High TSH Levels: Lab Interpretation for New Grad NPs
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Show notes:
Finding a high TSH on a screening test or when you've ordered it for a fatigue workup is SO common in primary care.
But when do you actually need to treat it? And how?
Diagnosis and Management of High TSH
Using a case study, you'll learn:
When to worry about a high TSH
The first steps you need to take first to manage it
How to follow up and assess your treatment
And other pearls of practice when it comes to a TSH
Continue Learning: Lab Interpretation Series Bundle
If you liked this episode, it's a sneak preview of how we cover labs inside our comprehensive Lab Interpretation Series Bundle. It’s an ANCC-accredited CE bundle of courses that covers CBC, BMP, Renal Labs including Urinalysis, Dipstick & Microscopy, Microalbumin, TSH, and Hyperlipidemia in primary care! Check it out here.
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Hey there, it's Liz Rohr from Real World NP and you're watching NP practice made simple. The weekly videos to help save you time, frustration and help you learn faster, so you can take the best care of your patients. So if you find yourself a little bit mystified by TSH wondering what is the range to worry about? Who should be treated? How you treat them? How you monitor them? Like any of that stuff, I got you. This is what this video is all about is managing high TSHs. So before we dive into this case study, quick note is that I'm working on the lab interpretation crash course for new nurse practitioners. So it's kind of similar to the way that I'm talking about labs in these videos, much more nuts and bolts, very concise, very practical, all of the labs that you see in primary care.
So kind of touching on the way I've touched on them so far in the videos that I've made so far only in a very compact, very straight to the point, let's do this kind of way. It's actually turning out way better than I had hoped. And I'm actually doing it in collaboration with a couple of specialists, just to kind of give that extra level of added touch on in terms of like maximizing the most you can do in primary care while at the same time, just being really thorough. And it's going to have some extra stuff thrown in there. I don't want to unveil too much right now, but if you're interested in that I'm super, super psyched about it. Head over to realworldnp.com/labs and I'll send you an email when I have more details of when it's going to be rolled out and it's going to be in the next couple of weeks. I'm really, really psyched about it. But anyway, without further ado, I'm going to share my screen with you.
So this is the Hypothyroid Case Study. So this is Janelle, she's 56, she's a new patient establishing care and she complains of fatigue. And if you've seen these before, this is not her real photo or her name. So she's complaining of fatigue with heavier periods for the last two months. And they've been more irregular recently, she's complaining of some weight gain, but unable to quantify it in terms of specific pounds, she used to take levothyroxine in the past. She doesn't like taking pills, I'm not sure if she needed them. Her past medical history, past surgical history include hypothyroidism, anemia, cholecystectomy, obesity. No family history, a non-smoker, no alcohol or drug use. And at this visit her blood pressure is 169 over 79 heart rate of 77. Oxygen is 98 and BMI is 37. Her physical exam is normal. So I did like a general cardiovascular respiratory HEENT, including thyroid and extremity exam.
I didn't mention the full ROS here because I'm not really getting into like fatigue as a complaint today, but just kind of in general, those are the main positive ROS is in the history that I said so far, and then her physical exam was normal. So the plan, so today I'm going to focus on hypothyroid, but I'm going to touch on the other components of holistic care at the end. So I'm going to check her labs. CBC because she had a history of anemia and she's feeling fatigued, a CMP, a hemoglobin A1C, a TSH and so I have a note here of reflexes because some labs you can order a TSH and reflexively they will automatically order a Free T4 and a T3 if it comes back abnormal, I did not have that option, but just if you do, you can order that. And lipids, cholesterol according to USPSTF's screening guidelines.
So here are her lab results TSH is 5.520, a Free T4 of 0.69, which is normal, hemoglobin A1C of 5.7%, which puts her into the prediabetes range. Her cholesterol is high, her CBC and CMP are both normal, luckily. So yeah, hypothyroid it means that a high TSH signifies that there is a low functioning thyroid, typically speaking in this case of what we're talking about. So it's kind of opposite to what you think. And it's diagnosed by labs also based on their symptoms. So I'm going to give a disclaimer here that this is for non-pregnant adults. If you're going into pregnancy, pregnant women, this is outside of the scope of this presentation and that those patients need to go to endocrine or you need to consult with endocrine when you see them. So what are the steps of hypothyroid management?
I'm really looking at the workup according to the labs and management. I'm not going as in-depth with the workup and more specifically talking about the management. So first step is how high is the TSH and what is the total of free T4? So you really need to look at both. So normal range, according to your lab, depending on your lab rather is 0.4 to 4.5 and free T4 normal range is 0.6 to 1.8. And the note here I want to make is that it's free T4, not total T4. So total T4 is bound to protein. It's not clinically relevant for this situation. Only the active kind of free form is T4 or unbound rather, not the active. Repeat TSH with free T4 to help confirm the diagnosis is really the consensus first step, you can either add on the free T4, if you have an abnormal TSH, if you call your lab or you can have them come back to repeat it to make sure that it's not like a transient or abnormality.
There's no real like problem with this lab in the case that there is for like high potassium or low platelets in terms of like high risk of artifact. But that's kind of just like a consensus model and there's no absolute danger numbers similar to my other presentations I kind of gave those danger ranges. And it's really not. It's based on symptoms. The extreme case of hypothyroid is myxedema coma, which you probably learned about in school, is very uncommon. Mental status changes, extreme lethargy, hypothermia, things like that. So they would kind of present to you, and you'd kind notice send them to not your clinic, if you're working in primary care, probably the ER.
So really, there's no highest number of TSH. The highest I think I've seen is like 30, maybe 50, maybe 80. I actually can't remember, but they were fine. So there's two scenarios, main scenarios. One is a high TSH with a low T4 and that's considered overt hypothyroidism. Whereas a high TSH, for example, 12 and a normal T4, for example, one, is considered subclinical, but it depends on their symptoms. So if they have no symptoms, they have a high TSH and a normal T4 that's considered subclinical hypothyroidism. So I'm going to take a note about subclinical. So there isn't really a set like you have to do this, but typically for patients who have a persistent TSH of greater than 10 with a normal T4 and they're asymptomatic, you could consider treatment for those patients because it's most likely that they're going to follow the natural history of the most common type of hypothyroidism, which is that autoimmune Hashimoto's. If ages 65 and up, especially with cardiac disease, the TSH norm is actually considered to be higher.
Actually, you can treat them within the normal ranges and I'll get to management in a second, but you could actually let their TSH be as high as up to 10, even under management because of the risk of adverse effects in terms of metabolism and cardiac effects and all that. So if a TSH is less than 10, there's no symptoms, you can kind of recheck those people in three to six months, depending on the clinical scenario. And this is kind of a side note, I'm jumping a little bit ahead in this by saying this, but considering checking a TPO antibody to see if this is Hashimoto's versus transient, there's different types of hypothyroid and the Hashimoto's is going to be kind of correlated with that TPO antibody, but you do not have to automatically order that TPO antibody. That's really just in case of like, you're not sure what type of hypothyroid this is.
So in terms of the management, how high is the TSH? What is the free T4? Next step, is this a new or established diagnosis or lab value? So like I alluded to there's several types of hypothyroidism. Number one is Hashimoto's and autoimmune, vast majority, absolutely what you're going to see vast majority in primary care as well. I'm not really going to get into workup again because it's kind of outside the scope and I'm trying to keep this short and sweet, but also central hypothyroidism, transient hypothyroidism. Have you had a radiation to your neck or surgery to your neck like a hypo parathyroid recent surgery? Any drugs? There are two drugs in particular I'll touch on in a second. You want to look at the previous labs and then the clinical scenario. So has this been persistently elevated? Is it still... Is it the first time you've seen it?
Do they have other symptoms going on? Are they postpartum that can happen with a transient thyroiditis? Any recent illnesses? Other lab abnormalities or symptoms that just don't really match up and you're like, you know. What I'm kind of referring to here is with the majority of what I've seen in primary care is like someone will be fatigued or they'll have some symptoms of hypothyroid. You do a screening lab, or you're just doing a screening lab and you come back with a TSH that's abnormal and their T4 is also is... The TSH is high and the T4 is normal what are you kind of doing for those people? That's the vast majority of people. And then if you find it as a high TSH with a low T4 vast majority, again are going to be that Hashimoto's thyroiditis, that kind of autoimmune destruction of the thyroid.
So you kind of just want to look at the whole picture and see, and then if it doesn't seem like that really matches up, they've got other symptoms going on. Their labs are kind of just not really matching, like looking at those other kinds of differential diagnoses there, but vast majority of people have Hashimoto's. So drugs, lithium, good medication but a lot of side effects. Amiodarone not as common, but common enough to mention, the rest of them are not really common at all. Interferon alpha and interleukin-2, tyrosine, kinase inhibitors, certain immunotherapies like I think there were some other chemotherapeutic type of medications. And so if you have any kind of unusual medications that are outside the scope of typical primary care medications, I would definitely check and see if there's any side effects for those. But those were the kind of main ones that I saw that I'm aware of rather.
So number one, how high is the TSH and what is the free T4? Is it a newer established and are they symptomatic? So symptoms just to recap. So cold intolerance, fatigue, constipation, dry skin, hair loss, weight, gain, menstrual irregularities. They can also have bradycardia, diastolic, hypertension and delayed DTRS, deep tendon reflexes. They may have goiter because Graves' disease has an enlarged thyroid, but when you're overstimulating your thyroid all the time to try and make it work more, it can become enlarged. There are some cases of that. I usually also ask about any dysphagia or compressive symptoms, like is there some enlargement that on my thyroid exam it doesn't feel enlarged or there's some nodules that I'm not feeling things like that.
So the four steps to hypothyroid management. So number one is overt versus subclinical. So I kind of mentioned this already, are we talking about a high TSH with a low T4 or high TSH with a normal T4 and they have no symptoms. And number two is just ruling out those alternatives like does the clinical picture make sense or does it not? Do you have to kind of look into those other ones? Number three is to start with levothyroxine that's the main treatment for hypothyroid. And number four is monitoring the labs and the symptoms. That's really the main treatment.
So what's next? So let's go back to Janelle for her we can proceed with management her TSH is less than 10, but she is symptomatic. She's got weight gain, she's got irregular menses, she's got fatigue. She has had treatment in the past as well. And so we know that this is not a new hypothyroid for her, even though she's a new patient, we don't have our previous records. So for her, and I'm going to jump into management in the next slide, but we're going to start with 50 micrograms and recheck her labs in six weeks. So let's look at management.
So this is the general management for anybody with a low persistently high TSH, low functioning thyroid with a low free T4. So start levothyroxine and you can either do weight-based or standard dosing. I honestly go for standard dosing all the time, either 25 or 50 micrograms to start. This is the calculation if you're interested in weight based, it's 1.6 mics per kilogram, per day of lean body weight. This patient's BMI was 37, so you'd want to calculate the lean body weight and then calculate it based on there. But if you're talking about a 70 kilogram person, that's a pretty high dose, that's about 112 micrograms. And so I don't think I go right out of the gate, giving somebody that because I've seen people all over the place, respond to 25 and then respond to 200.
It's very hard to know. So after you pick your starting dose, I actually a note about the 25 to 50, if I have anybody 65 and up or cardiac issues then I'll start at 25, depending on how high their TSH is, if it's super high and they're younger than 65 and they have cardiac issues, I might still go for 50, but that's usually when I reserve the 25. So you're going to recheck the TSH in six weeks and that's because of the half-life of the medication. And the goal for treatment is to get it back into the normal range of 0.5 to five, approximately do an inner lab again. And it's okay to be under 10 for age 65 and up is what I've read recently. And I typically would correct them to within that five range. But I read that recently that that is something that is more encouraged. And I don't know if that's official guideline or that's kind of expert opinion, but that's something to think about.
And so you could consider rechecking in three weeks if they're still highly symptomatic and just kind of see, are we making progress here or not? And again, adjusting by 12 to 25 mics each time and that's using your clinical judgment, whether it's up or down. And so if the TSH is still high and they're still symptomatic, keep going up and you can either do 12, if it's like slightly high or 25, if it's very high, like it's really just up to you. And what you're going to do is recheck the TSH again in another six weeks. And the 12 micrograms just comes down to the dosing, honestly.
So if you're not familiar with the dosing, it starts at 25. I don't think there's anything less than that. You have 25, 50, 75, 88, 101, 112, 125. I think it actually goes up to 150 or maybe there is 137. Yeah, it goes up by those 12 microgram intervals. And so that's really kind of excuse me up to you and your discretion and if they're older or if they have any cardiac issue, you want to go a little bit more slowly and maybe choose that 12, if they're getting close to their goal range of the TSH.
So a couple of rules of practice. Levothyroxine is a synthetic T4 hormone. Armour thyroid, I actually will not be able to pronounce the generic name for T3, but that is one of the brand names available for T3 and not an advertisement is a bovine source pig thyroid as far as I understand, it's "natural" you'll see that's how some people will refer to it and prefer it that way. I find that it's a really irregular dosing in a higher risk for adverse effects because it's not really as regulated because it's not like pharmaceutical. I mean, it is, but that's a whole discussion, but it's just not as reliable. So if somebody needs to be on T3, there are some instances where people will need both T3 and T4, but I'm going to let that go to the endocrinologist if somebody comes in with that, and if somebody kind of brings to your clinic like that question, you can definitely kind of give them that answer of why you don't really feel comfortable giving T3, unless you want to give T3 in which case that's absolutely totally fine.
And it doesn't actually matter if it's an empty stomach or not. The traditional advisement is that it's on an empty stomach two hours before anything else. But honestly, and this comes from pharmacists advice at a prescriber's letter is that as long as it's consistent, it's just more important that they're doing it the same way every time. So taking it with a full stomach or the same type of meals, and then there maybe, you may need to do a higher dosing in some settings, things like nephrotic syndrome, celiac disease, certain medications. Celiac disease, because of the malabsorption, certain medications like phenytoin and carbemazepine, phenobarbital and pregnancy. And I'm going to say that again, but I am not treating those patients in pregnancy because that is very important for fetal development and way outside the scope of primary care. So definitely get endocrine involved if you have a pregnant patient.
So let's go back to Janelle. So we did her thyroid management like I said, 50 micrograms recheck in the TSH in about six weeks and it started to go back to normal. So we're still in the 50 micrograms for her. So it's really important, I want to make a note here of having a healthy skepticism. So sometimes when you come in, we just have these everyone has a risk for cognitive bias, right? And so she has a history of hypothyroid. She has all the things that kind of match up with thyroid, but like the clinical picture, like honestly her TSH was not that high and her T4 was still normal. So we had a mutual discussion decision-making to restart it, but I'm considering a further fatigue workup for her pending on how she feels with a full six weeks until we recheck it.
And looking for things like sleep apnea, she has a BMI of 37. So something to think about there. I did an ultrasoud for perimenopausal menorrhagia. So another topic in and of itself, but with menorrhagia in the perimenopausal and definitely menopausal is really concerning. But the perimenopausal status, like over age 40 with the risk factors like obesity is one of the risk factors of endometrial hyperplasia. And so those patients may actually qualify directly for an endometrial biopsy, but endometrial ultrasound is a little bit more less invasive, less uncomfortable. So I did an ultrasound for her and based on the measurement of her endometrial lining, then we can consider monitoring or doing an endometrial biopsy. I actually do those in my clinic, but you can send them to GYN for that. It's actually not that invasive of... It's an invasive procedure, but it's not that complicated.
We had a discussion about hypertension. Remember her blood pressure is 169 systolic. She really didn't want to take any medications and she's been working on dietary changes and she feels like taking the medication for thyroid is really going to help her. We had a discussion about pre-diabetes and hyperlipidemia, same thing. She wants to work on diet and exercise. She actually is doing a lot of work on her own, but she's hoping that the thyroid supplementation will be really helpful. And then I just had her come back in a month because I really want to dig into more of the sleep apnea, fatigue workup. Like there's a whole workup that can go along with fatigue in terms of like the history questions you ask and the labs you could do, things like that.
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