Science Fact - The Sweet Smell of Liver Failure

I just started a 2 week medical elective in my home province of Nova Scotia. I've been away for so long that I thought I could easily deal with living abroad (read: Ontario) without feeling like I'm missing out on the Maritimes. But now that I'm here I feel like I have been trapped in the Maritime tractor beam and am being slowly pulled back to my heritage. Or at least one of my heritages. The strange thing is that I became most drawn toward Nova Scotia again because of the smell of Downtown Halifax. It's not necessarily the cleanest smell, as the famous Halifax harbour contributes to the overall scent, but it's intriguing nonetheless. It smells like home to me.

Speaking of smells, I had an interesting encounter today in clinic. I am learning about liver disease and liver failure from one of the leading hepatologists in the Maritimes, and we were assessing patients to see if they qualified to get a brand new (or technically second-hand) liver. In the middle of one assessment, my preceptor casually told me to smell the breath of the patient.

Now I don't know what the proper etiquette is on assessing the odour of a patient's breath. Do you ask them to blow in your face? Do you use 2 fingers to waft their breath toward your nose, like smelling a fine wine or a dangerous chemical? Do you put your nose a few inches away from their face? After you smell their breath, do you nod approvingly or keep stone-faced throughout it? So many questions...

The interesting thing was that I could smell something peculiar. Something I had smelled in the hospital before with very sick patients. It's difficult to pinpoint that exact smell, but the closest description would be sweet, flowery feces. It sounds gross, and it really is, but that only dawns on you after a few whiffs. At first you think to yourself "What is that smell? Is it good or bad? Where is it coming from?" Once you get the words "sweet shit" in your mind, it's hard to feel the same curious enjoyment from the smell coming out of someone's mouth.

The technical term for this aromatic breath is fetor hepaticus, otherwise known as the breath of the dead. It's caused by liver disease that is progressing or has already reached the status of liver failure. In fact, it's the most sensitive sign of liver failure out of all the possible signs (such as spider nevi, gynecomastia, ascites).

Here's the science behind the unique smell. The liver is a major organ that's responsible for several things. (1) It detoxifies the blood, metabolizes drugs and removes harmful compounds. (2) It can store glucose in a handy easy-to-use molecule called glycogen. (3) It helps your blood to clot by making hormones that promote the production of platelets, and by making vitamin K which promotes the production of clotting factors. (4) It makes albumin, a very common yet important protein that holds fluid in your blood vessels and helps to transport molecules throughout the bloodstream.

The breath of the dead has to do with the first reason (detoxification). In people with liver disease for some reason or another, they can develop cirrhosis. Cirrhosis of the liver means that the liver has been damaged, and instead of being replaced by normal liver cells it gets filled in by fibrotic tissue. The tough, structural, and nonfunctioning fibrotic tissue "takes over" the liver, so that the overall liver function is greatly reduced. All of your blood passes through your liver in the "portal system", but if your liver is tough and fibrotic can't filter the blood very well. This causes the blood to back up. After a while, the blood gets pissed off and tries to find other ways around the liver to complete the circuit back to the heart. The blood travels through smaller veins that pass along the esophagus, and then end up in the heart and lungs. But by bypassing the liver, the blood is now full of toxins and weird chemicals. Some of these chemicals are aromatic so they get excreted into your lungs, and you breath them out. Thus, the strange smell. It's sensitive for liver disease because only people with bad livers who have developed alternative blood pathways will get this.

The bad news is that these toxins can enter your brain and cause may problems. This is known as encephalopathy. Many people who develop encephalopathy (without proper treatment) have a poor prognosis and will die rather quickly. That's why that smell is known as the breath of the dead.

So the next time you smell sweet excrement, think fetor hepaticus.