Which Reid index threshold is diagnostic for chronic bronchitis?

Which Reid index threshold is diagnostic for chronic bronchitis?

• A. Reid index > 0.6
• B. Reid index > 0.3
• C. Reid index > 0.4
• D. Reid index > 0.2

Answer: (C)

The Reid index is a measure of mucous gland prominence in the large airways, calculated as the thickness of the mucous gland layer divided by the thickness of the bronchial wall (from the epithelium to the cartilage). In healthy airways this ratio is about 0.4. In chronic bronchitis, mucous glands undergo hyperplasia and enlarge, pushing the ratio higher. Because this change reflects the glandular remodeling characteristic of chronic bronchitis, a Reid index greater than about 0.4 is used as a diagnostic threshold. Among the given options, this threshold best matches the diagnosis criterion. Values like 0.6 would indicate more extreme gland enlargement, while 0.3 or 0.2 stay below the normal range and do not indicate chronic bronchitis.

The Reid index is a measure of mucous gland prominence in the large airways, calculated as the thickness of the mucous gland layer divided by the thickness of the bronchial wall (from the epithelium to the cartilage). In healthy airways this ratio is about 0.4. In chronic bronchitis, mucous glands undergo hyperplasia and enlarge, pushing the ratio higher. Because this change reflects the glandular remodeling characteristic of chronic bronchitis, a Reid index greater than about 0.4 is used as a diagnostic threshold. Among the given options, this threshold best matches the diagnosis criterion. Values like 0.6 would indicate more extreme gland enlargement, while 0.3 or 0.2 stay below the normal range and do not indicate chronic bronchitis.