baby's thyroid function

[Fujiko]

my baby's 4months old and from birth the doctors are already monitoring his thyroid function because I have hyperthyroidismbefore I got pregnant. I've been on medication (Neomercazole and Inderal) for more than four years but a few weeks before falling pregnant I stopped taking my medicines because my condition stabilized. It remained stable throughout the pregnancy and until now. But my baby's is not normal. His FT4 is normal but his FT3 is quite high. His TSH is just beyond the normal range. The doctors can't tell why. They say he could have gotten it from me while he was still in my womb. Often he trembles and gets startled very easily which could be symptoms of his high FT3. Yet doctors say that babies do not show symptoms. What do you think?

[Deanna L Aftab Guy, MD]

So yes, there are pediatric endocrinologists especially in australia, there is some of the best endocrine research coming from australia. So, I would have him seen by a specialist or have the levels repeated monthly at least, especially since the last was out of range.

[Fujiko]

He's four months now. The last time the doctors did a blood test was just under a month ago. When should I have him tested again? Are there Baby Endocriologist? I live in Australia. We only see a GP here unless it's an emergency then we go to the hospital where a Paediatrician attends to us. He also looks after the baby's eczema (severe, he's been on oral and topical antibiotics 4x now).

[Deanna L Aftab Guy, MD]

Many times even though a mom has had hyperthyroidism treated prior to her pregnancy we may forget and it is very very important to remember that you carry the antibodies even though your gland has been corrected either by surgery or medication. these antibodies are stimulatory to your gland and also can pass through the placenta to your baby making their little thyroid overactive, sometimes not noted till a few days after birth. Make sure you are followed by an endocrinologist, your hyperthyroidism may indeed be what we call thyroid hormone resistance where the level of thyroid is higher than normal but not suppressing the TSH that regulates it, so both tsh and thyroid are elevated compared to how they should be. It is hard to tell if trembling or startling are related, baby's have a reflex normally called Moro or the startle reflex (some of us adults still have it!)
So his growth is key, monitoring his free and total T4 are more important to me than the T3, the elevated t3 is not necessarily the main thing to follow especially if the t4 is normal, the conversion enzyme is very active and baby's and children may indeed have higher than the lab range of T3 when measured if that is the only thing out of whack on testing.
Go with clinical, is he gaining weight, growing well, eating well, sleeping well, normal bowel movements, did they measure your antibodies such as thyroid antibodies or in the baby thyroid stimulating immunglobulins, you make both stimulatory and inhibitory and this masks the picture in the baby so they may appear to be hyperthyroid and then have hypothyroid, the effect of your antibodies wear off after about 3-4 months so he should be doing better if this is truly neonatal hyperthyroidism due to antibodies from you. Now your condition needs addressed with an endocrinologist and your baby the same. Can you see a specialist where are you located?