Clubbing (not the booty-shaking kind)
Time for a brief medical post, since life goes on and I might as well be learning something. (This post is FULL of jargon because it’s aimed at those with at least a smidgen of medical vocabulary.)
Clubbing is one of those physical findings that we always are expected to comment on in physical exams, especially in a test situation. I remember diligently commenting “no clubbing, peripheral cyanosis, or pedal edema” standardly on every darn cardiac and respiratory OSCE (Objective Structured Clinical Exam aka mock patient scenario) station I’ve ever been through, so as to get some free tick-marks on my evaluation.
Clubbing has always been this mysterious thing – I’ve probably seen the real deal once in my life. As seen on House, clubbing is not stubbiness of the fingers. It consists of three findings which must all be present: a specific change in Lovibond’s angle, the angle at which the nail joins the nailbed, to an obtuse degree; a widening of the nail; and a sponginess of the base of the nailbed. In order to be legitimate, one ought to check both the hands and the feet for these changes. Shamelessly borrowed from the Merck manual:
These changes are accompanied by periosteal thickening, which can be elucidated on an x-ray of the wrist. The pathophysiology is not that well understood, but the University of Leeds’ Professor David Bonthron has undertaken research suggesting that it is secondary to an accumulation of prostaglandin E-2 (PGE-2),
‘We knew that in cystic fibrosis patients who have undergone a lung transplant, their finger clubbing goes away. The same goes for empyema patients who have had the [abscess in their] lungs drained’. . .
Their findings implicated a fatty compound called PGE2, which is produced naturally by the body to mediate the effects of internal inflammation. Crucially, once it has done its work, PGE2 is broken down by an enzyme 15-HPGD, produced in the lungs. The patients followed by the Leeds study were found to have a genetic mutation which prevented the production of 15-HPGD, resulting in up to ten times as much of the PGE2 in their systems.
‘If you don’t have this enzyme the PGE2 isn’t broken down normally and simply builds up,’ said Bonthron. In lung cancer patients, it is most likely overproduction of PGE2 by the tumour that causes the clubbing. In congenital heart disease, blood bypasses the lungs, where PGE2 is normally broken down by 15-HPGD.
Though there are a plethora of diseases thought to cause this finding, there are really only four common causes in practice.
– Pulmonary Fibrosis
– Bronchogenic Carcinoma
– Cyanotic Congenital Heart Disease (CHD)
– Subclinical Suppurative Infective Endocarditis / any chronic septic state
For the keen among you:
My preceptor today told a story of one of his past examination scenarios. He had 45 minutes in which to perform a history and physical on a patient, with the examination objective being simply a diagnosis. He walked into a room and introduced himself to the patient. The patient, on oxygen by nasal prongs, kindly informed him “don’t worry doc, it’s not cancer!” My preceptor proceeded to take a quick look at the patient, ready to examine him. He immediately noticed clubbing, and in the three minutes the “hello” and quick inspection took, he was finished the exam.
Likely a lung problem, as evinced by the oxygen use (though in cases of cyanotic CHD, I suppose someone could be on O2). It wasn’t a cancer, as per the patient’s report. What was left? Only one diagnosis.: Pulmonary Fibrosis. Easy peesy. He had a pleasant conversation about current affairs with the patient for the remaining 42 minutes.
Okay, that’s a nice story, but it can be more complicated. A person could be on oxygen for some other condition and have clubbing secondary to a more weird and wonderful diagnosis. But simple things being, well, simple, it was a pretty decent algorithm.
The point is, if you see clubbing, great – it might help narrow your differential. Just know what you are looking at and why it might be present. Especially if you will get ‘pimped’* by your preceptor about it!
* the ancient are of ‘pimping’ in medicine deserves a post unto iteself