Med-Surg Endocrine System, part 15: Hyperthyroidism & Thyroid Storm (Thyrotoxicosis)
by Cathy Parkes August 19, 2020 Updated: December 29, 2021 9 min read
In this article, we cover primary, secondary & tertiary hyperthyroidism, and its related critical care topic: a thyroid storm. Knowing the pathophysiology, symptoms, diagnosis and treatment for these will be key in your Med-Surg exams as well as your nursing career.
These disorders are covered in our Medical-Surgical Flashcards (Endocrine system).
Hyperthyroidism is a disorder of the thyroid causing excess secretion of thyroid hormones T3 and T4 that causes the body to go into a hypermetabolic state. Similar to hypothyroidism, there are primary, secondary and tertiary causes of hyperthyroidism.
TRH, TSH, T3/T4 hormone review
If you remember from our overview on thyroid hormones, the hypothalamus produces thyroid-releasing hormone (TRH), which causes the pituitary gland to produce thyroid-stimulating hormone, which prompts the thyroid gland to produce the thyroid hormones T3 and T4. You can think of the chain like this
- Hypothalamus produces TRH
- Pituitary gland produces TSH
- Thyroid produces T3/T4
Pathophysiology of hyperthyroidism
To understand the differences between primary, secondary and tertiary hyperthyroidism, you can flip the chain backwards (so that you are starting from the thyroid).
- Thyroid produces T3/T4
- Pituitary gland produces TSH
- Hypothalamus produces TRH
In primary hyperthyroidism, there is a problem with the thyroid gland itself that’s causing it to secrete too much T3 and T4. The most common cause is Grave’s disease, an autoimmune disorder. In Grave’s disease, your body creates antibodies that basically trick your thyroid into growing and producing too much T3 and T4.
A thyroid nodule (small tumor) can also be an issue that causes excess secretion of T3 and T4 and thus, primary hyperthyroidism.
Secondary causes of hyperthyroidism occur when there is an issue with the pituitary gland, like a tumor. This causes excess secretion of TSH. With excess TSH, the thyroid gland thinks it needs to make lots of T3 and T4, even though it doesn’t need to. But the thyroid gland is just taking orders.
Throughout the Endocrine system section of this Med-Surg playlist, you’ve learned about multiple diseases where glandular tumors result in excess hormone secretion. Tumors that do this are known as “functioning” tumors, because they are actually taking on a job: making hormones. Sometimes the tumor actually harms the gland in a way where it can’t make enough hormone (e.g., secondary HYPOthyroidism), in that case, it is not a functioning tumor.
Tertiary causes of hyperthyroidism happen when there is a problem in the hypothalamus. Due to some dysfunction, the hypothalamus is producing too much TRH, which is causing the production of too much TSH, which causes the thyroid gland to go into overdrive and produce too much T3 and T4. Again, the thyroid gland is just taking orders!
Signs and symptoms
The thyroid is responsible for the body’s metabolism, so hyperthyroidism leads to a hypermetabolic state. Signs and symptoms of hyperthyroidism include tachycardia, hypertension, heat intolerance, exophthalmos (bulging eyeballs), weight loss, insomnia, diarrhea, and warm, sweaty skin.
If you want to think critically to deduce the signs and symptoms of hyperthyroidism, remember from our hormone overview what T3/T4 controls:
- T3/T4 controls metabolism. So when those hormones are high, the metabolism goes into overdrive and you see weight loss, warm skin, heat intolerance (feeling too hot) and insomnia (if you are hyper you can’t get to sleep).
- T3/T4 controls heart function. So when those hormones are high, you see that faster heart function with tachycardia and hypertension.
- T3/T4 controls digestion. So when those hormones are high, your digestion system is in overdrive too which results in diarrhea.
When it comes to the lab values you might see with hyperthyroidism, you will be looking at T3/T4 and TSH. The measurement of these hormones is known as a thyroid panel, which we explained in video 7 of this series.
The thyroid panel and blood glucose labs are the most important endocrine lab values to know for your Med-Surg exams, whether a course final, your ATI or NCLEX. Lab values can be dispersed throughout your textbooks, which is why we created our Lab Values flashcards, to keep the most important lab values you need to know for your exams all in one place that’s easy to study!
- Primary hyperthyroidism: High T3/T4, low TSH
- Secondary hyperthyroidism: High T3/T4, high TSH
- Tertiary hyperthyroidism: High T3/T4, high TSH
T3/T4 values with hyperthyroidism
In all types of hyperthyroidism, you will see increased T3/T4. That’s an easy one, because that’s what this disease is marked by!
The expected range for T3 in a thyroid panel is 70 - 204 ng/dL. T3 levels over 204 ng/dL can indicate hyperthyroidism.
The expected range for T4 in a thyroid panel is 4 - 12 mcg/dL. T4 levels over 12 mcg/dL can indicate hyperthyroidism.
TSH values with hyperthyroidism
The TSH value you will get back in a thyroid panel for hyperthyroidism really depends on if you are looking at primary, secondary, or tertiary hyperthyroidism
With primary hyperthyroidism, remember there is an issue in the thyroid gland itself causing excess production of T3/T4. However, the pituitary gland is functioning fine in this scenario, and its job is to scale back TSH production to prompt the thyroid to scale back T3/T4. The pituitary gland is scaling back, but the thyroid is not responding. So with primary hyperthyroidism, you will see decreased levels of TSH.
The expected range for TSH in a thyroid panel is 0.5 - 5.0 mU/L. TSH levels less than 0.5 mU/L can indicate primary hyperthyroidism.
With secondary or tertiary hyperthyroidism, the pituitary gland is in overdrive (by itself, or because of a dysfunctional hypothalamus) and therefore producing too much TSH — and that's what's prompting the thyroid to make too much T3/T4. So with secondary or tertiary hyperthyroidism, you will see increased levels of TSH.
TSH levels over 5 mU/L can indicate secondary or tertiary hyperthyroidism.
Treatment of hyperthyroidism
If a patient has primary hyperthyroidism, they may need a thyroidectomy, which is a removal of the thyroid gland. We go into more detail about a thyroidectomy in Video 16 of this series. After the thyroid is removed, the patient will be sent into HYPOthyroidism, and will require lifelong hormone replacement therapy with levothyroxine.
Some medication options for hyperthyroidism are propylthiouracil (PTU), a strong iodine solution, and beta blockers. PTU blocks synthesis of thyroid hormones, and an iodine solution is absorbed by the thyroid gland to inhibit thyroid hormone production and release. Beta blockers like metoprolol and propranolol can be used to bring down the high blood pressure and heart rate side effects that are seen with this disease.
If you need help remembering these medications for Med-Surg or Pharmacology, they are covered in our Pharmacology Flashcards!
If you have a patient with hyperthyroidism, you will want to increase their calorie and protein intake to offset the weight loss they are experiencing. The protein is important since that hypermetabolic state can reduce muscle mass.
Make sure to monitor this patient’s input and output, their weight, and their vital signs.
For a hyperthyroidism patient with exophthalmos, you will tape their eyelids closed for sleep so their eyes don’t dry out. You definitely want to explain this to the patient carefully because it can be scary when you wake up and your eyes don’t open! You will also provide eye lubricant to help protect the eyes.
Thyrotoxicosis (thyroid storm)
Hyperthyroidism is a disorder you need to know for your Med-Surg classes and exams, and a thyroid storm is a critical care topic that builds on your knowledge of this disorder.
Thyrotoxicosis is an acute, life-threatening complication of hyperthyroidism known as a thyroid storm, with extremely high levels of thyroid hormones. This is usually brought on by infection, stress, diabetic ketoacidosis (DKA), or even after a thyroidectomy.
Signs and symptoms
Signs and symptoms of thyrotoxicosis include severe hypertension, chest pain, dysrhythmias, and dyspnea (difficulty breathing) due to respiratory exhaustion.
A patient undergoing thyroid storm can be given beta blockers to get the vital signs under control, antithyroid medications to stop the problem at the source, and antipyretics (anti-fever medication) like acetaminophen to bring the fever down.
Because a patient in thyrotoxicosis is having trouble breathing, your most important nursing priority becomes maintaining a patent airway. Then, monitor this patient for dysrhythmias.
Cathy’s teaching on hyperthyroidism disorder and its complication thyrotoxicosis is intended to help prepare you for Medical-Surgical nursing exams and critical care. The Medical-Surgical Nursing video series is intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI and NCLEX.
In this video, we are going to talk about hyperthyroidism as well as thyrotoxicosis. If you are following along with cards, I'm on card 37 [of the Endocrine system section in the Medical-Surgical Flashcard deck].
With hyperthyroidism, we have excess secretion of T3 and T4 from the thyroid gland, and just like we saw with hypothyroidism, we have primary, secondary, and tertiary causes of this disorder.
And if you recall, the hypothalamus produces TRH, thyroid-releasing hormone which causes the pituitary gland to produce TSH, thyroid-stimulating hormone and that allows for secretion of T3 and T4 from the thyroid gland.
If we have an issue with the thyroid gland itself - so that would be primary hyperthyroidism - the most common cause is Grave's Disease which is an autoimmune issue, but we can also have some kind of thyroid nodule. Due to one of these causes, we have hypersecretion of T3 and T4. So that's primary hyperthyroidism.
With secondary hyperthyroidism, this is where we have some kind of pituitary disorder such as a tumor, which is causing excess secretion of TSH. So with all this extra TSH, the thyroid gland is getting the message to produce more and more thyroid gland hormones even though it doesn't really need to, but that's the order it's getting from the pituitary gland.
And then with tertiary hyperthyroidism, that means we have an issue in the hypothalamus. So due to some kind of hypothalamus dysfunction, the hypothalamus is producing too much TRH, which is causing the production of too much TSH, which is causing the thyroid gland to go into overdrive, producing all that T3 and T4 even though it really isn't supposed to just because it's getting that order from above.
So those are the three causes of hyperthyroidism. So with all that T3 and T4 being produced by the thyroid gland, it really puts the body into a hypermetabolic state.
So signs and symptoms of hyperthyroidism include tachycardia, hypertension, heat intolerance, bulging eyeballs, which is something called exophthalmos, weight loss without trying, insomnia, diarrhea, and warm, sweaty skin.
In terms of the labs we'll see with hyperthyroidism, T3 and T4 levels will be elevated. TSH levels will depend on whether we're talking about primary or secondary hyperthyroidism.
So with primary hyperthyroidism, that's where we have Graves' disease or a thyroid nodule, that thyroid gland is just cranking out the T3 and T4 regardless of how much TSH it's getting. The pituitary gland's over here really concerned, like, "Wow, you're putting out a lot of T3 and T4. Can you please chill out?" And the thyroid gland's like, "I can't chill out. I got to keep making my T3 and T4." So the pituitary gland is scaling back how much TSH it gives the thyroid gland, but the thyroid gland doesn't care. Doesn't care and is going to keep cranking that stuff out as fast as it can. So with primary hyperthyroidism, elevated T3 and T4 but decreased TSH because that pituitary gland is trying to rein that thyroid gland in.
When we have secondary or tertiary hyperthyroidism, then our levels of TSH will be increased, right, because there's some kind of tumor or malfunction which is causing increased TSH, which is causing the thyroid gland to produce more T3 and T4. So the thyroid gland is functioning fine. He's like, "I think I'm making enough T3, T4 here." But the pituitary gland's going crazy and is like, "No. Here's some more TSH. Make more. Make more." And the thyroid gland's like, "Okay, I'll do that." And that's secondary hyperthyroidism. So with that, we'll have elevated TSH and elevated T3 and T4.
Let's move to treatment.
If a patient has primary hyperthyroidism, they may need a thyroidectomy, which is removal of the thyroid gland. And in my next video, we will talk about nursing care of patients who have to undergo a thyroidectomy.
Medications that could be used include PTU, iodine solutions, as well as beta-blockers to help bring those vital signs down.
In terms of nursing care, we're going to want to increase our patient's calorie and protein intake because of that weight loss and the fact that they're in this hypermetabolic state.
We're going to want to monitor their I's and O's as well as their weight and their vital signs.
And then for exophthalmos, which is the bulging eyes, we're going to want to tape their eyelids closed for sleep and provide eye lubricant to really protect those eyes.
Let's briefly talk about a life-threatening complication of hyperthyroidism which is thyrotoxicosis, or a thyroid storm. This is where we have excessively high levels of thyroid hormones. And this could be brought on due to infection, stress, diabetic ketoacidosis, which is DKA, or possibly due to a thyroidectomy.
In terms of signs and symptoms of this disorder, we're going to have severe hypertension as well as chest pain, dysrhythmias, dyspnea, which is difficulty breathing, delirium, fever, and nausea and vomiting.
In terms of treatment, we can give this patient beta-blockers to try to get those vital signs in control, antithyroid medications, as well as antipyretics for treating the fever.
And in terms of nursing care, we're definitely going to want to maintain a patent airway, which is always your number-one priority, and then also monitor the patient for dysrhythmias.
That is it for hyperthyroidism. In my next video, we will talk about care of a patient who requires a thyroidectomy. Thanks so much for watching!
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