WILTIMS #432-434: Untz untz untz... oh, not that kind of clubbing

MondayIL: Homans sign is a physical exam maneuver used to test for deep vein thrombosis (DVT). To perform it, you have the patient rest on their back while you support their knee. You then abruptly flex their ankle. If this elicits discomfort, it is positive for... actually probably nothing. This sign is a terrible predictor of DVT and may even be dangerous to perform. Don't use this test.

Every once in a while I learn something that I realize I should have learned ages ago. Unfortunately I usually learn these facts in an awkwardly public setting like in front of attending or patient. Today's example is about clubbing. Clubbing is when the tips of one's fingers swell and the fingernails curve (making the fingers look like little clubs, hence "clubbing"). I therefore thought that dramatically curved fingernails were indicative of early-stage clubbing. Nope. Not a thing. People can just have curved nails.

The way you actually tell if there is clubbing is by looking at the angle made by the tip of the nail, the root of the nail and the first knuckle. If it is concave, it's normal. If it's flat then there is mild clubbing. If its convex (the nail bed bends out between the knuckle and nail tip) then there is severe clubbing. We still don't know what causes clubbing, just that it is correlated with a whole bunch of serious disease processes.

TuesdayIL: Gadolinium contrast (the stuff used in MRIs to make body-stuff more visible) is cleared from the blood much more slowly in patients with chronic kidney disease. This can cause nephrogenic systemic fibrosis, a disease that sounds really vague, but is actually only caused by gadolinium exposure.

Autosomal dominant polycystic kidney disease (ADPKD) is caused by a defective APOL1 gene. This allele is very prevalent in the black population, much like the sickle cell allele, and it's thought that this parallel is due to a similar reasons. Whereas sickle cell heterozygotes (people who only have one copy of the defective gene) are thought to be protected from malaria, APOL1 seems to protect from a different parasitic disease called trypanosomiasis.

We have no good treatment for ADPKD. We can essentially use dialysis to bide time until a kidney transplant can be done. An interesting issue can arise when a family member wants to donate a kidney. Since the disease is inherited, there is a not-insignificant chance that the family member also has ADPKD and will need their extra kidney for as long as it is healthy. So to attempt to donate, the family member needs to consent to finding out that not only can they no donate, but that they may be soon heading for the same fate.

WednesdayIL: Dementia can cause increased variations in an elderly patient's sleep cycle. There are normal age-related changes, such as going to bed earlier, waking up earlier, sleeping lighter, waking up more often, etc. Patients with dementia frequently have worse sleep disturbances including a shift away from the restful REM sleep.