Effect of iron supplementation in women with chronic cough and iron deficiency.

Aims:  Chronic cough is more frequent and severe in women than in men. Women often have decreased iron stores, because of menses and pregnancies. We investigated if iron deficiency has a role in chronic cough by increasing airway sensitivity to inhaled irritants. Methods:  Twenty-two non-smoking women with chronic unexplained cough and iron deficiency (serum ferritin below 15 ng/ml) were examined in baseline, after 2 months empiric treatment with anti H1-histaminic drug and proton pump inhibitor, and after iron supplementation (330-660 mg iron sulphate tablets daily) for 2 months. Outcome measures were cough visual analogue scale (VAS), and histamine thresholds of the larynx (PC25MIF50, concentration causing 25% in MIF50), bronchi (PC20FEV1) and cough (PC5cough). Results:  Mean serum ferritin was 9.3 ng/ml (95% CI 7.7-10.9), 13 patients had mild anaemia. All the patients had laryngeal and cough hyperresponsiveness,12 had also bronchial hyperresponsiveness. Empiric treatment produced no significant effect, whereas iron supplementation improved cough VAS from 4.03 (3.6-4.47) to 2.6 (1.9-3.27), p < 0.0001, PC20FEV1 from 10.04 mg/ml (5.37-18.77) to 22.2 (11.7-41.8), p < 0.001, PC25MIF50 from 3.09 mg/ml (1.9-4.9) to 11.9 (7.3-19.4), p < 0.001 and PC5cough from 2.1 mg/ml (1.2-3.6) to 8.8 (5.2-15.1), p < 0.001. Conclusion:  In women with unexplained chronic cough unresponsive to targeted treatment, airway and cough hyperresponsiveness may be sustained by iron deficiency. Healthy women with chronic cough should be checked for iron deficiency as iron repletion may resolve such disturbing symptom.