved in several important biologic processes, but is mainly associated with the production of hemoglobin, the oxygen-transporting protein present in red blood cells.

Iron deficiency is the main cause of anemia (low levels of red blood cells or hemoglobin), which is then classified as iron-deficiency anemia. Anemia can lead to weakness, shortness of breath, heart problems, and increased risk of infections.

Several studies have estimated that 28%–69% of CF patients have iron deficiency, a higher frequency than estimates for the general U.S. population. However, the lack of standardized values to classify iron deficiency, and the fact that many of these studies assessed iron levels regardless of CF patients’ disease state — which is known to influence iron values — challenges the interpretation and generalization of these data.

In addition, “despite a seemingly high prevalence rate, few centers are routinely screening for iron deficiency, and there are presently no guidelines on screening, diagnosis, or management of iron deficiency specific to the CF population,” the researchers wrote.

Thus, a team of researchers at the University of Virginia Health System set out to identify the frequency of iron deficiency and anemia in adults with stable CF, and the risk factors associated with both conditions. They also compared iron deficiency occurrence rates using different cutoff values for commonly used laboratory indicators of iron status.

The researchers retrospectively analyzed the clinical data of 105 people with stable CF (54 men and 51 women), followed at their medical center. The mean average age of the patients was 34.7 years, and 67 of them had iron status data.

Iron deficiency was defined as less than 12 ng/mL of blood ferritin, and/or less than 16% of transferrin saturation (the potential capacity of transferrin to bind to blood iron). Of note, ferritin is a protein mainly used to store iron in the body, and transferrin is an iron-transport protein that controls the levels of free iron in biological fluids.

Anemia was defined as hemoglobin levels lower than 12 g/dL for women, and lower than 14 g/dL for men. Comparison of common laboratory indicators of iron status included the blood levels of iron, ferritin, transferrin, and the percentage of transferrin saturation.

Results showed that 41.8% of these stable CF patients had iron deficiency, while 33% had anemia. Iron deficiency was more commonly found in women (51%) than in men (30%) with CF.

“These analyses reveal that iron deficiency and anemia are widespread across the adult CF population, even under stable conditions without the influence of acute illness affecting laboratory results,” the researchers wrote.

Iron deficiency was significantly associated with anemia, vitamin A deficiency, and antacid use, as well as moderate and severe lung disease, when compared with mild lung disease.

In turn, anemia was found to be significantly associated with vitamin A deficiency, severe lung disease, low body weight, diabetes, and bone disease. These factors are generally linked to CF severity, which suggests that “anemia may simply be another complication of worsening [CF] disease,” the researchers wrote.

“It would be advisable for CF care centers to begin routine assessment of iron status, especially in patients with the aforementioned characteristics,” they added. Moreover, the frequency of iron deficiency in these patients varied widely, depending on the markers and cutoffs values used, highlighting the importance of using multiple laboratory indicators to assess iron deficiency.

“Iron-deficiency prevalence rates can range from 9.7% to 87.1% in this population, depending on which iron laboratory marker and cutoff was chosen,” the team noted.