Voiceover: Welcome to NP Certification Q&A presented by Fitzgerald Health Education Associates. This podcast is for NP students studying to pass their NP certification exam. Getting to the correct test answers means breaking down the exam questions themselves. Leading NP expert Dr. Margaret Fitzgerald shares her knowledge and experience to help you dissect the anatomy of a test question so you can better understand how to arrive at the correct test answer.
So, if you're ready, let's jump right in.
Margaret Fitzgerald: A 45-year-old woman with a 10-year history of hypothyroidism presents for follow-up care. She's been taking levothyroxine 100 micrograms per day with excellent adherence, stating, “I take the medicine every morning on an empty stomach with a big glass of water.” She states she's generally feeling well, but notices increased fatigue over the past 4 months, which she attributes to the stress of starting her graduate studies while working full-time.
The results of today's laboratory testing include the following:
TSH 2.3 (Normal 0.4 to 4)
Free T4 15 (Normal a 10 to 27)
The next step in her care is to:
A: Continue on the same levothyroxine dose and obtain a repeat TSH in 1 year.
B: Increase the levothyroxine dose by 25 micrograms per day and repeat TSH in 1 month.
C: Increase the levothyroxine dose by 25 micrograms per day and repeat TSH in 2 months.
D: Repeat the TSH and free T4 today and provide counseling about taking the medication with breakfast.
The correct answer is A: Continue the same levothyroxine dose and obtain a repeat TSH in 1 year.
Where should we start? First let's determine what kind of question this is. We are given the patient's diagnosis. She has been treated and now is here for follow-up. And this is an evaluation question. Focused on response to the treatment plan. As we do with all of these, let's take a look at a bit of background information. Hypothyroidism is a condition where the amount of thyroxine, a.k.a. T4, released by the thyroid is inadequate to meet the body's metabolic need.
In North America, hypothyroidism is usually the result of Hashimoto's thyroiditis, which is an autoimmune condition leading to thyroid failure. Hypothyroidism is far and away the most common thyroid disorder that is going to be encountered in primary care. The most common clinical presentation of hypothyroidism is noted in female patients between the ages of 30 to 50, and it tends to be really quite nonspecific, such as dry skin, unexplained fatigue, new-onset or worsening of constipation.
And when you think about it, and again, my comments are much colored by the fact that I live in the Northeast where it's cold in the winter time. You know, dry skin is still nonspecific and can be weather-induced, unexplained fatigue. Now, winter in New England, sometimes people feel really tired. And part of it is because they're worn out from the weather.
And constipation common complaint, not specific to hypothyroidism at all. So, in other words, a number of signs and symptoms that can be attributed to a variety of other diseases. Of course, we're being told here this woman has already been diagnosed with hypothyroidism, and issues pertaining to diagnosing and hypothyroidism are actually covered in another one of the Q&A podcasts. How about then focusing in on the treatment of hypothyroidism. If more replacement is needed in the form of levothyroxine brand name, Levothroid, Lovoxyl, Synthroid. There's also generic. The dose of levothyroxine is based on ideal body weight.
In other words, in the person who's overweight or with obesity believe our thyroxine dose would be calculated on what would be their ideal body weight. In a person who is at a healthy weight or underweight, it's calculated on what their actual body weight is. Levothyroxine at 100 micrograms is a fairly standard dose. Remember, you don't need to memorize drug doses for the board because that would be considered your ‘look-up’ information, not your ‘walking around’ information.
And levothyroxine is one of those meds that I refer to as a fussy drug. And in other words, it likes to be in the stomach all by itself. If it's taken at the same time as other medications, including calcium, magnesium, or iron, with a myriad of other meds, the levothyroxine dose will simply be less available.
To give you an idea, 100 micrograms of levothyroxine taken with two Tums, and Tums contain calcium, will probably only give about 33 micrograms of levothyroxine, will actually be available to the patient. And that's one reason why the advice with levothyroxine is to take it on an empty stomach with nothing else around it, including food.
Levothyroxine doses should be titrated to the point where the TSH and the free T4 are within normal limits. So now let's take another look at her labs. What were her levels? Both TSH and free T4 were within normal limits, were they not? Yes, they were. So, in established hypothyroidism, thyroid hormone requirements can remain stable over time.
Once adequate replacement dose has been determined, periodic TSH measurements should be done. And when first getting somebody to goal, you oftentimes do need to repeat the TSH a number of times to titrate that person to goal. But once they have that TSH and free T4 goals, then repeat at 6 months and then at 12-month intervals, of course more frequently if the clinical situation dictates otherwise.
In this case, it's not mentioned, but she's in for follow-up and it says she's tired. And so, a TSH and free T4 was done. Perfectly appropriate, but both within normal limits. So, with that as background information, let's take a look at the question and the possible responses. A 45-year-old woman with a 10-year history of hypothyroidism presents for follow-up care.
She's been taking levothyroxine 100 micrograms per day with excellent adherence stating, “I take medicine every morning on an empty stomach with a big glass of water.” She states she generally feels well, but notices increased fatigue in the past 4 months, which she attributes to the stress of starting her graduate studies while working full-time. The results of today's laboratory testing include the following TSH at 2.3, with the norm being 0.4 to 4, and free T4 of 15 with norm being 10 to 27.
As an aside, before we go into this, remember you'll be provided with lab results on the boards. The lab norms or what would be described as, you might not get the numbers, but what you might be given is question like this. It says TSH and free T4 are both within normal limits. You know, you're going to get a verbal description of what the lab results are.
So, okay, now back to the question. The next step in her care is to A: Continue the same levothyroxine dose and obtain a repeat TSH in 1 month. This is, of course, the correct answer. Please note your TSH and free T4 are both fine and dandy. That is the goal of treating hypothyroidism. You might be tempted to put the ‘yeah, but’ into the question and other words, like the patient saying she's tired at the same time.
Remember, she's offering an incredibly valid reason for feeling tired. And I suspect that all of us can identify with this. She has decided to go to grad school, but was she going to cut down on part-time work? No, she's not. She's going to go to school full-time and now she's going to graduate school. Anyone else remember being this tired?
Some of you were this tired already. I'm not saying, 'Just brush off her complaint of fatigue.’ Certainly, it should be more deeply investigated. And what I would go into is sleep hygiene. You know, maybe she used to sleep 8 hours, 7 or 8 hours at night. And because of grad school, she's sleeping 4 or 5 hours a night.
What does she do for stress management? One more time not to hyper-identify with somebody in graduate school. But, you know, well, many of us had our stress management routine fly out window during graduate school, like, you know, not exercising as much, taking some time for yourself, that type of thing. I would even include menstrual history because she is a perimenopausal woman, perimenopause usually being between the ages of about 45 to 55 for women.
She could be developing an iron-deficiency anemia. At the same time, she appears to be biochemically euthyroid, within normal limits. She's tired, but we can't pin it on her thyroid. And I know that that can make people feel really uncomfortable when I say that. But this kind of question, that's exactly what it's trying to do, is have you come back and say, ‘Yeah, she's tired, but it's not her thyroid.’
Option B: Decrease levothyroxine dose by 25 micrograms and repeat TSH in 1 month. This is incorrect of course, since your thyroid labs are within normal limits on her given dose of medication. In addition to the long half-life, even if her levothyroxine dose needed to be adjusted, the time to wait on rechecking TSH should be about 6 to 8 weeks not 1 month.
You know what I do? I just always tell patients like change your thyroid medicine dose. We're going to repeat it 2 months. Just keep it simple, and not the 6 to 8 weeks. Checking TSH and free T4 earlier can lead diagnostic and treatment misadventures when levothyroxine dose has been adjusted. C: Increase the levothyroxine dose by 25 micrograms per day and repeat TSH in 2 months.
Now there's something else with this question I want to point out to you that I haven't pointed out to you so far, is you'll notice each answer has two pieces of information in it. So of course we know option C is incorrect because she is biochemically euthyroid and so this is telling us increase the dose and then repeat the TSH in 2 months.
Both pieces of information in an answer have to be right for the answer to be correct for any question. And you might be tempted to say, ‘Well, she feels tired, so let's bump up her levothyroxine dose and see that perk.’ But again, there's no clinical rationale for this since her labs are normal and the patient is telling you why she thinks she's tired.
This is not an unexplained fatigue. Iatrogenic hypothyroidism, where a super physiologic dose of levothyroxine is given, can lead to a number of adverse effects, including bone thinning, increase new-onset atrial fib, and a variety of others. So, in other words, she doesn't need more thyroid hormone. Option D: Repeat the TSH and free t4 today and provide counseling to take the medication with breakfast.
Again, obviously incorrect. The sensitivity and specificity of today's TSA and free T4 are such that when you look at the results, these are the results. Have a nice day. You do not need to repeat this lab. You might run into clinicians who have been in practice for a number of decades, like very often 3 decades plus, which FYI would describe me, and you might hear the incorrect advice that TSH is not that sensitive, not that specific, repeated, etc. That was then, 30 plus years ago.
This has not been true now for a number of years. So, if you've got a TSH and free T4 like we do here that are within normal limits, those are the correct results. No need to repeat the labs. I often hear when I'm coaching people to get ready for boards, particularly coming from the acute care area, that they see labs repeated all the time.
Yes, because that's in the inpatient setting, when your patient is quite physiologically unstable. What we're talking about here is a woman with 10-year history of hypothyroidism. She's been on the same dose of medication for a long period of time, and we're given nothing to make us think there's acute instability. In addition, she's taking the medicine exactly as she should: empty stomach, large glass of water.
And if she was to take the levothyroxine with food, it's going to decrease the amount of levothyroxine that's absorbed. Key takeaway: sometimes on board questions a patient will be actually interviewing really well. And what you need to do is stay the course. In other words, not change therapy. Making the decision to continue with effective therapy for a long-term condition like hypothyroidism is as important a clinical skill to develop as it is to alter therapy when treatment appears to be ineffective.
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