A 3rd follow-up on Newborn with Low Normal T4 and High TSH

[ttyy]

Dear Dr Guy,

As you asked me to remind you of the baby's age and suggested a repeat of TSH along with FT4. The baby is now 50 days old. I found out the mother ignorantly was using amply povidone iodine on her baby (all over the body including the neck, armpits and between the legs, …)  instead of a baby powder for the 1st 43 days of the baby's life. Therefore, I strongly suspect it was this iodine exposure behind all this trouble. The other suspicion I have is that the mother herself might be subclinically hypo but she is quite slim and normal apart from sleeping most of the time. We can't afford the tests for the near future. Hypothetically if that was the case,  would anti-bodies (anti-TPO and anti-TG) transfer to the baby through the breast-milk?  As a pre-measure we moved the baby largely to formula one week before the final test and of course povidone iodine was stopped at the same time. The baby's general health got better and started to gain weight very quickly. But I am worried that the gain in the baby's face is a sign of hypo  rather than a healthy growth.

We also did  thyroid USG at the 42nd day which seemed quite normal.

Here are the test results:

Age: 50 days
TSH: 12.6 uU/ml   (lab ref range 1.7-9.1 for 2-20 weeks) and ( 0.7-6.4 for 5mo-2yr)
FT4: 1.11 ng/dl      (lab ref  range 1.1 – 3.0 infants)  and (1.6-3.8  newborns)

Age: 37 days
TSH: 17.5 uIU/ml (lab ref range up to 20 for newborns) and (0.49-4.7 adults)
T4: 9.88 ug/dl (lab ref 6.5-27 newborns) and (5.4- 13.8 infants)


Age: 36 days (different lab)
TSH: 28.5 uIU/ml (lab range 0.5-6.0)
T4: 7.4 ug/dl         (lab range 7-14)

The baby was born preterm at the end of 8th month and start of the 9th . His weight back then was not measured but seemed to me very low weight <1.5 as a guess.  His weight now is normal.


What would be your final diagnosis and advices?

Kind regards

[Swan421]

A related discussion, My 5 year old has an elevated Free T4 was started.

[ttyy]

Dear Deanna,

I felt the need to update you with the final results.

My baby nephew's TSH thankfully returned to normal without any treatment at all during his 72 days of life. At physical examination the baby is quite normal.

Here is the TSH (sensitive) test results:

Age 72 days:
TSH : 1.62 uU/ml (lab ref range 1.7-9.1 for 2-20 wk)

With gratitude.

[ttyy]

Thank you Deanna.

[Deanna L Aftab Guy, MD]

given this unusual history of iodine exposure it is more than likely the cause-iodine is needed in the production of thyroid hormone, it is also used as a topical wound cleanser and antibiotic like substance(preoperatively as well) but chronic use on a daily basis is very rare and not expected. The iodine use can lead to goiter and rise in tsh.  I would monitor the tsh now off of treatment, it looks like the tsh is coming down.The free T4 remains normal. Repeat labs should probably be in 1-2 months as long as pediatrician is following growth and development overall. the antibodies that are related to hashimotos would not be affected via breast milk, rather via blood such as in utero, therefore I would not be concerned at this point with the antibodies.