This post has been written in response to the comment on this article.
The original question was
I am one of medical student in ETHIOPIAN university and I am confused how clubbing is happen? i.e the pathophysiology of clubbing.
Widely speaking the specific mechanism of digital clubbing is still not known.
Increased interstitial edema is the earliest change. As clubbing progresses, the volume of the terminal portion of the digit may increase because of an increase in the vascular connective tissue and change in quality of the tissue.
It is postulated that different pathological diseases may cause different pathways to a common end point.
Most researchers agree that this results from an increase in distal digital vasodilation is the major factor. But what causes the vasodilation remains unclear. Also unknown is the exact mechanism by which increased blood flow results in changes in the vascular connective tissue under the nail bed. A circulating or local vasodilator, neural mechanism, response to hypoxemia, genetic predisposition, or a combination of these are thought as possible factors/
An increased incidence of digital clubbing has been associated with the vagally innervated organs and therefore a neural mechanism has also been purposed.
Genetic inheritance and predisposition has also been proposed.
Recent studies have suggested platelet-derived growth factor as the possible mediator of the digital clubbing. This factor has been shown to have general growth-promoting activity and causes increased capillary permeability and connective tissue hypertrophy.