Infant with Genetic Problem and Hypothyroidism

Question

Dear Sirs:

First of all thank you very much for your help.

I have been consulted for a 3 year old boy whowas born from un uneventfull pregnancy and delivery with an APGAR score of 1/8. TSH was informed as normal in neonatal screening and a TSH levelof 6.54 mu/l was foundat two months of age. When he was 1 year old another test was done because of developmental delay. TSH in that opportunity was 8.68 with a T4 of 11ug/dl. A pediatric endocrinologist repeated this exam and TSH was about 2.55, T4 11, Free T4 1.16. So, no treatment was indicated.

At1,6 years a new TSH of 7.98 was measured with FT4 of 1.24. He remains untreated until now and comes to consultation with a TSH of 5.43 T4 11.04 and a TRH/TSH test of 9.77/ 61/51.Ft4 1.13

He has a peculiar face. with some genetic stigmata ( hypertelorism. and strabismus . Ophthalmologic evaluation found a bilateral hypoplasia of the optic nerves and impaired vision. His MRI is normal. He grew in Percentile 10 of height and weight and 3 of Head circumference.

Do you consider that this boy suffers of subclinical hypothyroidism? Should he receive treatment?

Thank you again.

Ana Chiesa, MD

Response

In response to your query, I would certainly be concerned about the possibility of hypopituitarism in your patient, given the history of optic nerve hypoplasia. For this reason, a slightly elevated TSH on occasion and a brisk TSH response to TRH with a failure to normalize are significant, and are compatible with mild secondary hypothyroidism. I am not aware of any data that this degree of mild hypothyroidism imparts a significant risk of cognitive delay, but my tendency would be to treat the patient with a small dose of L-T4 anyway(maybe even starting with 12.5 mcg) with a goal of normalizing the TSH to the mid-normal range. I would also continue to follow the patient closely with respect to his other pituitary hormones. As you know, deficiencies can often develop with time. Please feel free to contact me directly should you have any further questions.

Rosalind S. Brown, M.D.