Hypothyroid Pathophysiology and Symptoms (Plus the MUST-KNOW Critical Thinking Points!)

Hey there friend. My name is Christina Rafano from nursingsos.com and today in this video we are walking through the pathophysiology and the signs and symptoms of hypothyroidism or underactive thyroid. And we'll also cover the must know critical thinking points that you'll need to know about it to pass your nursing school exams. So hit that subscribe button and click the notification bell and let's dive in. So there's a little part of the brain called the hypothalamus and his job is to release a hormone called called thyrotropin releasing hormone or trh. Now TRH is going to travel down to the anterior pituitary gland and tell the ap, the anterior pituitary to release thyroid stimulating hormone or tsh. Now these are two different hormones, trh, thyroid releasing hormone and tsh, thyroid stimulating hormone. I like to remember, here's a memory trick for you that R comes before S in the Alphabet and that the hormone needs to be released in before it can then stimulate something. So those are two good ways to remember that. So now TSH is going to travel down to the thyroid gland and the thyroid gland is going to release the active thyroid hormones. And These are called T3 and T4. These are the actual thyroid hormones that cause all the changes in the body. TRH and TSH just help T3 and T4 to be released. But T3 and T4 are really the active thyroid hormones. Now here's a fun memory trick to help you remember T3 and T4. I like to think 3, 4, let's go. 3, 4, let's go. Almost like a team huddle before a football game. I know it helps me, but we will see in a minute the T3 and T4. Those active thyroid hormones play a key role in the body's metabolism. So when T3 and T4 are increased, the metabolism is revved up and it's ready to go. So think to yourself, three, four, let's go. Because the metabolism is ready to go. And once T3 and T4 are released and the body gets enough of them, it tells the hypothalamus and the anterior pituitary gland. I'm good, thanks. And the hypothalamus then stops releasing TRH and the anterior pituitary stops releasing that tsh. So that's a feedback loop. So during hypothyroidism there is too little T3 and T4. So there aren't enough of those thyroid hormones. The most common causes of this are a lack of Iodine and Hashimoto's thyroiditis, which is an autoimmune disorder. Iodine is necessary to make thyroid hormone, so without it there is a lack of thyroid hormone. And during Hashimoto's thyroiditis, the body's immune system is actually attacking the thyroid gland so it can't function properly to make thyroid hormone. Now, it's important to note that both of these are causes are primary causes of hypothyroidism, meaning that something is wrong with the thyroid gland itself. There are other causes of hypothyroidism that are secondary causes, meaning that there is something wrong somewhere else in the body. And the thyroid gland isn't getting that TRH or TSH that it needs to tell it to make those T3 and T4 thyroid hormones. But these two primary causes that lack of iodine and Hashimoto's thyroiditis, these are the most common. So we're going to focus on them, especially when you're studying for the nclex. So in each of these cases, both a lack of iodine and Hashimoto's thyroiditis is there isn't enough T3 and T4, which are those active thyroid hormones. And without enough T3 and T4 in the body, the brain sees that and wants to increase TRH and TSH so that the thyroid can be stimulated to make more T3 and T4. But even when the brain gives more TRH and TSH, the thyroid gland can't make any more T3 or T4. So what will happen is that that TRH and TSH, those levels will rise in the body while T3 and T4 drop. This is a key critical thinking point for you to know. In hypothyroidism, the TSH will be high, but T3 and T4 will be low. Think of T3 and T4 as opposites or enemies of TSH. They are not friends, they don't like each other. They should be friends and normally they are. But here in hypothyroidism they have a conflict with each other. They are not happy, they are fighting. So when the TSH level is high, when TSH shows up for a party, T3 and T4, they don't want to be there, so those will be low. So let's put this process into some simple steps for you to follow. You know that I always like giving you step by step processes to help you learn all of this faster and easier. So step number one happens when the thyroid gland can't produce T4 or T3. Typically because of A lack of iodine and Hashimoto's thyroiditis. Now, step two is when the brain sees those low T3 or T4 levels and it wants to help. So it increases the TRH and TSH levels to try to stimulate the thyroid gland to produce that T3 and T4. And finally, step number three, the TRH and TSH levels rise in the body while the T4 and T3 levels drop. Because if TSH shows up for the party, remember T3 and T4 don't want to come. So this is one of our key critical thinking points here. When there's not enough thyroid hormone, the body's metabolism slows down and all of those processes are going to slow down as well. So now that we understand that, let's walk through some of the signs and symptoms of hypothyroidism. I'll also call out the key ones that you definitely, definitely want to remember for the nclex, because there's certain ones that the NCLEX just loves to test you on. We're going to cover a lot right now, so I also wanted to make sure that you know that you can get my full hypothyroid study guide inside the nursing SOS membership community. I'll put a link to that down below in the description. That way you can print out the study guide inside the NMC and use it while you study, which will help make things way more easier for you. So some of the common signs and symptoms of hypothyroidism that you might see are fatigue, weakness, memory loss, feeling cold, or an intolerance to cold, decreased respiratory rate and a decreased heart rate, dry skin, hair loss, edema, weight gain, constipation, and changes in menstruation. Now, the patient might have a goiter, might not have a goiter. So that first set of signs and symptoms are kind of those neurological ones. Fatigue, weakness and memory loss. So with hypothyroidism, the whole body is slowing down. All of the internal body processes are slower than normal. This is our key critical thinking point. Remember, when there's not enough thyroid hormone, the metabolism is worse. Oh, slow down. This can cause the brain to respond slower than normal, and that's how you end up with these neurological changes, things like fatigue and weakness and memory loss. The patient may also feel cold and be what we call cold intolerant. So they don't like the cold. Now, this is a big NCLEX key point, intolerance to cold. It's a big symptom for hypothyroidism that's because all of the processes in the body are so slower, and this can cause the body temperature to decrease somewhat, causing them to be cold. So all of those metabolic processes that are always happening in the body, those are what keep the body warm and cozy. So when the metabolism is slowed down, the temperature can decrease and they can have cold intolerance. And the NCLEX loves to test on that. This decrease in metabolism also leads to that decrease in respiratory rate, decreased heart rate, dry skin, and hair loss. The respiratory rate and respiratory and cardiac systems, they're slowed down. So the patient won't breathe as fast as normal. The heart won't pump as fast as usual. The hair loss and dry skin is a result of that lack of blood flow. Now, the key NCLEX point here is a decreased heart rate and a decreased respiratory rate. Edema and weight gain can also occur with this as well. As the heart slows down and it doesn't pump as hard or as fast, the blood can back up, the tissues can swell, causing edema. This can lead to weight gain along with the decreased metabolism. It's basically like the body isn't exercising it all on the inside. The metabolism is just super slowed down. It isn't burning enough energy and calories, so weight gain can result. Now, the GI tract will also be slowed down on top of the lack of blood flow because the heart isn't pumping as fast. So both of these factors can lead to constipation. And menstruation may also be affected. Those thyroid hormones can really mess with ovulation. So menstruation changes, menstrual changes can happen. And it could be heavier than usual, it could be irregular or maybe just skipped altogether, and the patient may or may not have a goiter. So because this is hypothyroid we're talking about here, there is less thyroid hormone. So how is it even possible that a goiter would be present if the thyroid gland isn't making enough thyroid hormone? Let's talk about it. So here's how this can happen, in particular during Hashimoto's thyroiditis and iodine deficiency, which are the top causes of hypothyroidism. So during Hashimoto's thyroiditis, the body's immune system, it's inappropriately attacking the thyroid gland, and it can cause the thyroid tissue to die. This can cause the thyroid gland to swell up, causing a goiter. And then during iodine deficiency hypothyroidism, the thyroid gland enlarges to try to keep up with producing enough thyroid hormone. Iodine is necessary to make thyroid hormones. So without iodine, the thyroid gland tries to compensate by enlarging, and this can form a possible goiter. So a goiter may occur in a patient with hypothyroidism, but it is more prevalent in patients with hyperthyroidism, but it still can occur with hypothyroidism. Now, if you want a deep dive into how to study pathophysiology easier in nursing school, definitely check out this video right here. And if this video helped you, write love in the comments below, because that is what we do here on my channel. And as always, my friend, go become the nurse that God created only you to be. And I will see you over there in that next video.