Correlation of Iron Levels with Asthma and Lung Function in Pediatric Patients with Sickle Cell Anemia

Introduction:Significant morbidity and mortality in patients with sickle cell disease (SCD) is attributed to the pulmonary sequalae of the disease. Patients with SCD often suffer airway hyper-reactivity, acute chest syndrome (ACS), chronic lung disease, pulmonary hypertension (PHTN), and obstructive sleep apnea (OSA). Recent literature has provided evidence supporting the strong association between asthma and airway hyper-reactivity in SCD. One of the factors linked to chronic inflammation and asthma is iron status. The present study examined whether iron levels are associated with pulmonary complications in pediatric patients with SCD.

Method:Through retrospective review of electronic medical records (EMR) we evaluated patients with diagnosis of asthma and SCD. All patients with available PFT (3/21/2013-3/11/2020) and iron studies were included in the analysis. Chi square and ANOVA tests were used to explore relationships of respiratory conditions with lab data and relevant medical history.

Results:The analysis reviewed information of 100 patients with SCD -- 56 males and 44 females The sample population had the following genotypes: 63% Hemoglobin (Hb) SS, 23% Hb SC, 2% Hb S Beta Zero Thalassemia, and 12% Hb S Beta Thalassemia. 38% of these patients were receiving treatment via hydroxyurea. The results generated found that patients with a large airway obstruction (LAO) had a marginally statistically significantly higher serum iron level than those with no LAO (p=0.067.) Patients with homozygous Hb S disease were four times as likely to have a history of ACS (p=0.004) than those without and were marginally significantly more likely to be SS and SB0Thal (p=0.052). Patients with history of ACS had a significantly higher mean iron saturation and lower total iron binding capacity (TIBC.) Patients with PHTN had significantly higher serum iron levels (p=0.029).

Conclusion:Our findings reveal that while iron might play a more significant role in the development of PHTN and ACS in patients with SCD, the role in asthma is borderline in our sample. These findings, although of borderline statistical significance p=0.067, are clinically noteworthy. These results may open a new window for therapy targeted at maintaining iron in normal physiologic ranges to decrease pulmonary complications in patients with sickle cell anemia. Further studies with larger samples are necessary to clarify the meaning of our marginally significant findings.