Reid's Index is?

ANSWER: (A) Increased in Chronic BronchitisREF: Robbins 7th edition page 722, http://en.udkipedia.org/wiki/Reid_indexThe Reid Index is a mathematical relationship that exists in a human bronchus section observedunder the microscope. It is defined as ratio between the thickness of the submucosal mucussecreting glands and the thickness between the epithelium and cartilage that covers the bronchi.A normal Reid Index should be smaller than 0.4, the thickness of the wall always more than double the thickness of the glands it contains. Hyperplasia and hypertrophy of mucous glands as in chronic bronchitis causes them to be present at deeper levels in the bronchial wall and thicker in size, thus increasing the Reid Index beyond the normal value usually in proportion to severity and duration of disease.