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Thyroid Diseases

Fluctuating TSH - Are These Levels Significant?

10/22/2007

Question:

TSH- 0.36 (normal 0.34-4.82) T3 free- 4.34 (2.77-5.27) T4 free- 1.06 (0.71-1.85) Gyn doc reviewed and stated a little low lets pull TSH again in 4-6 wks just to make sure.

Pulled again in 6 wks: TSH- 5.66 (0.34-4.82)

A little history-- I had visited my gyn for annual exams in 7/2007 and discussed with him about trying to get pregnant. Stopped birth control pills in 1/2007 and menses had gotten lighter (5-6 days to 2). Also I have noticed a significant sweating increase, decreased/no libido, difficulty sleeping, fatigue

I take no medications, no health history, labs pulled same time of day, no lifesytle or diet changes, etc.

What will make the levels change so much? Or is this considered a "significant" change?

Answer:

These abnormalities (actually the initial TSH isn't even abnormal) are quite minor. It is possible that you have had a mild, self-limited inflammation of the thyroid gland. This could give you a few weeks of months of a low (or low normal) TSH followed by a few weeks or months of a high TSH. Also, your immune system might be making a combination of antibodies that both stimulate and inhibit the thyroid gland, and the levels of those antibodies might be changing. On the other hand, the abnormalities are so slight that they might not represent any disease at all. Since the free T4 and free T3 are normal, I doubt that any of your symptoms have anything to do with your thyroid gland. I wouldn't start any treatment at this time. I would wait another 2-3 months and repeat the TSH, free T4, and free T3.

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Response by:

Thomas A Murphy, MD, FACP, FACE Thomas A Murphy, MD, FACP, FACE
Associate Professor of Medicine
School of Medicine
Case Western Reserve University