Why can sunlight exposure induce sneezing?Achoo! Ever thought about why you sneezed when you stepped into sunlight? Well, this same question plagued even Aristotle himself, so much so that in The Book of Problems, he asked, “Why is it that one sneezes more after one has looked at the Sun?” His answer was that sneezing resulted from a chain of physical events in which the sun heated the nose, eventually triggering a person to sneeze. But, as you can probably guess, the story is a bit mor...

Why don’t interstitial lung disease patients typically get increased pCO2?Early on in medical training, you learn to separate a patient’s oxygen from their carbon dioxide. A COPD patient can be heard wheezing from across the ward with a pCO2 of 80mmHg and actually have a stable O2 saturation, while their neighbor with interstitial lung disease will be barely maintaining their oxygen on six liters and have a pCO2 of 40mmHg. The thinking, simply put, is that O2 is about air “in” and pCO2 ...

Why does an autoimmune antibody stimulate the thyroid in Graves’ disease?When we think of antibodies, such as monoclonal antibodies that target specific diseases, we often think of them as blocking receptor-ligand interactions or binding to pathogens to neutralize them. Yet in Graves’ disease, we actually find the opposite of what we would normally expect: an antibody actually activates the receptor rather than inhibit it.

Why do patients with active lupus have a low CRP?Although the erythrocyte sedimentation rate (ESR) is typically high in active lupus, C-reactive protein (CRP) is often normal. What’s particularly cool about this finding is that it lends insights into the mechanism of lupus and potentially its cause.The earliest report alluding to this discordance was published in 1951 by Alan Hill. He wondered whether CRP could be used to track disease activity in various non-infectious inflammatory con...

Why doesn’t factor 12 deficiency cause bleeding?In July 1953, freight brakeman John Hageman’s doctors faced a scenario that might feel familiar to anyone who has ever done preoperative medicine consults. Hageman had planned to undergo a partial gastrectomy for peptic ulcer disease, but his preoperative tests showed a prolonged clotting time. In the 1950s, we knew about other diseases with prolonged clotting times; hemophilia in particular, which at the time referred to what we now know ...

Why can’t people with familial fatal insomnia fall asleep?Have you ever wondered why you feel so awful when you don’t get enough sleep? Well, that’s because it is no exaggeration when we say we need sleep to survive, so much so that we spend approximately ? of our lives sleeping. Insomnia can certainly feel exhausting, overwhelming, and even lonely – while everyone is asleep, there you are – wide awake and unable to fall asleep no matter how much you try. Except, now imagine that other ...

Why does cirrhosis cause high SAAG ascites?Other than when there’s Thai food at noon conference, it’s the best part of the day on inpatient medicine. A patient comes in with ascites, they get a diagnostic paracentesis, you look at the fluid albumin and subtract it from that serum albumin that you pray you remembered to order before the tap. This is the serum ascites-albumin gap (SAAG). You google that chart that you’ve somehow never remembered to bookmark, and, unlike most other lab val...

How does a bacterial species called Deinococcus radiodurans withstand extreme levels of radiation?What comes to mind when we say tiny but mighty? Well, if Deinococcus radiodurans didn’t cross your mind, maybe it will earn your respect after this segment, so much so that it may come to mind the next time someone asks you that question. In our previous episode, “Wherefore Iodine?”, we learned about why iodine administration was a key public health intervention in Eastern Europe followin...

Why does valproic acid cause elevated ammonia?Ah, serum ammonia. A lab that is often sent and often a head-scratcher. Sometimes an altered patient with cirrhosis and the most textbook asterixis will have a normal serum ammonia. And other times a patient has a sky-high ammonia and you have no idea why. Have you ever stopped and checked if they’re on valproic acid?

What’s with the black mold growing inside Chernobyl?In recent Curious Clinicians episode about the tragedy of Chernobyl and the public-health effort to distribute iodine pills to the victims, we mentioned that the reactor that exploded (and even some of the wider fallout area) is now host to a curious organism: A black fungus that apparently eats radiation. How does radiation, which usually kills living things, end up sustaining something?