CHICAGO - INSTEAD of cough drops, some women may need to reach for an iron supplement to treat that pesky cough, Italian researchers said on Tuesday.

The study, presented at the scientific meeting of the American College of Chest Physicians in Chicago, suggests iron deficiency may help explain why some otherwise healthy, non-smoking women had persistent coughs.

Tests on women with chronic coughs and iron deficiency showed that a simple iron supplement often cleared up the cough, said Dr Caterina Bucca of the University of Turin and colleagues.

Dr Bucca said women also are more likely than men to suffer from otherwise unexplained chronic coughs.

'We put the two together,' Dr Bucca said in a telephone interview. 'Cough is much more frequent in women and iron deficiency is very frequent in women due to pregnancy and menses.' In addition, immune function can be affected by iron deficiency, which is defined as having low iron levels, sometimes to the point of anaemia.

Dr Bucca and colleagues studied 16 women with chronic cough who were found to have normal lung function, with no signs of asthma or other respiratory disease and no evidence of acid stomach reflux that could explain their coughing.

All had iron deficiencies.

And they all had signs of swelling in the back of the mouth and red, inflamed mucous membranes. Their vocal cords were also very sensitive, making them cough and choke easily, such as after vigorous laughing.

Dr Bucca gave these women iron supplements to improve their iron stores. When these had normalised - after about two months - they were checked again.

After iron supplementation, coughing and signs of inflammation in the mouth and vocal cords were improved or completely resolved.

'I found the hypersensitivity was nearly gone or vastly improved in all of the women,' Dr Bucca said.

Because iron helps regulate the production of proteins in the immune system that control inflammation, an iron deficiency might make the upper airway more prone to inflammation, leading to this chronic cough, she reasoned.

She plans to study this association further, but she urges doctors who are stumped by women patients with chronic coughs to check for iron deficiency. -- REUTERS