I would appreciate your input on the following case: DD, a 9yrs and 7 month old white male, was first referred to me 3 months ago for a goiter. He has ADD and is on Concerta. He takes Claritin prn for allergies. He was recovering from an URTI, for which he had been on Amoxicillin. He denied sx of hypo or hyperthyroidism except for 25 pound weight gain in 3 months. There is no known thyroid disorder in the family. O/E his height and weight were at the 90% for his age. PR 74/min. BP - 102/76.Thyroid was mildly enlarged. No nodules, non tender. DTR 2+. No tremors. Rest of the exam was normal. External genitalia -prepubertal. ? Acne on chest, as diagnosed by dermatology. His initial thyroid function tests (3 months prior to being seen by me), were as follows: TSH - 1.47 (0.7 - 6.4); Total T3 - 2.58 (1.23 - 2.110), Total T4 - 7.3 (5.3 - 11.6). I ordered the following tests: TSH - 0.64 (0.7-6.4), Free T4 - 1.14 ().9-1.6), Free T3 - 4.51 (2.3 - 4.20), T3U - 30.4% (27-37), TPO Ab 18.8 (<35). Normal Dex. Sup.Test, FPG - 100, Normal lipid panel. Thyroid USG - (R) - 4.1x1.2x1.3cms (L) - 4.3x 1.3 x 1.4 cm. 0.4 cm cyst L lobe. Homogenous gland, otherwise. Thyroid Uptake and scan was ordered to r/o a toxic adenoma vs SAT: 24% uptake at 24 hrs. Homogenous tracer distribution, without hot or cold nodules. As he was clinally asymptomatic. I reassured mom that he may ha subclinical hyperthyroidism. He was asked to follow up in three months with TFT. At 3 month follow up; his weight was up by 9 lbs, height increased by 1cm. Goiter noted. His repeat blood work is as follows: TSH: 3.12. Free T4 - 1.03. Free T3: 4.84. What is his diagnosis? Would you suggest any further testing or Rx for this patient? I am not aware of increased T3 with Concerta or ADD. I look forward to your comments and advice.
Radha Reddy Chaparral Medical Group, CA
With the normal TSH I do not think one can diagnose hyperthyroidism. It is not clear why his T3 is consistently slightly elevated. Perhaps he does have Hashimoto's thyroiditis despite the normal Ab test, which can occur in children. I am not aware of a condition with selective excess T4-T3 conversion. However with this situation watchful waiting seems in order.
Leslie J De Groot, MD