I have a pregnant lady with history of Grave's dse s/p RAI before her first pregnancy. This is her second pregnancy and she is on her 2nd trimester. I have her on Synthroid and her TSH levels have been at 1-1.5uiu/ml. I ordered a TSI and it is mildly elevated at 146 %(<=125% Quest lab) . On her first pregnancy, her TSI was normal at 81%. Clinically she is ok but I'm not sure if I have to start her on PTU plus synthroid because her TSI is high and I worry about fetal hyperthyroidism. What do you think? Thank you.
Maria Mercado, MD
Overland Park, KS 66213
You are correct in being concerned since the TSAb level is significantly elevated. However,the exact TSI level at which the fetus would be in danger is not certain. I think a consensus position at this point would be to not institute PTU therapy, but to follow the patient and TSI closely, and check the fetus by US for signs of hyperthyroidism, growth abnormalities,and goiter. It would be interesting to hear from you again as the pregnancy progresses.
L De Groot, MD