Lab Tests Every Thyroid Patient Needs (On Top of Thyroid Labs)

Yes, thyroid lab tests are important and they are something you need to pay attention to.

But more important than your thyroid function lab tests are the tests for things like your nutrient status, cholesterol, blood sugar, and other hormones.

Why?

Because they give you a ton of additional information about how your thyroid is impacting your body and because they are often a missed cause of lingering thyroid-like symptoms.

It’s for these reasons that I recommend thyroid patients get all of the following lab tests on top of their standard thyroid lab tests:

#1. Serum Magnesium or RBC Magnesium

It doesn’t matter which type of magnesium you are checking here just make sure that you check it. 

You will see a recurring theme here as it relates to magnesium, vitamin B12, and folate in that these tests are not super accurate. 

But even though they are not 100% accurate, you should still be ordering them. 

Why?

While they may not tell you if these nutrients are perfectly optimized, they can let you know if you are grossly deficient.

Understanding your magnesium level is important because magnesium is required by the thyroid for several functions (1) including bringing iodine into the gland for creating thyroid hormone.

That and the fact that both stress and thyroid dysfunction can accelerate magnesium loss in the urine.

For these reasons, thyroid patients often benefit from supplementing with extra magnesium.

You don’t necessarily have to test your magnesium level prior to supplementing with it, by the way, but it’s not a bad idea to grab it if you can.

In terms of accuracy, RBC magnesium is said to be slightly more accurate than serum magnesium but, in my opinion, it doesn’t matter which one you get because you can still have a ‘normal’ level and still benefit from taking it.

So, when in doubt, err on the side of supplementing regardless of what your labs show.

#2. Vitamin B12

Vitamin B12 is another important nutrient and many thyroid patients end up deficient in it.

Depending on which study you look at, it’s found in 30 to 50% of hypothyroid patients (1)!

What makes this problem more concerning is that serum B12 testing is rarely accurate which means there are plenty of hypothyroid patients walking around with less than optimal B12 without realizing it.

But, similar to magnesium, it’s still worth checking your B12 status because, even though it’s not very accurate, you can still catch very low B12 levels from time to time.

Your B12 status is important as a thyroid patient because B12 deficiency can lead to hypothyroid-like symptoms such as fatigue and brain fog that often complicate thyroid management.

You may run around wondering why your thyroid symptoms are so hard to treat when the reality is your symptoms are coming from your B12 status, not your thyroid.

It’s for these reasons that it’s a great idea for hypothyroid patients to proactively supplement with vitamin B12 using a pre-methylated form like methylcobalamin or adenosylcobalamin (and throw in hydroxycobalamin for good measure).

#3. Folate

Folate, also known as vitamin B9, helps your body create methionine which is used as a methyl donor for many different reactions in the body.

And research has shown that up to 34% of patients with subclinical hypothyroidism are deficient in it (1).

We can safely assume that this number is probably much higher in patients who have clinical hypothyroidism.

Given its important role in regulating many functions in the body, and the relatively high rate of deficiency, checking for it is a no-brainer.

But like vitamin B12 and magnesium, it’s probably best to just err on the side of caution and preventively supplement with a multivitamin that contains all three.

#4. 25 Hydroxy Vitamin D

Unlike magnesium and vitamin B12, testing for vitamin D is actually accurate and quite useful!

As a thyroid patient, vitamin D protects your thyroid gland by keeping autoimmune diseases at bay and by helping to prevent thyroid cancer.

That’s just the benefit to your thyroid, from a general health perspective, vitamin D helps prevent depression, fatigue, GI issues, and even autoimmune disease (3). 

Testing for vitamin D status is a necessity if you have any type of thyroid condition simply because of the high rate of deficiency that exists among everyone and because of how important it is for protecting your thyroid gland.

There are several ways to test your vitamin D status but the one you want to get is called 25-hydroxyvitamin D.

Check this level and, if needed, supplement with vitamin D3 to raise it.

For most thyroid patients, a dose of 2,000 to 10,000 IU per day will improve your status considerably but more aggressive measures may be necessary if you are overweight.

#5. Serum Fasting Leptin

If you are one of the roughly 70% of hypothyroid patients who struggle with the inability to lose weight then checking your serum leptin is a good idea.

Leptin is a hormone secreted by your fat cells and acts as a message to your brain of long-term energy supply or total fat mass.

As you gain weight, your body will produce leptin which is supposed to act to help you burn that fat.

If your leptin remains high but you are unable to lose weight, you have a problem with leptin signaling and are said to have leptin resistance.

Leptin resistance can be easily tested for by checking a fasting serum leptin.

#6. Serum Fasting Insulin, Hgb A1c, and Blood Glucose

These tests are all designed to assess for one thing:

Insulin resistance.

They are all important and give you a little bit of different information. 

High insulin in the fasted state is probably the strongest indicator of insulin resistance but it’s still important to assess fasting glucose and hemoglobin A1c.  

Thyroid patients are at increased risk for developing high blood sugar and diabetes which is why these are included.

#7. Serum Estradiol

Estradiol is the most powerful estrogen and is important for both men and women.

The reason we care about this sex hormone is because thyroid hormone impacts both estrogen and progesterone which can lead to problems such as infertility, anovulatory cycles, irregular menstrual cycles, and decreased sex drive.

Checking your estradiol is an easy way to assess how your thyroid is impacting your sex hormones and may explain things like why it’s difficult for you to lose weight or why you are experiencing certain symptoms instead of others.

The serum estradiol isn’t necessarily the best way to assess estrogen status, but it can give you helpful information which is why it’s included here.

Just be aware that factors such as whether you are regularly menstruating and whether or not you are menopausal or perimenopausal all impact how you should interpret your results.

Most thyroid patients who assess their estrogen will likely find that their estrogen is relatively high and their progesterone is relatively low putting them in a state of relative estrogen dominance.

#8. Serum Progesterone

Serum progesterone pairs perfectly with serum estradiol so if you are going to check one you need to check the other.

Progesterone acts as an antagonist to all of the actions of estrogen which is why a balance of both is important.

Many thyroid patients will find that their progesterone is low which can be easily managed with natural treatments or with over-the-counter bio-identical progesterone cream.

But you obviously don’t want to take it unless absolutely necessary which is why you want to get this test.

#9. Free and Total Testosterone

Testosterone levels tend to be another casualty of thyroid disorders. 

Many women with hypothyroidism, especially if they have Hashimoto’s, will find that their testosterone is low.

In order to assess testosterone status, you’ll want to get two tests:

• Total testosterone
• Free testosterone

If you find that one or both of these metrics are abnormal then you can take appropriate steps to correct the problem.

For many thyroid patients, especially women 40 years or older, you will most likely find that your testosterone is low.

Symptoms of low testosterone in women usually include things like the inability to gain muscle mass, the inability to lose weight, irritability, and decreased libido. 

The symptoms are similar for men but are much more pronounced as testosterone tends to provide more influence on men than women.

Treating low testosterone should always start first by treating your thyroid but you also have the option of taking testosterone creams and gels which work very well for both men and women.

#10. Sex Hormone-Binding Globulin (SHBG) 

Sex hormone-binding globulin is another tool that can actually give you important insight as to how your body is tolerating thyroid medication.

SHBG is secreted by the liver and only in response to two hormones:

Estrogen and thyroid hormone. 

Given this, a low SHBG in the serum is either caused by liver problems, low estrogen, or low thyroid.

SHBG isn’t a perfect way to measure thyroid function, but it can provide valuable insight to thyroid patients who continue to experience low thyroid symptoms despite having normal thyroid labs.

If you find that your SHBG is low, it should increase as you take thyroid medication.

If you are not then this is a sign you are either not converting your medication appropriately (indicating a problem in T4 to T3 conversion) or that your medication is not being absorbed (indicating a problem with the gut).

Don’t neglect this test!

#11. Serum Cortisol (8 am)

Cortisol is the major stress hormone produced by the body and tends to become dysregulated in thyroid patients (1).

It’s far from a perfect test in assessing what people refer to as adrenal function because you can very well experience significant fatigue despite having normal cortisol, but it does provide helpful information.

Having a normal serum cortisol doesn’t rule out adrenal fatigue but it does rule out the more serious cortisol-related conditions like Addison’s disease (adrenal insufficiency) and Cushing syndrome.

There are many ways to test your cortisol but don’t get fooled into thinking you need to pay for expensive salivary, urinary, or hair tests.

A good old-fashioned serum cortisol will do the trick for the majority of people and provide you with all of the information you need.

If your cortisol appears to be normal but you are experiencing the classic symptoms of adrenal fatigue then you can start treating with adrenal adaptogens, adrenal glandulars, and other stress-reduction techniques.

#12. Iron Studies (ferritin, serum iron, TIBC, % saturation)

There exists a strong connection between your iron levels and how well your thyroid can function. 

Thyroid peroxidase, the enzyme required for creating thyroid hormone, requires heme or iron to function.

So when iron is low, your body will have a difficult time creating thyroid hormone.

To complicate matters further, the low thyroid state results in decreased absorption of iron.

This vicious cycle can spiral out of control quickly if you don’t intervene which is why you always want to keep an eye on iron levels as a thyroid patient.

You can do this by looking at four lab tests:

• Serum iron
• TIBC
• % saturation
• Ferritin

Pay very close attention to your ferritin because ferritin is also required for hair growth and is a principal cause of hair loss among thyroid patients.

#13. Cholesterol Studies (HDL, LDL, and total cholesterol)

Because thyroid hormone regulates the creation of cholesterol, high cholesterol and thyroid dysfunction (5) often go hand in hand.

In fact, the impact thyroid hormone has on cholesterol is thought to be one of the main reasons that thyroid patients have higher mortality rates compared to the average population.

There are plenty of causes of high cholesterol that are unrelated to your thyroid but, and this is a big but, if you have a thyroid problem and you have high cholesterol, you better prove that your high cholesterol isn’t solely related to your thyroid.

Because if it is, it’s 100% reversible.

Most doctors are trained to look for reversible causes of high cholesterol but they often rest on their laurels given that, statistically speaking, high cholesterol is almost always related to lifestyle choices.

For this reason, thyroid patients should always keep an eye on their cholesterol panel.

#14. Comprehensive Metabolic Panel

The comprehensive metabolic panel, also known as the CMP for short, is a set of tests that evaluate your liver, kidney, and electrolytes.

This is a standard lab test that your doctor has probably evaluated on your behalf several times, but just make sure you get it.

#15. Liver/Kidney Function (Creatinine and AST/ALT)

The CMP contains this information so you don’t need additional tests, but here’s why it matters for thyroid patients:

AST and ALT are sensitive markers of live function and can tell you whether or not this important organ is experiencing damage.

If your ALT and AST are elevated then this is a bad state for your thyroid because much of your T4 is converted into T3 in your liver.

Elevated AST and ALT are frequently associated with a condition known as fatty liver disease which is a sign of insulin resistance.

Obtaining information about your liver can therefore give you information about your insulin status and your ability to properly utilize T4 thyroid hormone.

#16. Inflammatory Markers (ESR, CRP, and Ferritin)

These inflammatory markers help you understand if there is systemic or generalized inflammation in your body. 

They are easy to test for and easy to order. 

The ones you want to look at include ESR (which stands for erythrocyte sedimentation rate), CRP (which stands for C reactive protein), and ferritin (which is an iron study but can double as an inflammatory marker as well). 

If inflammation is present then it poses a problem for your thyroid because inflammation negatively impacts T4 to T3 conversion. 

The best way to manage inflammation is by searching for the source but if you aren’t able to locate it, or you just want to take a shotgun approach, you can often blast inflammation away with anti-inflammatory supplements.

#17. Autoimmune Markers (Thyroid antibodies such as TgAB and TPOab)

You would assume that these thyroid-related antibodies would be ordered by most doctors, but you’d be wrong.

Most doctors fail to recognize their importance because they don’t believe their presence changes treatment.

But from the patient’s perspective, they are critical because you can often positively impact them with natural therapies.

For this reason, you will want to test for these antibodies periodically.

If you have never tested before, then get a baseline level that you can look back on.

Thyroid patients are also at increased risk for developing other autoimmune diseases (6) such as type I diabetes, multiple sclerosis, vitiligo, rheumatoid arthritis, and so on, so you may want to test for antibodies corresponding to these diseases if you have lingering symptoms after completely addressing your thyroid.

Takeaways

Remember:

These tests should always be ordered in conjunction with your thyroid lab tests! 

These do not replace your thyroid lab tests but should be used in conjunction with them. 

Also, you don’t need to get this work-up every time you get your labs drawn. 

But if you’ve never had this type of work-up in the past, or if you aren’t sure what is going on with your body, then it’s a great place to start. 

Now I want to hear from you:

Have you had a complete work-up in the past?

If so, what things did you find?

If not, are you going to get it done?

If you have any other lab tests that you’ve found to be helpful in your journey please share them below as well!