I have been taking 100 mcg thyronorm since 8 years. Very recently on arpil 19 2023 I took the tsh sensitive test and my tsh level was 0.20 uiu/ml. And the doctor mentioned that your is too low indicating too much thyroid medication. I am now taking 75 mcg my question is that tsh 0.20 uiu/ml is considered as overactive thyroid, so why is that the doc has prescribed of levothyroxine? Please advise as I am confused now.

Dr. Prabhakar Laxman JatharEndocrinologist52yrs exp

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Hello, thanks for the query. Madam, I have seen the details mentioned. When one is on adequate dosage of levothyroxine tsh is maintained around 2 to 4 mu/l (lab range may vary from 0.5 to 5 mu/l or up to 4.5mu/l). When one is taking a higher dosage for some time then t4 levels may go up and tsh level may go below the lower limit of lab value. As it has happened in your case. In this situation reducing the dosage will make tsh level remain with in the specified range. Hyperactive thyroid is considered when tsh goes < 0.05 mu/l & simultaneously t4 goes beyond the upper limit (which may vary from 12 to 14 ug/dl in different labs). When that happens then one has to stop taking levothyroxine for some time till the values return to normal range. In your case because of higher dosage tsh has become low. So by taking 75 mcg it will return to the desired range. You will have to check the levels after 6 weeks of changing the dosage. If you have any questions do come back. Thanks.  

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