Borderline thyroid tests: When should you take thyroid medication?

January 27, 2011 58 Comments by Scott Isaacs MD

A recent study found that many people have untreated thyroid disease.  The study, published in the Journal of Medical Screening assessed over 4000 people between the ages of 50 and 65 and found about 8% have low thyroid levels.  When weight goes up, many people suspect a low thyroid.  But when they go to the doctor, they get the routine “TSH” test and are told “it is borderline” and probably not the problem.  As an endocrinologist, I see this frequently.  There are so many cases with borderline thyroid testing where the thyroid really was to blame.  Once treated, thyroid patients lose a lot of weight without a major change in their diet or exercise routine.

Thyroid experts recognize the TSH test as the test of choice when thyroid disease is suspected.  An elevated TSH test diagnoses hypothyroidism.  TSH is more sensitive than other thyroid tests because it begins to rise before thyroid hormones drop.  As such, it’s a better indicator of early thyroid dysfunction.

When the TSH test is “high normal,” in the range of 2.5-4.5, deciding to take thyroid medication can be a difficult decision.  I’ve seen many patients with this situation.  Frequently, thyroid tests in this range will normalize within a few months, other times, they progress to overt hypothyroidism.   The first step is to repeat the test.  I never make a treatment decision based on a single blood test.  Experts recommend waiting 3 months to repeat a borderline abnormal TSH test, but if you have a lot of symptoms it is better to do it sooner.

In my opinion, many doctors take the easy way out and prescribe a low dose of thyroid medication when the thyroid is really normal.   If you take low dose thyroid hormone and your thyroid is normal, it will make fewer hormones to maintain normal levels.  So taking a low dose of thyroid hormone, even if you don’t need it may not do much.  I’ve seen so many patients who have tried this approach and then come to me still complaining of symptoms.  Some of these patients stopped thyroid hormone replacement and felt better.  Others do feel better, but I have always wondered how much of this was placebo effect?  A study was done to determine if treatment with thyroid hormone could improve the symptoms of hypothyroidism in people with normal thyroid function tests.  The results, published in the British Medical Journal, showed that thyroid hormone was no more effective than placebo for relieving symptoms.

On the other hand, some people with borderline tests have early thyroid disease that is certain to progress.  Diagnosing hypothyroidism in the early stages can be tricky.  That’s because when the thyroid starts to fail, tests can remain in the normal range for a period of time.  The first thing that indicates low thyroid is an elevated TSH level.  A change from a low normal TSH to a high normal TSH over a period of a few months may mean early thyroid failure.  If thyroid antibodies are positive or if the thyroid gland is enlarged the risk for thyroid failure is extremely high.  If the thyroid antibodies are normal and the thyroid is not enlarged, the risk is much lower.

The bottom line is that many times there is no easy answer.  If the thyroid is truly to blame, tests will become more clearly defined as time goes on.  There is usually no harm in waiting a few months to make a decision about treatment.

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  1. Laura says:
    Tuesday, March 25, 2014 at 1:40pm

    I have had my TSH checked over the last 5 years as part of my physical it is everything from 4.80 – 7.6, they also looked at my T4 twice which was still in a normal range. My question is do you see variability in TSH level, seems like it is all over the place up and down in the range started above? I am 54 and post menopausal, having symptoms like fatigue, depression, brain fog, decreased libido, loss of words, but no issues with weight gain or constipation. I have however had an episode of GI reflux that has been challenging. Endoscopy is normal. My gyn wants me to try a low dose synthroid for my symptoms, and my pcp is more a retest some more. I am almost at the point where I need to take antidepressants. do you see this up and down with the TSH? Is this predicting that my thyroid is going to give out and I should just take the synthroid over a dose of an antidepressant. My symptoms are not terrible, just annoying and if I could feel better it would be nice!

  2. Scott Isaacs, MD says:
    Tuesday, August 19, 2014 at 7:51am

    I advise working with an endocrinologist. Your levels are borderline low and may need treatment. However, some people will normalize their thyroid levels without taking medications. It is a clinical decision you need to make with your doctor.

  3. Maureen Goldfuss says:
    Sunday, February 22, 2015 at 1:05pm

    My test results were T3=59; T4=3.7 ; TSH-3rd generation = 31.61;
    Back in 1991 I had radio active iodine because I had on interactive thyroid. Since then I have always taken synthroid. This last test shows that my thyroid is not at a normal range. I have been treated for Major Depression and I believe my thyroid has something to do with it.

  4. Debbie says:
    Monday, March 23, 2015 at 7:07pm

    I am 58, I’ve been on antidepressants 20 years, had em balanced hormones and many thyroid test. My Adrenal gland number was down to 2.9-3.01. I was on Cortisol for. One year. Always being in normal elevated numbers was frustrating. I haven’t been able to loose weight for 5 years even at 1400 calories. My waist size has increased and I feel terrible. On top of that I’ve waited 2 years for back surgery for disk fusion from SL 5 to the last L in the spine. I just want my life back. My new blood work showed my thyroid count at 6.66. I’m trying to find a new Endroconologist. Could this be the reason for extra weight, fatigue, and more depression?

  5. Leeanne Tyler-Olsen says:
    Wednesday, September 9, 2015 at 4:25am

    Hi Debbie,

    Just read you post. I am 59 & was diagnosed with Hashimoto’s 5 years ago. I’ve also been on antidepressants for 18 years & had fusion surgery & a disc replacement 31/2 years ago. We have a lot of similarities! I am now seeing a group of holistic doctors who recommended that I change my diet, which I have done. No gluten, soy, dairy or sugar. I am feeling much better than I was a year ago. I would recommend a book called: “Hashimoto’s Thyroiditis: Lifestyle Interventions for Finding & Treating the Root Cause” by Isabella Wentz. Isabella suffers from Hashimoto’s & has done a huge amount of research into the disease. Most GPs don’t have a clue about this & won’t know about the appropriate lifestyle interventions, nor how test results don’t give the full picture. If your results are “Euthyroid”, this doesn’t mean that there isn’t a problem. Hashimoto’s is a complex disease & is related to other autoimmune conditions, especially coeliac disease. Find yourself some really good doctors or a good endocrinologist who can sort things out for you. I hope you feel better soon! Best wishes, Leeanne from Oz.

  6. Jeff says:
    Saturday, November 21, 2015 at 1:27am

    TSH 7.6
    Triyodotironina TOTAL 67.5

    (T3 libre 2.4)

    Everything else normal. I generally feel like hell.

  7. Erica says:
    Tuesday, January 26, 2016 at 11:54am

    Once you start taking Armour Thyroid are you on it for life? I am borderline and was prescribed by a doctor other than my FP Doctor. My FO Doctor is mad I am on it and says if I take it for 6 months I will be on it for life because my thyroid will stop working because my Brady has the hormone from the pills.

  8. Scott Isaacs, MD says:
    Thursday, February 11, 2016 at 5:15pm

    If you really need it, it is for life. If you don’t need it you shouldn’t take it. I recommend that you see an endocrinologist who is familiar with The Endocrine Society Guidelines for the Management of Hypothyroidism.

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