Inconsistent T4

[marquette94]

My 2 1/2 yr old son, who had congential CMV exposure, was sent for thyroid blood testing to rule out thyroid disorders as contributing to his developmental delays.  He is currently 33mo chronologically, but only 15-18 months developmentally.  His initial results were T4 1.4 (range 4.7-13.3) and TSH of <0.01 (range 0.34-4.82.  I met with the pediatric endocrinologist and we discuss the possibiities, including secondary hypothyroidism and the causes.  A subsequent lab test for T4, TSH, Growth hormone, and antibodies were all within normal ranges.  GH was 96.  One week prior to the first blood tests, he had prednisone, but I am told that should not have affected the T4 and TSH levels.

My son does have rough dry skin, difficulty speaking (could be CMV related though), drinks constantly but has limited interest in food.  He is 75% percentile for growth, which is consisent with his father and my heights.  He will nap for 4-5 hours most days and then still go down for 12 hour night sleep.  His physical therapist notes his energy levels flucuate considerably.  He did not have any other gross illness at the time of the first blood test - he was only having tubes placed in his ears, but there was no infection in the liquid behind.

I am concerned that we may have "caught" something as it is evolving.  My question is, please advise as to any transient pituitary or hypothalmus conditions or if this could be the beginning of a pituitary tumor that has not completely limited the gland's ability to function normally as yet.

[Mark Lupo, M.D.]

The key here will be following the pattern -- would test T4, T3 and TSH every 6-8 weeks to make sure this is stable as I agree the initial testing was concerning for secondary hypothyroidism.  Steroids and acute illness can also cause low TSH & T4 but usually the TSH is not as low as you report in these cases (at least in adults).