Our Approach to Thyroid Labs
When it comes to helping you with your thyroid issues, we believe labs are important, but they’re not everything. Learn more about our thoughts regarding lab work–and which ones we’re most likely to recommend.
Q: When I come to see you for thyroid issues, which labs do you look at?
A: I find that a TSH, free T4, free T3, total T4, total T3, reverse T3, TPO antibodies, and anti-thyroglobulin antibodies labs generally give me the information I need.
Each lab gives me one piece of information I’m looking for, so between all these labs, I get a 360-degree picture of what’s going on with your thyroid. I can see:
• whether you have the right amount of hormone in your body
• whether that hormone is being processed correctly into the active form of hormone that helps relieve your symptoms
• whether you have autoimmune thyroid disease, which is known as Hashimoto’s Disease
Q: Do you use the labs to make the diagnosis of hypothyroidism?
A: While labs can help make the diagnosis of hypo- or hyperthyroidism, they need to be considered alongside a careful assessment of your symptoms.
I joke that on the first day of medical school, they told me to treat the patient, not the lab value. Then they spent the next 7 years of my life trying to convince me to treat the lab value. As you know, though, labs rarely tell the whole story. That’s because you are not your labs.
For example, if you are feeling cold, tired, dry, constipated, depressed, and overweight, I don’t need the labs to tell me that you are hypothyroid. Other symptoms such as joint aches, foot pain, thinning eyebrows, thinning hair, forgetfulness, hives, skin rashes, and difficulty swallowing can help make the diagnosis as well.
Q: Do you look at ranges in labs or optimal levels?
A: I’ve been treating thyroid disease intensively for over a decade now, so I have developed my own optimal levels based on what I have seen works well for thousands and thousands of patients.
Those levels, interestingly, are clearly different from the standard way of looking at thyroid labs, but even can be different from other, effective thyroid specialists.
I’ve found over the years that a free T3 level toward the top of the normal range (over 3.2 in most labs) is the best predictor of feeling well. This is frequently accompanied by T4 levels toward the lower part of the normal range and reverse T3 in the middle to lower part of the normal range.
I have a large capacity to tolerate a low TSH if you are feeling well (though we always have to go over the risks and benefits of a low TSH), but I generally discourage T3 and T4 levels far outside the bounds of normal as this can be associated with complications such as osteoporosis and atrial fibrillation.
Many patients I have met over the years can feel well with a free T3 toward the top of the normal range or just slightly above as long as the reverse T3 is on the low side. That T3/reverse T3 ratio often (but not always) predicts who is feeling well and who is not.
Q: Do you use the labs to base your decisions on therapy?
A: The labs definitely help guide the therapy, especially when the clinical picture is unclear, but I get more information from you than from the labs.
As I have been saying, I get some information from the labs, but I get even more from you. If you are feeling well, there is a very, very high chance I will not change the medication or doses. Conversely, if you are feeling poorly, I will do everything I can to help you feel better even if the labs are spot-on perfect.
Q: Do you look at other labs as well?
A: Depending on the situation, I may look at nutrients, adrenal function, or other hormones.
I sometimes look at labs for nutrients such as iron/ferritin, B12, D, copper, and zinc. Also, if people are not feeling well and can’t tolerate enough thyroid medication to raise their numbers, I will evaluate adrenal function with serum or saliva testing. For women in menopause or perimenopause, it’s not unusual for me to look at hormones such as estrogen, progesterone, and testosterone as well.
Q: How often do you check labs?
A: Remember, the labs give some information, but you give me more information.
Thus, if we change doses or medication, when you follow up with me, I will talk with you to find out how you are feeling. Oftentimes, I get enough information from you to make a decision about the best next course of action.
That said, the labs can help guide therapy, especially if it’s not entirely clear if you’re feeling better. In my experience, it takes about 4 weeks for hormones to regulate after a medication dose change. Frequently, at the beginning of working together, I will order labs every 4-6 weeks and meet with you to review the results. Waiting 6 or 12 months if you’re not feeling well is much too long.
Note that I always want labs done in advance of the next appointment, so we can review the results along with how you’re feeling. Once you’re on a stable dose of medication and are feeling well, most patients will have labs done every 6-12 months, though a few patients like to keep a closer eye on their levels and request that labs be drawn every 3 months. For your own safety, we require that everyone have labs drawn at least once per year.
I hope this has given you a good idea of how I will work with you to get you feeling better and resolve your thyroid problems.
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