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PROPER T3 LEVEL IN PREPARATION FOR SURGERY 6 December 2011 QUESTION-I would like to get your opinion about a patient. I recently saw an 67 year old women referred for preoperative consultation for thyrotoxicosis. She has a valvular heart diease requiring surgical therapy. She has a history of toxic multinodular goitre for last six months. She is a non-compliant patient. She was started on high dosage PTU therapy for rapid preperation for non-thyroidal surgery (Heart valve replacement). While she was on PTU at a dosage of 600 mgr per day, FT3: 5,49 pmol high (2,3-9), FT4: 28,9 pmol normal (9-25), TSH: <0,005 MIU/L . We routinely see such patients during consultation. My question is that both FT3 and FT4 should be normalized before non-thyroidal surgery or FT3 normalisation is enough for safe surgery. Best regards. Alptekin Gursoy, MD Ankara, Turkey RESPONSE- To my knowledge, there is no study on which to base an answer, so my answer is"opinion". Logically T3 levels should be the most crucial, but then T4 is converted to T3 inside many organs. So I suspect both elevated serum T3 and serum T4 levels could contribute to potential trouble, such as arythmias. Preparation for surgery with MNG can be difficult because the glands tend to have a lot of stored hormone, in contrast to the easier depletion in Graves disease. At least you are not yet pushed by a reaction to PTU. Since PTU inhibits T4>T3 conversion, you might have a really effective drop in T3 prior to normalizing T4. So, my guess is that normalizing T3 is most important, and that if T3 is in the normal range, and T4 is not far off, and you have some beta blocker to use or hold in reserve, you should be safe. L De Groot,MD