The Thyroid Lab Tests to Ask For

by JJ Virgin on June 6, 2023

Been called normal lately? It’s not the worst thing someone could say—unless they’re talking about your thyroid labs. That’s because in the U.S., our current standard of “normal” is way too huge a range.  

Healthcare professionals can cling to that normal range and brush off patients whose thyroids actually aren’t functioning as well as they could, leaving them without the care that will help boost their overall health. 

I want you to be better than normal. I’m going to share with you the lab tests you can ask your doctor to perform to get to the bottom of your symptoms. These labs will give you a comprehensive picture of how your thyroid is operating in tandem with the rest of your body, and highlight the impact your thyroid health can have on your wellbeing.  

Symptoms of an Underactive Thyroid 

First, let’s talk about some of the signs that your thyroid is underactive. If you’ve recently (or even not so recently) heard from your doc that your thyroid levels are “normal,” you might not have realized that some of these symptoms may indicate that your thyroid could be working much better for you:  

  • Unexplained weight gain: Your thyroid is in charge of how fast or slow your metabolism goes. So if your thyroid is underactive and not producing enough thyroid hormones, your metabolism slows down and doesn’t burn as much energy as a faster metabolism would. This means that diet and exercise routines that once worked for you to maintain your weight just don’t seem to work any longer.  
  • Feeling fatigued, sluggish, or just a bit ‘off’: Your thyroid can impact energy levels in a few different ways. A slower metabolism is one—it can minimize the energy being pumped to your brain, leading to feelings of sluggishness or trouble focusing. Plus, a hormonal imbalance can impact serotonin levels. Without optimal production of the hormone that plays a role in your mood, it’s common to feel ‘off’ or even uncharacteristically depressed because of hypothyroidism.1 
  • Brittle or dry nails, hair, or skin: When thyroid hormones are imbalanced, it can throw off the balance of other hormones in your body, too. Without enough hormones working as they should, your body might not produce enough keratin and sebum, which impact the strength, health, and moisture in your nails, skin, and hair.2,3 If you have noticed any of these symptoms, my Collagen Peptides Powder helps support skin health and hydration. Adding a scoop of this powder to loaded smoothies, coffee—just about anything!—is a super easy way to support a healthier appearance, and boost your confidence and your metabolism.* 
  • Increased sensitivity to cold: Everyone can get chilly at times, but if you’re finding that you’re much colder than everyone around you, or feel cold at a temperature that never used to bother you, it could be an indication your thyroid isn’t working optimally. When your metabolism slows due to an underactive thyroid, it becomes more difficult for your body to keep up with temperature regulation. 
  • Constipation: A slower metabolism and hormonal imbalance can play a role in slowing down your digestive system. Waste has a tougher time making its way through your digestive tract, leading to constipation.  

The Types of Thyroid Tests to Ask For 

Feeling even one of these symptoms lately? Get in touch with a functional medicine doctor, and ask them to run these labs to get a comprehensive picture of your thyroid health:  


TSH stands for thyroid-stimulating hormone, and this test indicates how much thyroid hormone your pituitary gland is creating. This is the standard test that a healthcare provider will take to measure how hard your thyroid is working. And while it is an important piece of the puzzle, it is not the only piece. Plus, most providers believe that TSH levels anywhere from 0.5-4.0 are normal, which I believe is far too big of a range.  

  • My pal Dr. Izabella Wentz, who specializes in thyroid health, thinks that most people function best when their levels are between 0.5-2.0.   

Free T3 

T3 refers to triiodothyronine, your active thyroid hormone that regulates metabolism. This hormone typically binds to protein, but some remain “unbound,” or free. Those free T3 are the ones that can trigger physical processes in your body, so it’s important that your body maintains enough free T3.  

By learning how much free, unbound T3 you have, you can ensure the balance between the two is where it should be.  

  • A normal level of free T3 level is considered 260-480 pg/dL.  

Free T4 

This is similar to the T3 test, though this test measures free thyroxine, or Free T4. This type of thyroid hormone often works in conjunction with T3. It helps regulate important bodily functions like metabolism, and cell growth and development in areas like digestion, bone strength and muscle health.  

Like T3, most T4 binds to proteins, but others are free to enter cells and trigger action. Looking at the free levels of T4 in your body helps to check that the balance between them is optimal.  

  • A normal level of free T4 is considered .8-1.8 ng/dL. 

Reverse T3 

Your body needs to convert some of its T4 into T3. But if it notices that both your T3 and T4 supplies are too low to efficiently convert T4, it will start to divert your T3 into what’s known as Reverse T3. This is an inactive, and therefore ineffective form. High levels of Reverse T3 could indicate your body is having issues converting T4 into a more optimal form.  

  • A normal level of Reverse T3 is considered 10-24 mg/dL. 

Thyroid Antibodies (TPO & TG) 

There are tons of different types of antibodies. Many go to work attacking things like bacteria, viruses, or fungi in your body that are making you sick, and they play a critical role in helping you recover from illness. But other times, you can create certain types of antibodies that mistakenly identify something as hostile and go to work attacking what your body actually needs.  

Thyroid peroxidase (TPO) and thyroglobulin (Tg) are two such antibodies. They can attack your thyroid to the point where it won’t function well enough to produce a balanced amount of thyroid hormones. High levels of either can be an indication your thyroid issues stem from an autoimmune condition, and a sign you have Hashimoto or Graves’ disease.  

By identifying these levels, will doctor will be able to suggest changes that help you create a more functional immune system in order to keep those antibodies from attacking. Diet often plays a huge role in that treatment. Even if you’re not sure if your thyroid issues stem from an autoimmune condition, you might find it helpful to listen to my guide for some of the foods that help support Hashimoto’s and see if you start feeling better after making some swaps. 

  • A normal level of TPO is considered less than 35 IU/mL and a normal level of Tg for women is considered 1.5-38.5 ng/mL. 


This is an important test, since it can showcase an underlying iron deficiency and subsequent thyroid problem, even if other indicators of iron and thyroid like red blood cell count and T3 are coming up as “normal.” That’s because T3 needs ferritin to get to work. Low levels of it could signal to your doctor that including iron (or iron-absorption measures) into your treatment plan would help boost your overall thyroid health.  

  • A normal level of ferritin in women is considered 12-150 ng/mL.  

These are all tests that can be done with a simple blood draw. With this more specific lab reading, a functional doctor can accurately assess the root problem of your thyroid issues and come up with a treatment plan that holistically restores your thyroid health. They may suggest a combination of medication, diet, and lifestyle changes that can help you move beyond normal and into the optimal person you’re meant to be.  

If your healthcare professional isn't able to offer you these labs, you can order an advanced thyroid panel directly from my friends at YourLabwork.* It's so easy. You can order your tests online, get a blood draw near you, and learn your results just 48 hours later.

Once you have your results, my Metabolism Rescue Program is a great way to jumpstart a lifestyle reset. Through a multi-pronged approach to boosting your metabolism, you’ll start to recognize the diet changes that allow your thyroid to keep your metabolism in gear. Plus, the nutrient support you’ll get can go a long way towards correcting the changes you may have body composition, mood, appearance, and more.**

Learn more and enroll in the program here


  1. Bauer, M., Heinz, A., & Whybrow, P. C. (2002). Thyroid hormones, serotonin and mood: Of synergy and significance in the adult brain. Molecular Psychiatry, 7. 1 
  2. Radoja, N., Stojadinovic, O., Waseem, A., Tomic-Canic, M., Milisavljevic, V., Teebor, S., & Blumenberg, M. (2004). Thyroid Hormones and Gamma Interferon Specifically Increase K15 Keratin Gene Transcription. Molecular and Cellular Biology, 24(8). 15 
  3. Ramot, Y., & Paus, R. (2018). Neuroendocrine Controls of Keratin Expression in Human Skin. IntechOpen. doi: 10.5772/intechopen.80406 

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**These statements have not been evaluated by the Food & Drug Administration. Products mentioned are not intended to diagnose, treat, cure, or prevent any disease.