Hi class, we're going to be talking about metabolic and endocrine disorders today. We're going to start with thyroid. Just to review quickly, or let's talk about some thyroid tests just to kind of get your mind going in this way. You know, when you're talking about, for the most part, the TSH is going to really tell you what's going on. So for the most part, once you get your TSH and you start treating different things, that's your that's your main thing.
There often is not a need for further testing. However, a free T4 can be very useful. These are unbound. This is the active portion of the T4 that's left over, that's flowing in your system. It can be used as a follow-up test to confirm what's going on and support your diagnosis.
of hypo or hyperthyroidism in the face of an abnormal TSH. It's only a small percentage of all T4, but it has been found to be the most accurate. TSH is highly sensitive. And so it's often, you know, really your test of choice, but T4 can be used to confirm.
A total T4 is not as good as a free T4. It reflects the total amount of protein bound and free thyroxine together. And these are often altered. They're either increased or decreased in the absence of thyroid disease, but can be affected by certain medications such as estrogen, methadone, and others, and certain clinical conditions such as pregnancy and chronic hepatitis. So you can't completely trust that.
Free T3 is about 20% of your circulating T3. Again, it's that unbound portion of the T3. And then your total T3, of course, is all of it. It's rarely, these tests are rarely needed. You're really going to focus on your TSH and occasionally that free T4 to confirm.
The one other one you will use some is the thyroid paradoxase antibody or TPO. And this is when you're using, you're looking for autoimmune thyroid disease. And if it's autoimmune, it measures the antibody against peroxidase, which is an enzyme that's held within the thyroid.
So that can be your kind of test for autoimmune disease. So when you're getting that, when your thyroid status is stable and that HPA access is working well, then your TSH, again, that's your best bet when you're looking for any kind of thyroid disease. However, that serum free T4 can be more reliable, more reliable, more reliable indicator.
a thyroid status than the TSH when your thyroid is unstable, such as during when you begin treatment. There are some things that can vary TSH levels, time of day, some physiological conditions, illness, psychiatric disorders, starvation, but it still will almost always remain in normal range in the absence of thyroid disease. There's one other that's come around called the reverse T3. It's a biologically inactive form of T3.
It's producing the body during times of stress, and it's eliminated from the body really quickly. So it's often not very clinically useful for the evaluation of thyroid disease. It can have a help when...
you're looking at sick euthyroid syndrome. That's when the active T3 is normal and this reverse T3 is elevated. Sick euthyroid syndrome usually occurs when somebody is really sick, starving, critical illness, and they will present with a normal TSH and free T4, but they have a low free T3 and total T3.
So it's kind of a really different, we're not going to get deep into that, but that's the one instance when you might use this reverse T3. So let's talk about our different disorders of thyroid disease. We'll start with hyperthyroidism.
This is when you have an excessive secretion and synthesis of one or both of the thyroid hormones. And the signs and symptoms do result from the effects of these on the body. And we'll talk a little bit about those. There's several.
This usually is more common in women than men, peaks between ages 20 and 40. And there's several etiologies. The most common of these is it can just happen. But the most common is Graves'disease, which is an autoimmune disease.
Other things you'll see are subacute thyroiditis, which usually resolves. You can have a toxic multinodular border, which is producing excessive thyroid hormone. They can have an inappropriate use of their thyroid hormone because they're hypothyroid.
Also thyroid cancer and sometimes a tumor of the pituitary causing hypersecretion. That's a rare secondary cause of hyperthyroidism. Back when we're looking, I just want to go back a little bit to talking about the labs here. Just as a reminder, when you're looking at a TSH, because remember, your pituitary is what produces TSH.
TSH, thyroid stimulating hormone, is stimulating your thyroid gland to produce thyroid hormone. Well. If you have a lot of thyroid hormone being produced, then because of that negative feedback system, your TSH will be low in most hyperthyroidism. The TSH will be low and the free T4 is going to be elevated.
Because the thyroid is diseased, it's not responding to the low TSH and slowing down its production of thyroid hormone. It's diseased. There is a case in which somebody has hyperthyroidism and they would have an elevated TSH and an elevated T4, free T4. And that would be something going on in the pituitary gland. So if you have a tumor in the pituitary gland causing hypersecretion of TSH, the thyroid is not diseased, but it's responding to this constant secretion of TSH.
and releasing more thyroid hormone. And because of pituitary disease, it doesn't pay attention to this negative feedback system. And even though the thyroid hormone is very elevated, it continues to produce TSH. So that's the one instance when it would be the TSH and the thyroid hormone would be elevated. Here's some common symptoms of hyperthyroidism.
You might can remember them with sweating. We're going to go over some more symptoms as well, but, you know, it can be, they usually have weight loss and they lose muscle as well as fat. They have some emotional upsets. Their memory is not great. Their mind feels like it's racing.
They may have an increased appetite and actually continue to lose weight. They can have tremors, tachycardia. They're intolerant to...
peak, they have irregular menstruation, they can have irritability, very nervous, sometimes have a goiter, and sometimes have GI problems, which is some frequent low volume loose stools. The tachycardia is due to an increased stimulation of beta-1, causing that increased rate and increased force of contraction. This is just another list, same list, just put in a different format.
It depends on the duration and amount of excessive thyroid hormone as to how severe these symptoms will be. Some of them are rather subjective, so you need to take a really thorough history and review the systems. And don't forget those bowel symptoms, those are often overlooked and things like gynecomastia, we don't even think about that, but some of these can often be overlooked. They're going to have a decreased period of menses, irregular periods. As we move to hypothyroidism in a few minutes, you'll realize there's a few of these changes that are kind of across the board, like the fatigue, the insomnia, and that can go for both the depression, that can go for both hypo and hypothyroidism, decreased libido.
libido, but others of them are very much for hyper or hypo. So you think of hyper, you're going to think of speeded up. They can't tolerate heat.
They feel nervous. They can't concentrate. They can't sleep.
They're irritable. They have tremors, they have tachycardia, you know, they're losing weight because their metabolism is speeded up. So think about it that way. You're going to see some of the things you'll see on your physical exam.
These symptoms can range from overt manifestations in young adults. Remember, older adults might have a much more subtle presentation. They might come in with something like further to thrive.
But some of the things you're going to see from a physical exam, you're going to see, you know, cardiovascular, you're going to see tachycardia, increased pulse. You might hear murmurs, widening of the pulse pressure. You're going to see thinning hair, but the skin will be very velvety.
You might see increased pigmentation, increased spider angiomies, phylagio. There's several things you can see with the nails. So you're going to do a good skin assessment.
From a neurological standpoint, you'll probably see things such as spine tremors, the deep timber reflexes, Achilles specifically will be hyperreflexive. But they will have, they still will be weak. They're going to be kind of weak. Other findings are things, oops. Some of the eye findings when you do your eye exam might be the protrusion of the eyes or exophthalmos where you see the bulging eyes.
Eyes will often be red and you might see a lid lag in addition to that. So we kind of just have this really prominent fixed gaze. You may see excessive tearing as well and it can lead to some visual changes such as diplopia, photophobia, or just some eye irritation. Other findings you may note are things like nodules or a brewery heard over the thyroid gland.
The thyroid gland may become firm and painful with enlargement, and you'll see this in subacute thyroiditis. Usually, if it's cancer, it might be firm, but it usually won't be painful. In subacute thyroiditis, you'll also see elevated CRP and SED rates as well. Just to go back and think about, so what if you don't, what happens if it's not treated for a long time? So let's think about this.
It can have long-term effects. In the children, you can have alterations in growth. It can change metabolism and development.
So it's really not a good thing for a child to go undiagnosed. Long-term effects include... osteoporosis, heart disease, mental illness, and infertility.
So there's some long-term effects if it is not treated appropriately. So your initial testing, we talked about this, you're going to do that TSH level will be less than usually 4.35. You often, I've got a 3 T3 there, but really a free T4 is really what you need. So you're going to have an elevated free T4. I do remember there are some medications that can alter your free T4.
And these are things such as steroids, androgens, estrogens, heparin, iodine-containing compounds, bilantin, rifampin, and solicitates. So you're going to get that T3 only if you have something, your free T4 doesn't. You get the free T4.
3T4 and it is normal. That's when you're going to look at a T3. Other testing that might need to be done are things like a nuclear scan.
Then they do this with radio labeled iodine. This helps in assessing the function of the thyroid gland. They look at a 24-hour radio absorbed iodine uptake, identifies areas of increased and decreased thyroid function. This is often termed hot and cold spots. You can also use an ultrasound of the thyroid or cyst if you're looking to differentiate a cyst or a nodule.
Fine needle biopsy is the preferred initial diagnostic technique for evaluation of a thyroid mass. So, it's a mass, you know, you got something you need to see what it is, the needle biopsy is your way to go. Differential diagnosis.
Graves disease is one that's the most common. Thorough, uh, thyrotoxicosis where you have high levels of TSH, uh, can be seen, um, in a rare pituitary tumor. Um, we talked about excessive exogenous thyroid administration, uh, will produce the same symptoms seen, seen when it's actually something wrong with the thyroid, the irritability, the heart rate, all those things.
Thyroid cancer, cancer, you're going to see that. Um, um, if you see the hardened nodules, usually not painful. T4 levels can be elevated in some other instances as well. If you have an elevated estrogen level, acute psychiatric symptoms, if a patient is experiencing hyperemesis, there can be some familial thyroid hormone binding abnormalities that may cause this, and some medications can lead to elevated thyroid hormones such as amiodarone. amphetamines, glucocorticoids in high doses, heparin, heroin, of course, levothyroxine, methadone, and there's a host of others.
But these medications can lead you to have that elevated level. So let's talk about Graves'disease. It's the most common cause of spontaneous hyperthyroidism.
It is an autoimmune disorder. It's strongly correlated with other autoimmune conditions such as vitiligo, diabetes type 1, pernicious anemia, myasthenia gravis, adrenal insufficiency. These are some of the ones that can be correlated with. Some of the manifestations, you know, they're basically going to be hypermetabolic. and they'll have some sympathetic overactivity.
They often have diffusely enlarged quarters involving both thyroid lobes. It's somewhat firm. They may present with the hyperthyroid disease of the eyes where you'll get the paraordinal edema, conjunctival edema, injections, pitosis, lid lag, diplopia, and those other findings we discussed. When you're talking about the pathophysiology, that's when we're going to find the presence of antibodies to the thyroid stimulating hormone receptor. The antibody reacts with the TSHR on the thyroid follicular cells and allows release of high thyroid hormones independent of the effects of the pituitary TSH.
So remember, this problem is coming from the thyroid. It is not coming from the pituitary gland. That is why you'll have low TSH levels because the pituitary gland is saying, hey, hold on, too much thyroid hormone.
Try to slow it down. But because it is disease, it does not respond. Your management of hyperthyroidism really differs depending on the cause and patient characteristics.
This should be managed by endocrinology. Depending on what they find, you know, if this is some subacute issue, all of that depends on how they're going to go with the treatment. But treatment basically consists of sometimes they give radioactive iodine, which causes basically inflammation and destruction of the cells. And basically over time kills the thyroid gland. Other things they can do is they can do antithyroid medications such as PTU and MMI.
It takes two to eight weeks to see a therapeutic response. And there are some serious reactions related to this. They're rare, but things like agranulocytosis, plastic anemia, hepatitis, they are rare, however. Or a subtotal or total thyroidectomy.
These are just some of your possibilities. The beta blockers are given for faster symptom relief. They're given for symptom relief.
They don't really change how much thyroid hormone is being. put out there, but they do allow for some symptom relief while the patient is getting treated. Some things to teach your patient, you want to teach them about that disease process, the treatment options. You know, again, hyperthyroidism is going to usually be sent to endocrinology. However, they're going to be still coming back to you and you're going to need to explain this thing.
You want to make sure they report any signs of infection if they are taking the antithyroid medications, explaining how important it is to adhere strictly. Just some good lifestyle. is helpful and they need to be taught relaxation because they're very anxious.
Once in collaboration with your endocrinologist, once they're stable, they'll get thyroid function tests at least twice a year. Initially, they're going to be evaluated at one month and three months with the medication. The therapy with the antithyroid medications should continue for three to 12 months. If you see any signs of eye changes, you should send them to ophthalmology.
If they've had this condition for a while, they'll need a DEXA scan to see if they have developed osteoporosis secondary to it. Once they've had, if they choose the radial iodine therapy, you want to continue to do thyroid function tests for a while. Again, eventually what will happen with radial iodine therapy typically is that they will then the... Thyroid will be ablated, and then they will have to be treated for, they'll have to have thyroid replacement medication, levothyroxine.
And if they choose surgery to remove the entire gland, same thing. Another one to watch for, however, is subacute thyroiditis. It's another common cause of issues, and it's really a glandular inflammation and a destruction of the follicular cells. They think it's a viral etiology, but we're not. quite sure.
This is more common in middle-aged adults and still a greater incidence in women. This can be more silent in the form of subacute thyroiditis, in which the thyroid gland is just moderately enlarged and painful. Sometimes they run a low-grade fever, and you're going to want to kind of...
keep an eye on them, follow the thyroiditis. Some of them, this is only transient. They still are going to need the 24-hour radioactive iodine uptake test to rule out Graves'disease. And your treatment of subacute thyroiditis or subclinical thyroiditis is going to be very, very difficult. oops, is going to be a symptomatic treatment and often hydrocortisone.
One last thing to watch for when talking about hyperthyroidism is thyroid storm. Thyroid storm can occur. Some of the triggers you might want to know is Things such as acute infection, withdrawal if they quit taking their antithyroid medications, of course, trauma, stress, drug reactions, and uncontrolled diabetes.
This is emergent treatment is usually necessary. It is always necessary if they present a thyroid storm. They should be hospitalized for oral and intravenous hydration, for thyroid blocking medications.
beta blockers, IV beta blockers, and corticosteroids, especially if they have signs of changes in their eyes. There's symptoms that can come in with fever, nausea, vomiting, abdominal pain, confusion, some other agitation, diaphoresis, tachycardia, and all these symptoms they can come in with. So this is something to watch for.
One last thing is subclinical oh, here's, I'm sorry, here is your management of thyroid storm, which I just discussed. Lastly, there is subclinical hyperthyroidism, and this is characterized by undetectable TSH levels, so your TSH, your pituitary is not the problem, but you have, you can't, you don't see any, the TSH is not hardly there. However, they still have normal T4 and T3. So the treatment of this subclinical hyperthyroidism remains a little controversial, and these would always be referred to endocrinology. All right, and that is all for hyperthyroidism.
Thank you.