Hyperthyroidism: Introduction (Nursing)

00:01 Hi, I'm Doctor Rhonda Lawes, and I want to welcome you to our series on thyroid dysfunction. Now let's start with hyperthyroidism.

00:09 Primary hyperthyroidism happens when the thyroid gland produces and releases excessive amounts of thyroid hormones, T3 and T4.

00:19 Now there's also another hormone involved TSH.

00:23 Thyroid stimulating hormone is produced by the pituitary gland, which acts as the master regulator of the thyroid system.

00:31 Now, when TSH is released, it stimulates the thyroid gland to produce the two main hormones T4 and T3.

00:39 T4 is the primary hormone produced by the thyroid gland in response to the TSH, the thyroid stimulating hormone that comes from the anterior pituitary gland.

00:49 Now, T4 is considered a prohormone because it has to be converted into T3 to be fully active.

00:56 Now, when we talk about T3, keep in mind some of the T3 is produced directly by the thyroid gland, but most of the T3 is created when T4 is converted in various tissues throughout the body.

01:09 T3 is the more active form and has a stronger effect on the metabolism.

01:14 Now these hormones also operate in a negative feedback loop, so when T3 and T4 levels are low, the hypothalamus is realized.

01:22 Wow, we don't have enough.

01:24 So it releases TRH . And this causes the pituitary to release more TSH. So when T3 and T4 levels are high, the hypothalamus will slow down the release of TRH and the pituitary will reduce the TSH stimulation. And there is the feedback loop when the hypothalamus picks up, hey, we don't have enough thyroid hormone in the body, it will send out the TRH, which targets the anterior pituitary, which releases more TSH, which targets the thyroid gland to put out T3 and T4. Now just the opposite works.

01:58 That's the negative part when T3 and four levels are high, the hypothalamus doesn't need to put out the TRH, and therefore there's not as much TSH to stimulate the thyroid gland.

02:09 That's the magic of the endocrine system.

02:12 So this is why TSH levels are often used as the first test for thyroid function.

02:16 So high TSH usually indicates an underactive thyroid or hypothyroidism. Now think that through.

02:24 You know what TSH does, right? We've got TRH from the hypothalamus.

02:28 Then the anterior pituitary puts out TSH.

02:31 And that's what should stimulate the thyroid gland to put out the T3 and T4.

02:36 But if you have high TSH that's telling you wow, the hypothalamus is seeing there's a problem.

02:41 It's sending TRH and then it's going to the anterior pituitary hitting the TSH.

02:45 But the thyroid gland can't respond.

02:48 That's why it's a signal that it's hypothyroidism.

02:51 Now what if the TSH is low.

02:54 Well, this usually indicates an overactive thyroid, and therefore you're not having TSH sent out by the anterior pituitary gland to stimulate the thyroid.

03:11 The relationship between these hormones demonstrates this really delicate balance in the body, because it is crucial for maintaining proper metabolism, growth, and development throughout the body.

03:23 Now, if you have excess thyroid hormones, this is going to increase the metabolic rate.

03:27 So you're going to notice things in your client like an increased heart rate and an increased cardiac output.

03:32 Their metabolism will be accelerated.

03:34 They are not going to be able to tolerate any heat.

03:37 They may lose weight despite them eating more than they used to.

03:41 They can also have anxiety and tremors.

03:43 Think of that as like this increased sympathetic response.

03:48 Now, the most common cause of excess thyroid hormone is Graves disease.

03:51 This is an autoimmune condition where antibodies stimulate the thyroid hormone production.

03:57 Let's take a look at the risk factors for Graves disease.

03:59 As you know, this is the most common cause of hyperthyroidism.

04:03 Now first I want to talk about those risk factors that have the strongest evidence that supports them as being risk factors.

04:09 First is sex. The female sex has a significantly higher risk for developing graves disease.

04:16 Now, other things you want to be aware of when you're doing a history and assessment of your client, ask them if they have any family history of thyroid or even autoimmune disorders. Now their age also comes into play.

04:28 This is most commonly diagnosed between age 30 and 50 years.

04:32 So I want to go back and reinforce.

04:34 Remember they might have a family history of thyroid or other autoimmune conditions. Now the last I want to talk about is smoking.

04:42 When we're talking about the strongest evidence base, smoking doesn't do anything good for us, but it both increases the risk and worsens the outcomes for a client with graves disease. Now, there's moderate evidence for these three factors pregnancy and postpartum period, significant stress, and even some genetic factors.

05:02 Now, there's a few other things I want to talk about, and the evidence for these as direct risk factors is less definitive for things like radiation exposure, iodine excess, and viral infections.

05:13 Now, these may be associated with thyroid disorders in general, but their specific role in triggering Graves' disease requires more research.

05:21 So that's a basic overview of the risk factors for developing Graves' disease.