Hank:

[Breathes onto screen]

Do I smell okay to you?
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When it comes to diagnosing health problems, there's actually a lot that we can learn about our bodies without fancy equipment.  And I'm not just talking about whether you have a fever or where your 'owwie' is.  The fact is, we're constantly giving off all kinds of chemical signals that reveal what's going on inside of our bodies.  These signals are often volatile, organic compounds; carbon-based chemicals produced by various organs that evaporate easily, so they show up a lot on our breath, on our skin, in our urine, and in pretty much everything that comes out of us.  They also tend to stink, ammonia and acetone, also known as nail polish remover, are good examples.  In fact, you're excreting them both right now!  But don't worry about it, you smell fine!  Seriously, I promise.  But it is possible to make some diagnosis by detecting these and other compounds.  And here is one way of doing it: dogs.  A dog's sense of smell is about a million times more sensitive than humans, so dogs can be used to detect certain kinds of cancer, like bladder, colon, and even lung cancer.  Tumors produce their own signature volatile compounds and dogs trained to pick up on these traces actually detect tumors at much earlier stages than a lot of the fancy, cancer finding tests we've got these days.  They are also a lot less invasive than a lot of the cancer that we have these days, because I've had some of those and I would much rather be sniffed by a dog.  Now the medical establishment has only started to come around to using dogs as diagnostic tools, but people can smell too, right?  Breath odor, the odor of one's breath has long been known to be a key indicator of illness.  A fruity odor on someone's breath might indicate that they've been enjoying a stick of Juicy Fruit gum, or that their body is trying to get rid of excess acetone, which could be a sign of their developing diabetes.  Breath that smells like poop can be a signal of bowel obstruction, for obvious reasons.  And if your breath smells like ammonia, that could be a sign that you have chronic kidney failure.  A lot of doctors aren't super into sniffing their patients' breath, for some obvious reasons, but they are willing to invent some machines to do it for them.  In the past few years, researchers have looked into using chemical analyzers, like this olfactometer, and variations on this thing called the electronic nose to diagnose patients' smells.  But let's not forget your pee.  The smell of urine can contain chemical traces of bladder cancer, but it can also reveal a lot about your metabolism.  Excessively sweet smelling urine is actually the leading indicator for a potentially fatal condition called "maple syrup urine disease," an inherited condition that makes the body unable to process certain amino acids.  As the name says, it makes your pee smell like Mrs. Butterworth's, which would be totally awesome, except for the part where it might kill you.  And then, there's another way that people used to make diagnosis with urine.  In 1674, English physician Thomas Willis discovered that the urine of a diabetic tasted quote: "Wonderfully sweet, as if it were imbued with honey or sugar."  Indeed, for thousands of years physicians have been tasting patients' pee to help diagnose diabetes.  Since diabetes inhibits the body's ability to break down sugar, diabetics have high levels of sugar in their urine, and you know, what else are you gonna do?  In fact this is why to this day, the clinical names for both kinds of diabetes--Diabetes mellitus and Diabetes insipidus--actually refer to the taste of the patient's urine.  Mellitus, being Greek for honey or sweet, and insipidus, meaning flavorless.  Wow, that didn't make me feel any better.  But hopefully you learned something.  Thank you for watching this episode of SciShow.  if you have questions or suggestions, leave them in the comments below, or on Facebook or Twitter and we will see you soon.

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