Hey guys. I’m Siobhan, a 3rd-year medical resident. Today I’m gonna be telling you about Alex. Alex is a 28 year old man who works as an engineer and he’s never had any medical problems before. He’s known for always having a cup of coffee in his hand and he works really long hours. It was a regular Tuesday night. Alex finished work, went to the gym, came home, had some dinner and then by 10 o’clock he was getting ready for bed feeling tired, but normal. 5 hours later he woke up suddenly, unable to move his arms or legs. Alex was paralyzed! Alex was paralyzed. He couldn’t move his arms or his legs. He wasn’t in any pain and he could breathe normally. And other than this extreme sense of panic, he actually felt like himself. As fear flooded his body, Alex cried out for help and his roommate came in within a few seconds. After trying to lift him off the bed and failing, he called 911. At the emergency department Alex was quickly triage and then seen by the emergency doctor who asked him a lot of questions. Alex told her that this had never happened to him before or anyone else in his family. He doesn’t take any medications, he doesn’t use any recreational drugs. He doesn’t have any chest pain and shortness of breath or dizziness. He just couldn’t move his arms or his legs. The emergency physician examined him and found that he was tachycardic with a heart rate of around 110. His blood pressure was fine and he didn’t have a fever. On close examination of his muscles, she found that it was his proximal muscles: the ones closest to his core, that were weak. So his shoulders, elbows, hips and knees had 0 out of 5 strength. Meaning that when he tried to move them there wasn’t even a flicker of movement and the deep tendon reflexes weren’t present. But when she went to examine his wrists in his hands, he had 5 out of 5 strength, completely normal and luckily his sensation was completely intact. Okay, so we’ve got a previously healthy 28 year old man who’s presenting with acute onset paralysis of his proximal muscles. With such an unusual presentation and an unclear diagnosis, these are the moments we are weaned to step back and look broadly to consider all possible diagnoses so that we don’t miss anything. So what I always do is break things down into large categories, so that I can organize my thinking. So acute onset weakness: It can be a muscle problem, a nerve problem, a problem with the connection between the muscles and the nerves called a neuromuscular Junction or it could be an electrolyte abnormality. Now we need some more information to figure out which of these options is most likely. So the emergency physician ordered some bloodwork, an ECG to look at the electrical activity of the heart and a CT scan of the brain. The results are back and it’s shocking. Alex’s potassium is dangerously low at 1.6 mEQ per liter. It’s so abnormal that repeat bloodwork was sent right away, just to make sure it wasn’t a lab error, but sure enough it came back the same. So it looks like a slam-dunk, we have a cause for his paralysis. Such low levels of potassium is extremely concerning because it can cause a deadly heart rhythm. So the next step is to be replacing his potassium giving him some to drink, some through the IV and also giving him magnesium which helps with the absorption. So you’re probably getting the sense that potassium is pretty important, but I want you to understand how important potassium is in your body. It helps regulate fluid, muscle contractions including your heartbeat and being able to send signals down your nerves. And of all this potassium most of it, 98% of it is inside the cell. And the little bit that’s outside the cell inside the blood needs to be really tightly regulated, because too much or too little could be deadly. Your kidneys do a lot of the regulation, but there are also pumps on the outside of the cell membrane that help shift potassium in and one of those is called the sodium potassium ATPase pump. And on that note, Alex’s potassium is rechecked to make sure that it’s coming up into the normal range, but shockingly his potassium is still dangerously low. So there’s a trick in medicine: for every 10 mEQ of potassium you give someone, you expect their blood value to go up by 0.1. Now Alex received 360 mEQ of potassium, that’s a massive amount. Now you would expect his potassium to go from 1.6 all the way up to 5.2. But did that happen? No, it went from 1.6 to 1.9. Something is really not right. It’s not adding up, something else is going on. So we need to step back and try to figure this out. Alright, let’s break this down. Hypokalemia can be caused by not eating enough potassium, if somehow you’re losing potassium by either vomiting, diarrhea or if you have a condition that makes you pee out a whole bunch of potassium, if you have low magnesium or if your body is shifting potassium into the cells using that sodium potassium ATPase pump that we were talking about earlier. We really need to figure out which one of these processes is happening. Meanwhile an urgent blood work result comes back showing that Alex has high levels of thyroid hormone in its blood. This is really unexpected. This is called hyperthyroidism. So your thyroid is an organ just about here on your neck and it’s involved in regulating metabolism and affects almost every organ system in your body. When I think of hyperthyroidism I think of everything extra, so extra oil in your hair, extra nervous, extra tremor. You might be sweating more, your heart is racing, you’re having extra bowel movements, weight loss from high metabolism and you might actually feel hot all the time. With these test results the doctors went back to Alex and asked him about these specific symptoms. They found out that he actually had felt like he had a little bit of a tremor and sometimes he would feel like his heart was racing and he would always be wearing a t-shirt when other people were wearing sweaters. But he’d always thought this was just related to the amount of coffee that he was drinking all the time. 2 Hours later Alex started to move and then soon after that he was up and walking like everything was normal. So quickly his blood work was repeated. Potassium was completely normal and even his ECG changes had gone away, he just still had a bit of a fast heart rate. So this fits with the idea of an intracellular potassium shift. So all the supplements that were giving just kept shifting into the cells and in the blood the level was still low and just like that his level just normalized. So the question is: what is causing all this potassium to shift into the cells? Alright, back to the drawing board. And this is what medicine is all about, rethinking things if they don’t quite fit together. Okay, so major triggers for potassium to shift into cells. Well, Alex wasn’t taking any medications. Alkalosis and refeeding syndrome, we would have seen that on the blood work. Exercise, head injury, adrenaline, a heart attack. It just doesn’t fit with the story! And when he came in, he didn’t have hypothermia But this! Hypokalemic periodic paralysis, that sounds about right. And there is a sub type called thyrotoxic periodic paralysis. So this fit perfectly: thyrotoxic periodic paralysis. Alex came in with high thyroid levels and paralysis, it explains everything. So the question is: what is it? And how do we treat Alex? So to be honest, it’s a condition we don’t fully understand. We know it more typically happens to men of Asian descent who are in their 30s and it’s extremely rare. So all the people who have high thyroid in North America, only 0.1 to 0.2 percent of them will ever get periodic paralysis. Scientists have discovered that people with these conditions tend to have more of those sodium potassium pumps on the outside of their cells compared to the general population. So they’re more easily able to shift potassium into their cells and we also know some of the triggers: high thyroid levels, high carbohydrate meal which means high level of insulin in the body and then high intense exercise. So this makes sense, putting the pieces of Alex’s story together. So he was living with symptoms of hyperthyroidism, the fast heart rate and a bit of a tremor. He thought it was to do with coffee. Then on Tuesday night he exercised and he had a big carb load in his meal before going to sleep. While he was sleeping, potassium was shifted into his cells and he woke up paralyzed. So the good news is that by treating the underlying cause, the hyperthyroidism, we can prevent Alex from ever having these terrifying episodes of paralysis in the future. So he had some more testing done and he was diagnosed with Graves disease, which is one of the most common causes of hyperthyroidism and he was given treatment with 2 medications. The first one is called propranolol and that helps with the fast heart rate and the tremor. And the second one is called methimazole and that prevents him from making too much of the thyroid hormone. And I’m so happy to tell you guys that since treatment Alex had no other episodes of this and he’s been feeling so much better. So let’s just take a moment and realize how amazing our bodies are. Right now you’ve got thyroid hormone going through your body, your cells are shifting potassium in and out, your kidneys are fighting to keep the right amount of potassium in your body. It’s incredible! So anyway, I hope you guys enjoyed it. Let me know: had you ever even heard of periodic paralysis syndromes? Did you know what I was talking about already? I would love to hear! Anyway, don’t forget to subscribe and if you want to see more like this, I’ll be seeing you in the next video. So bye for now!